Acoustic signal output device

Abstract

To provide an acoustic signal output device that can suppress a sound leakage to the circumference and does not seal up the external auditory canal.SOLUTION: There is provided an acoustic signal output device that has at least two driver units, and the acoustic signal output device has a first driver unit which emits a first acoustic signal to one side and emits a second acoustic signal to the other side, a second driver unit which emits a fourth acoustic signal to the one side and emits a third acoustic signal to the other side, and an enclosure part provided with a sound hole for leading the acoustic signal emitted from the driver unit to the one side toward outside, and a sound hole for leading the acoustic signal emitted from the driver unit to the other side toward outside.SELECTED DRAWING: Figure 27

Description

Technical Field

[0001] The present invention relates to an acoustic signal output device, and particularly to an acoustic signal output device that does not seal the external auditory canal.

Background Art

[0002] In recent years, an increased burden on the ears due to wearing earphones or headphones has become a problem. As a device for reducing the burden on the ears, open-ear (open-type) earphones and headphones that do not block the external auditory canal are known.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, open-ear earphones and headphones have a problem of significant sound leakage to the surroundings. Such a problem is not limited to open-ear earphones and headphones, but is a common problem for acoustic signal output devices that do not seal the external auditory canal.

[0005] The present invention has been made in view of such points, and an object thereof is to provide an acoustic signal output device that does not seal the external auditory canal and can suppress sound leakage to the surroundings.

Means for Solving the Problems

[0006] An acoustic signal output device having at least two driver units is provided. This acoustic signal output device includes a first driver unit that emits a first acoustic signal to one side and a second acoustic signal to the other side, a second driver unit that emits a fourth acoustic signal to one side and a third acoustic signal to the other side, a sound hole that guides the acoustic signal emitted from the driver unit to one side to the outside, and a sound hole that guides the acoustic signal emitted from the driver unit to the other side to the outside, and a housing portion provided with them. However, the frequency bandwidths of the third acoustic signal and the fourth acoustic signal emitted from the second driver unit are narrower than the frequency bandwidths of the first acoustic signal and the second acoustic signal emitted from the first driver unit. The second acoustic signal is a signal having a substantially opposite phase to the first acoustic signal, and the fourth acoustic signal is a signal having a substantially opposite phase to the third acoustic signal.

Effect of the Invention

[0007] With this structure, sound leakage to the surroundings can be suppressed.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [First Embodiment] First, the first embodiment of the present invention will be described. [Configuration] The acoustic signal output device 10 of the present embodiment is a device for acoustic listening (for example, an open-ear type (open type) earphone, headphones, etc.) that is worn without sealing the user's external auditory canal. As illustrated in FIGS. 1, 2A to 2C, and 3A to 3C, the acoustic signal output device 10 of the present embodiment includes a driver unit 11 that converts an output signal (an electrical signal representing an acoustic signal) output from a playback device into an acoustic signal and outputs it, and a housing 12 that houses the driver unit 11 therein.

[0010] [Driver Unit 11] The driver unit (speaker driver unit) 11 is a device (a device with a speaker function) that emits an acoustic signal AC1 (first acoustic signal) based on an input output signal to one side (D1 direction side), and emits an acoustic signal AC2 (second acoustic signal) that is an inverted phase signal (phase inversion signal) of the acoustic signal AC1 or an approximate signal of the inverted phase signal to the other side (D2 direction side). That is, the acoustic signal emitted from the driver unit 11 to one side (D1 direction side) is called the acoustic signal AC1 (first acoustic signal), and the acoustic signal emitted from the driver unit 11 to the other side (D2 direction side) is called the acoustic signal AC2 (second acoustic signal). For example, the driver unit 11 includes a diaphragm 113 that emits the acoustic signal AC1 to the D1 direction side from one surface 113a by vibration, and emits the acoustic signal AC2 to the D2 direction side from the other surface 113b by this vibration (Fig. 2B). In the driver unit 11 of this example, the diaphragm 113 vibrates based on the input output signal, so that the acoustic signal AC1 is emitted from one surface 111 to the D1 direction side, and the acoustic signal AC2, which is an inverted phase signal of the acoustic signal AC1 or an approximate signal of the inverted phase signal, is emitted from the other surface 112 to the D2 direction side. That is, the acoustic signal AC2 is emitted secondarily along with the emission of the acoustic signal AC1. Note that the D2 direction (the other side) is, for example, the reverse direction of the D1 direction (one side), but the D2 direction does not necessarily have to be exactly the reverse direction of the D1 direction, and it is sufficient that the D2 direction is different from the D1 direction. The relationship between the one side (D1 direction) and the other side (D2 direction) depends on the type and shape of the driver unit 11. Also, depending on the type and shape of the driver unit 11, the acoustic signal AC2 may exactly be the inverted phase signal of the acoustic signal AC1, or the acoustic signal AC2 may be an approximate signal of the inverted phase signal of the acoustic signal AC1. For example, the approximate signal of the inverted phase signal of the acoustic signal AC1 may be (1) a signal obtained by shifting the phase of the inverted phase signal of the acoustic signal AC1, (2) a signal obtained by changing (amplifying or attenuating) the amplitude of the inverted phase signal of the acoustic signal AC1, or (3) a signal obtained by shifting the phase of the inverted phase signal of the acoustic signal AC1 and further changing the amplitude.It is desirable that the phase difference between the inverted phase signal of the acoustic signal AC1 and its approximate signal is δ1% or less of one cycle of the inverted phase signal of the acoustic signal AC1. Examples of δ1% are 1%, 3%, 5%, 10%, 20%, etc. Also, it is desirable that the difference between the amplitude of the inverted phase signal of the acoustic signal AC1 and the amplitude of its approximate signal is δ2% or less of the amplitude of the inverted phase signal of the acoustic signal AC1. Examples of δ2% are 1%, 3%, 5%, 10%, 20%, etc. Note that examples of the type of the driver unit 11 include a dynamic type, a balanced armature type, a hybrid type of dynamic type and balanced armature type, a condenser type, etc. Also, there is no limitation on the shape of the driver unit 11 or the diaphragm 113. In the present embodiment, for simplicity of explanation, an example is shown in which the outer shape of the driver unit 11 is a substantially cylindrical shape having both end faces, and the diaphragm 113 is a substantially disc shape, but this does not limit the present invention. For example, the outer shape of the driver unit 11 may be a rectangular parallelepiped shape or the like, or the diaphragm 113 may be a dome shape or the like. Also, examples of the acoustic signal are sounds such as music, voice, sound effects, environmental sounds, etc.

[0011] <Housing 12> The housing 12 is a hollow member having a wall portion on the outside, and houses the driver unit 11 inside. For example, the driver unit 11 is fixed to the end on the D1 direction side inside the housing 12. However, this does not limit the present invention. Although there is no limitation on the shape of the housing 12, for example, it is desirable that the shape of the housing 12 is rotationally symmetric (line symmetric) or substantially rotationally symmetric about the axis A1 extending along the D1 direction. Thereby, it becomes easy to provide sound holes 123a (details will be described later) so that the variation in the energy of the sound emitted from the housing 12 in each direction becomes small. As a result, it becomes easy to reduce sound leakage uniformly in each direction. For example, the housing 12 includes a first end face which is a wall portion 121 disposed on one side (D1 direction side) of the driver unit 11, a second end face which is a wall portion 122 disposed on the other side (D2 direction side) of the driver unit 11, and a space sandwiched between the first end face and the second end face, and a side face which is a wall portion 123 surrounding the space about the axis A1 passing through the first end face and the second end face (FIG. 2B, FIG. 3B). In the present embodiment, for simplicity of explanation, an example in which the housing 12 has a substantially cylindrical shape with both end faces is shown. For example, the distance between the wall portion 121 and the wall portion 122 is 10 mm, and the wall portions 121 and 122 are circular with a radius of 10 mm. However, these are just examples and do not limit the present invention. For example, the housing 12 may have a substantially dome-shaped shape having a wall portion at the end, a substantially cubic shape which is hollow, or other three-dimensional shapes. Also, there is no limitation on the material constituting the housing 12. The housing 12 may be constituted by a rigid body such as synthetic resin or metal, or may be constituted by an elastic body such as rubber.

[0012] <Sound holes 121a, 123a> On the wall of the housing 12, there are provided a sound hole 121a (first sound hole) for guiding the acoustic signal AC1 (first acoustic signal) emitted from the driver unit 11 to the outside, and a sound hole 123a (second sound hole) for guiding the acoustic signal AC2 (second acoustic signal) emitted from the driver unit 11 to the outside. The sound hole 121a and the sound hole 123a are, for example, through holes penetrating the wall of the housing 12, but this does not limit the present invention. As long as the acoustic signals AC1 and AC2 can be respectively guided to the outside, the sound holes 121a and 123a do not have to be through holes.

[0013] The acoustic signal AC1 emitted from the sound hole 121a reaches the external auditory canal of the user and is listened to by the user. On the other hand, from the sound hole 123a, an acoustic signal AC2 that is an inverse phase signal of the acoustic signal AC1 or an approximate signal of the inverse phase signal is emitted. A part of this acoustic signal AC2 cancels out a part (sound leakage component) of the acoustic signal AC1 emitted from the sound hole 121a. That is, by emitting the acoustic signal AC1 (first acoustic signal) from the sound hole 121a (first sound hole) and the acoustic signal AC2 (second acoustic signal) from the sound hole 123a (second sound hole), the attenuation rate η of the acoustic signal AC1 (first acoustic signal) at the position P2 (second location) with respect to the position P1 (first location) 11 can be made a predetermined value η th as follows, or the attenuation amount η of the acoustic signal AC1 (first acoustic signal) at the position P2 (second location) with respect to the position P1 (first location) 12 can be made a predetermined value ω th or more. Here, the position P1 (first location) is a predetermined location where the acoustic signal AC1 (first acoustic signal) emitted from the sound hole 121a (first sound hole) arrives. On the other hand, the position P2 (second location) is a predetermined location whose distance from the acoustic signal output device 10 is farther than the position P1 (first location). The predetermined value η th is a value (lower value) smaller than the attenuation rate η 21 of an arbitrary or specific acoustic signal (sound) by air propagation at the position P2 (second location) with respect to the position P1 (first location). Also, the predetermined value ω this the attenuation amount η of an arbitrary or specific acoustic signal (sound) due to air propagation at position P2 (second location) with respect to position P1 (first location). 22 is a value greater than that. That is, the acoustic signal output device 10 of the present embodiment has an attenuation rate η 11 that is less than a predetermined value η 21 or is designed so that the attenuation amount η th is less than or equal to the following, or the attenuation amount η 12 is designed to be greater than or equal to a predetermined value ω 22 that is greater than the attenuation amount η th . Note that the acoustic signal AC1 is air-propagated from position P1 to position P2 and attenuates due to this air propagation and the acoustic signal AC2. The attenuation rate η 11 is the ratio (AMP2(AC1) / AMP1(AC1)) of the magnitude AMP2(AC1) of the acoustic signal AC1 at position P2, which has attenuated due to air propagation and the acoustic signal AC2, to the magnitude AMP1(AC1) of the acoustic signal AC1 at position P1. Also, the attenuation amount η 12 is the difference (|AMP1(AC1) - AMP2(AC1)|) between the magnitude AMP1(AC1) and the magnitude AMP2(AC1). On the other hand, when the acoustic signal AC2 is not assumed, an arbitrary or specific acoustic signal AC ar propagated through the air from position P1 to position P2 attenuates due to air propagation without being caused by the acoustic signal AC2. The attenuation rate η 21 is the ratio (AMP2(AC ar )) / AMP1(AC ar ) of the magnitude AMP2(AC ar ) of the acoustic signal AC at position P2, which has attenuated due to air propagation (attenuated without being caused by the acoustic signal AC2), to the magnitude AMP1(AC ar ) of the acoustic signal AC at position P1. Also, the attenuation amount η ar is the difference (|AMP1(AC ar ) - AMP2(AC 22 )) between the magnitude AMP1(AC ar ) and the magnitude AMP2(AC ar ). ar ar ​)|). Examples of the magnitude of the acoustic signal include the sound pressure of the acoustic signal or the energy of the acoustic signal. The "sound leakage component" means, for example, a component of the acoustic signal AC1 emitted from the sound hole 121a that is likely to reach an area other than the user wearing the acoustic signal output device 10 (for example, a human other than the user wearing the acoustic signal output device 10). For example, the "sound leakage component" means a component of the acoustic signal AC1 that propagates in a direction other than the D1 direction. For example, mainly the direct wave of the acoustic signal AC1 is emitted from the sound hole 121a, and mainly the direct wave of the second acoustic signal is emitted from the second sound hole. A part of the direct wave (sound leakage component) of the acoustic signal AC1 emitted from the sound hole 121a is canceled by interfering with at least a part of the direct wave of the acoustic signal AC2 emitted from the sound hole 123a. However, this does not limit the present invention, and this cancellation can also occur with waves other than the direct wave. That is, the sound leakage component, which is at least one of the direct wave and the reflected wave of the acoustic signal AC1 emitted from the sound hole 121a, may be canceled by at least one of the direct wave and the reflected wave of the acoustic signal AC2 emitted from the sound hole 123a. Thereby, sound leakage can be suppressed.

[0014] Illustrate the arrangement configuration of the sound holes 121a and 123a. The sound hole 121a (first sound hole) of the present embodiment is provided in the region AR1 (first region) of the wall portion 121 disposed on one side of the driver unit 11 (the D1 direction side which is the side where the acoustic signal AC1 is emitted) (FIGS. 1, 2A, 2B, 3B). That is, the sound hole 121a opens facing the D1 direction (first direction) along the axis A1. Further, the sound hole 123a (second sound hole) of the present embodiment is provided in the region AR3 of the wall portion 123 in contact with the region AR between the region AR1 (first region) of the wall portion 121 of the housing 12 and the region AR2 (second region) of the wall portion 122 disposed on the D2 direction side of the driver unit 11 (the other side where the acoustic signal AC2 is emitted). That is, when the direction between the D1 direction (first direction) and the direction opposite to the D1 direction with respect to the center of the housing 12 is defined as the D12 direction (second direction) (FIG. 3B), the sound hole 121a (first sound hole) is provided on the D1 direction side (first direction side) of the housing 12, and the sound hole 123a (second sound hole) is provided on the D12 direction side (second direction side) of the housing 12. For example, when the housing 12 has a first end face which is the wall portion 121 disposed on one side (D1 direction side) of the driver unit 11, a second end face which is the wall portion 122 disposed on the other side (D2 direction side) of the driver unit 11, and a side face which is the wall portion 123 surrounding the space sandwiched between the first end face and the second end face with the axis A1 along the emission direction (D1 direction) of the acoustic signal AC1 passing through the first end face and the second end face (FIGS. 2B, 3B), the sound hole 121a (first sound hole) is provided on the first end face, and the sound hole 123a (second sound hole) is provided on the side face. Further, in the present embodiment, no sound hole is provided on the wall portion 122 side of the housing 12. This is because if a sound hole is provided on the wall portion 122 side of the housing 12, the sound pressure level of the acoustic signal AC2 emitted from the housing 12 will exceed the level necessary to cancel the sound leakage component of the acoustic signal AC1, and the excess will be perceived as sound leakage.

[0015] As illustrated in FIG. 2A and the like, the sound hole 121a of the present embodiment is disposed on or near the axis A1 along the emission direction (D1 direction) of the acoustic signal AC1. The axis A1 of the present embodiment passes through the center or near the center of the region AR1 (first region) of the wall portion 121 disposed on one side (D1 direction side) of the driver unit 11 of the housing 12. For example, the axis A1 is an axis extending in the D1 direction through the central region of the housing 12. That is, the sound hole 121a of the present embodiment is provided at the central position of the region AR1 of the wall portion 121 of the housing 12. In the present embodiment, for simplicity of explanation, an example is shown in which the shape of the edge of the open end of the sound hole 121a is a circle (the open end is circular). The radius of such a sound hole 121a is, for example, 3.5 mm. However, this does not limit the present invention. For example, the shape of the edge of the open end of the sound hole 121a may be other shapes such as an ellipse, a quadrilateral, or a triangle. Also, the open end of the sound hole 121a may be mesh-shaped. In other words, the open end of the sound hole 121a may be composed of a plurality of holes. Also in the present embodiment, for simplicity of explanation, an example is shown in which one sound hole 121a is provided in the region AR1 (first region) of the wall portion 121 of the housing 12. However, this does not limit the present invention. For example, two or more sound holes 121a may be provided in the region AR1 (first region) of the wall portion 121 of the housing 12.

[0016] The sound hole 123a (second sound hole) of the present embodiment is preferably arranged, for example, in consideration of the following viewpoints. (1) Viewpoint of position: The sound hole 123a is arranged so that the propagation path of the acoustic signal AC2 emitted from the sound hole 123a overlaps the propagation path of the sound leakage component of the acoustic signal AC1 to be canceled. (2) From the perspective of area: Depending on the opening area of the sound hole 123a, the propagation region of the acoustic signal AC2 emitted from the sound hole 123a and the frequency characteristics of the housing 12 are different. Also, the frequency characteristics of the housing 12 affect the frequency characteristics of the acoustic signal AC2 emitted from the sound hole 123a, that is, the amplitude at each frequency. Considering such propagation region and frequency characteristics of the acoustic signal AC2 emitted from the sound hole 123a, in the region where an attempt is made to cancel the sound leakage component, the opening area of the sound hole 123a is determined so that the sound leakage component is canceled by the acoustic signal AC2 emitted from the sound hole 123a. From the above viewpoints, for example, it is desirable that the sound hole 123a (the second sound hole) be configured as follows. For example, as illustrated in FIGS. 2B, 3A, and 3C, it is desirable that a plurality of the sound holes 123a (the second sound holes) of the present embodiment be provided along a circumference (circle) C1 centered on an axis A1 along the emission direction of the acoustic signal AC1 (the first acoustic signal). When a plurality of sound holes 123a are provided along the circumference C1, the acoustic signal AC2 is emitted radially (radially centered on the axis A1) from the sound holes 123a to the outside. Here, the sound leakage component of the acoustic signal AC1 is also emitted radially (radially centered on the axis A1) from the sound hole 121a to the outside. Therefore, by providing a plurality of sound holes 123a along the circumference C1, the sound leakage component of the acoustic signal AC1 can be appropriately canceled by the acoustic signal AC2. In the present embodiment, for simplicity of explanation, an example in which a plurality of sound holes 123a are provided on the circumference C1 is shown. However, it is sufficient that the plurality of sound holes 123a are provided along the circumference C1, and not necessarily all the sound holes 123a need to be exactly arranged on the circumference C1.

[0017] Preferably, when the circumference C1 is equally divided into a plurality of unit arc regions, the total opening area of the sound holes 123a (second sound holes) provided along any one of the unit arc regions, i.e., the first arc region, is the same as or substantially the same as the total opening area of the sound holes 123a (second sound holes) provided along any one of the unit arc regions excluding the first arc region, i.e., the second arc region. For example, as illustrated in FIG. 4, when the circumference C1 is equally divided into four unit arc regions C1-1, …, C1-4, the total opening area of the sound holes 123a (second sound holes) provided along any one of the unit arc regions C1-1, …, C1-4, i.e., the first arc region (for example, the unit arc region C1-1), is the same as or substantially the same as the total opening area of the sound holes 123a (second sound holes) provided along any one of the unit arc regions excluding the first arc region, i.e., the second arc region (for example, the unit arc region C1-2). Here, for the sake of simplicity of explanation, an example in which the circumference C1 is equally divided into four unit arc regions C1-1, …, C1-4 is shown, but this does not limit the present invention. Also, “α1 and α2 are substantially the same” means that the difference between α1 and α2 is β% or less of α1. Examples of β% are 3%, 5%, 10%, etc. Thereby, the sound pressure distribution of the acoustic signal AC2 emitted from the sound holes 123a provided along the first arc region and the sound pressure distribution of the acoustic signal AC2 emitted from the sound holes 123a provided along the second arc region are point-symmetrical or substantially point-symmetrical with respect to the axis A1. Preferably, the total opening area of the sound holes 123a (second sound holes) provided along each unit arc region is the same as or substantially the same for each unit arc region. Thereby, the sound pressure distribution of the acoustic signal AC2 emitted from the sound holes 123a is point-symmetrical or substantially point-symmetrical with respect to the axis A1. Thereby, the sound leakage component of the acoustic signal AC1 can be more appropriately canceled out by the acoustic signal AC2.

[0018] More preferably, it is desirable that the plurality of sound holes 123a are provided along the circumference C1 with the same shape, the same size, and the same interval. For example, a plurality of sound holes 123a having a width of 4 mm and a height of 3.5 mm are provided along the circumference C1 with the same shape, the same size, and the same interval. When the plurality of sound holes 123a are provided along the circumference C1 with the same shape, the same size, and the same interval, the sound leakage component of the acoustic signal AC1 can be more appropriately canceled by the acoustic signal AC2. However, this does not limit the present invention.

[0019] Also preferably, the sound hole 123a (second sound hole) is provided in a wall portion in contact with a region AR located on the other side (D2 direction side) of the driver unit 11 (FIG. 3B). Thereby, the direct wave of the acoustic signal AC2 emitted from the other side of the driver unit 11 is efficiently led out from the sound hole 123a to the outside. As a result, the sound leakage component of the acoustic signal AC1 can be more appropriately canceled by the acoustic signal AC2.

[0020] In the present embodiment, for the sake of simplicity of explanation, the case where the shape of the edge portion of the open end of the sound hole 123a is a quadrangle (when the open end is a square) is illustrated, but this does not limit the present invention. For example, the shape of the edge portion of the open end of the sound hole 123a may be other shapes such as a circle, an ellipse, a triangle, etc. Also, the open end of the sound hole 123a may be in a mesh shape. In other words, the open end of the sound hole 123a may be constituted by a plurality of holes. Also, the number of the sound holes 123a is not limited, and a single sound hole 123a may be provided in the region AR3 of the wall portion 123 of the housing 12, or a plurality of sound holes 123a may be provided.

[0021] It is desirable that the ratio S2 / S1 of the total opening area S2 of the sound holes 123a (second sound holes) to the total opening area S1 of the sound holes 121a (first sound holes) satisfies 2 / 3 ≤ S2 / S1 ≤ 4 (details will be described later). Thereby, the sound leakage component of the acoustic signal AC1 can be appropriately canceled by the acoustic signal AC2.

[0022] The sound leakage suppression performance may also depend on the ratio between the area of the wall portion 123 where the sound hole 123a is provided and the opening area of the sound hole 123a. For example, assume that the housing 12 has a first end face which is a wall portion 121 arranged on one side (D1 direction side) of the driver unit 11, a second end face which is a wall portion 122 arranged on the other side (D2 direction side) of the driver unit 11, and a side face which is a wall portion 123 surrounding a space sandwiched between the first end face and the second end face with an axis A1 along the emission direction (D1 direction) of the acoustic signal AC1 passing through the first end face and the second end face. Assume that a sound hole 121a (first sound hole) is provided on the first end face and a sound hole 123a (second sound hole) is provided on the side face (FIG. 2B, FIG. 3B). In such a case, it is desirable that the ratio S2 / S3 of the total sum S2 of the opening areas of the sound holes 123a to the total area S3 of the side face is 1 / 20 ≦ S2 / S3 ≦ 1 / 5 (details will be described later). Thereby, the sound leakage component of the acoustic signal AC1 can be appropriately canceled by the acoustic signal AC2. However, this does not limit the present invention.

[0023] <Operating state> Using FIG. 5A, the operating state of the acoustic signal output device 10 is illustrated. In the example of FIG. 5A, one acoustic signal output device 10 is mounted on each of the right ear 1010 and the left ear 1020 of the user 1000. An arbitrary mounting mechanism is used for mounting the acoustic signal output device 10 on the ear. The acoustic signal output device 10 has its D1 direction side directed toward the user 1000 side. The output signals output from the playback device 100 are input to the driver units 11 of the respective acoustic signal output devices 10, and the driver units 11 emit an acoustic signal AC1 to the D1 direction side and an acoustic signal AC2 to the other side. The acoustic signal AC1 is emitted from the sound hole 121a, and the emitted acoustic signal AC1 enters the right ear 1010 and the left ear 1020 and is listened to by the user 1000. On the other hand, from the sound hole 123a, an acoustic signal AC2 which is an inverse phase signal of the acoustic signal AC1 or an approximate signal of the inverse phase signal is emitted. A part of this acoustic signal AC2 cancels a part (sound leakage component) of the acoustic signal AC1 emitted from the sound hole 121a.

[0024] <Experimental results> Experimental results showing the sound leakage suppression effect by the acoustic signal output device 10 of this embodiment are presented. In this experiment, as shown in FIG. 5B, the acoustic signal output device 10 was attached to both ears of a dummy head 1100 simulating a human head, and the acoustic signals were observed at positions P1 and P2. Position P1 in this example is a position near the left ear 1120 of the dummy head 1100 (near the acoustic signal output device 10), and position P2 is a position 15 cm away from position P1 outward.

[0025] FIG. 6 illustrates the frequency characteristics of the acoustic signal observed at position P1 in FIG. 5B, FIG. 7 illustrates the frequency characteristics of the acoustic signal observed at position P2 in FIG. 5B, and FIG. 8 illustrates the difference (the difference in sound pressure level at each frequency) between the frequency characteristics of the acoustic signal observed at position P1 and the frequency characteristics of the acoustic signal observed at position P2. The horizontal axis represents frequency (Frequency [Hz]), and the vertical axis represents sound pressure level (Sound pressure level (SPL) [dB]). The solid-line graph illustrates the frequency characteristics when using the acoustic signal output device 10 of this embodiment, and the dashed-line graph illustrates the frequency characteristics when using a conventional acoustic signal output device (open-ear type earphone). As illustrated in FIG. 8, when using the acoustic signal output device 10 of this embodiment, it can be seen that the difference between the sound pressure of the acoustic signal observed at position P1 and the sound pressure of the acoustic signal observed at position P2 is larger than when using a conventional acoustic signal output device. This indicates that the acoustic signal output device 10 of this embodiment can suppress sound leakage at position P2 compared to the conventional acoustic signal output device.

[0026] FIG. 9A illustrates the relationship between the ratio S2 / S1 of the total opening area S2 of the sound holes 123a (second sound holes) to the total opening area S1 of the sound holes 121a (first sound holes), and the difference between the frequency characteristics of the acoustic signal observed at position P1 and the frequency characteristics of the acoustic signal observed at position P2. The horizontal axis represents the ratio S2 / S1, and the vertical axis represents the sound pressure level (Sound pressure level (SPL) [dB]) representing the difference. r12h6 illustrates the result when the number of the sound holes 121a is 6 and the number of the sound holes 123a is 4, r12h12 illustrates the result when the number of the sound holes 121a is 12 and the number of the sound holes 123a is 4, and r45h35 illustrates the result when the number of the sound holes 121a is 1 and the number of the sound holes 123a is 4. As illustrated in FIG. 9A, in the range of 2 / 3 ≦ S2 / S1 ≦ 4 of the ratio S2 / S1 of the total opening area S2 of the sound holes 123a to the total opening area S1 of the sound holes 121a, particularly, it can be seen that the difference between the sound pressure of the acoustic signal observed at position P1 and the sound pressure of the acoustic signal observed at position P2 is large. This indicates that the sound leakage suppression effect in this range is large. FIG. 9B illustrates the relationship between the ratio S2 / S3 of the total opening area S2 of the sound holes 123a (second sound holes) to the total side area S3, and the difference between the frequency characteristics of the acoustic signal observed at position P1 and the frequency characteristics of the acoustic signal observed at position P2. The horizontal axis represents the ratio S2 / S3, and the vertical axis represents the sound pressure level (Sound pressure level (SPL) [dB]) representing the difference. The meanings of r12h6, r12h12, and r45h35 are the same as those in FIG. 9A. As illustrated in FIG. 9B, in the range of 1 / 20 ≦ S2 / S3 ≦ 1 / 5 of the ratio S2 / S3 of the total opening area S2 of the sound holes 123a to the total side area S3, particularly, it can be seen that the difference between the sound pressure of the acoustic signal observed at position P1 and the sound pressure of the acoustic signal observed at position P2 is large. This indicates that the sound leakage suppression effect in this range is large.

[0027] [Modification Example 1 of the First Embodiment] In the first embodiment, an example was shown in which a plurality of sound holes 123a (second sound holes) having the same shape, the same size, and the same interval are provided along the circumference C1. However, this does not limit the present invention. A plurality of sound holes 123a having different shapes and / or sizes and / or intervals may be provided along the circumference C1. For example, as illustrated in FIGS. 10A, 10B, 11A, 11B, and 12A, a plurality of sound holes 123a having different shapes and intervals may be provided in the wall portion 123 along the circumference C1, or as illustrated in FIG. 12B, a plurality of sound holes 123a having different intervals may be provided in the wall portion 123 along the circumference C1, or as illustrated in FIG. 12C, a plurality of sound holes 123a having different shapes and sizes may be provided in the wall portion 123 along the circumference C1.

[0028] Also, even in such a case, when the circumference C1 is equally divided into a plurality of unit arc regions, the total opening area of the sound holes 123a (second sound holes) provided along a first arc region, which is any one of the unit arc regions, is preferably the same as or substantially the same as the total opening area of the sound holes 123a provided along a second arc region, which is any one of the unit arc regions excluding the first arc region. More preferably, it is desirable that the total opening area of the sound holes 123a provided along each unit arc region is the same as or substantially the same for each unit arc region. For example, as illustrated in FIGS. 10A, 10B, 11A, and 11B, although the number and size of the sound holes 123a provided in each unit arc region C1-1, C1-2, C1-3, C1-4 are different from each other, the total opening area of the sound holes 123a provided in the unit arc region C1-1, the total opening area of the sound holes 123a provided in the unit arc region C1-2, the total opening area of the sound holes 123a provided in the unit arc region C1-3, and the total opening area of the sound holes 123a provided in the unit arc region C1-4 are all preferably the same as or substantially the same as each other.

[0029] It is sufficient that the plurality of sound holes 123a are along the circumference C1, and not all of the sound holes 123a necessarily have to be arranged exactly on the circumference C1. For example, as shown in FIGS. 12A, 12B, and 12C, not all of the sound holes 123a have to be arranged on the circumference C1, and it is sufficient that these plurality of sound holes 123a are arranged along the circumference C1. Note that the position of the circumference C1 is not limited to that exemplified in the first embodiment, and any circumference centered on the axis A1 may be used.

[0030] Furthermore, if a sufficient sound leakage suppression effect can be obtained, not all of the sound holes 123a have to be arranged along the circumference C1. That is, some of the sound holes 123a may be arranged at positions deviated from the circumference C1. Also, if a sufficient sound leakage suppression effect can be obtained, there is no limitation on the number of the sound holes 123a, and only one sound hole 123a may be provided.

[0031] [Modification Example 2 of the First Embodiment] In the first embodiment, a configuration is exemplified in which one sound hole 121a is disposed at the central position (hereinafter simply referred to as the "central position") of the region AR1 (the region of the wall portion on one side of the driver unit) of the wall portion 121 of the housing 12. However, a plurality of sound holes 121a may be provided in the region AR1 of the wall portion 121 of the housing 12, or the sound hole 121a may be offset to an eccentric position deviated from the center (central position) of the region AR1 of the wall portion 121 of the housing 12. For example, as illustrated in FIG. 13A, one sound hole 121a may be provided at an eccentric position (a position on an axis A12 parallel to the axis A1 deviated from the axis A1) on the region AR1 (hereinafter simply referred to as the "eccentric position"). In other words, the position of one sound hole 121a provided in the region AR1 may be offset to the eccentric position. Alternatively, as illustrated in FIG. 13B, a plurality of sound holes 121a may be provided in the region AR1, and these plurality of sound holes 121a may be offset to an eccentric position on an axis A12 parallel to the axis A1 deviated from the axis A1. In other words, the positions of the plurality of sound holes 121a provided in the region AR1 may be offset to the eccentric position. That is, the sound hole 121a may be provided singly or in plurality, and the sound hole 121a may be offset to the central position of the region AR1 of the wall portion 121 of the housing 12 or to the eccentric position. Note that there is no limitation on the distance between the axis A1 and the axis A12, and it may be set according to the required sound leakage suppression performance. An example of the distance between the axis A1 and the axis A12 is 4 mm, but this does not limit the present invention.

[0032] The resonance frequency of the housing 12 can be controlled by the arrangement configuration of the sound holes 121a provided in the area AR1 (for example, the number, size, interval, arrangement, etc. of the sound holes 121a). The resonance frequency of the housing 12 affects the frequency characteristics of the acoustic signals emitted from the sound holes 121a and 123a. Therefore, the frequency characteristics of the acoustic signals emitted from the sound holes 121a and 123a can be controlled by the arrangement configuration of the sound holes 121a provided in the area AR1. For example, when the frequencies of the acoustic signals AC1 and AC2 increase, their wavelengths become shorter, and it becomes difficult to phase-match the sound leakage components of the acoustic signal AC1 emitted to the outside so that they are canceled by the acoustic signal AC2. As a result, the higher the frequencies of the acoustic signals AC1 and AC2, the more difficult it becomes to suppress the sound leakage of the acoustic signal AC1. At the resonance frequency of the housing 12, since the sound pressure levels of the acoustic signals AC1 and AC2 increase, if the resonance frequency of the housing 12 belongs to a high frequency band where it is difficult to suppress sound leakage, the sound leakage will be perceived significantly. To solve this problem, the arrangement configuration of the sound holes 121a may be set as in the following Examples 2-1 and 2 to control the resonance frequency of the housing 12.

[0033] <Example 2-1> In a high frequency band where it is difficult to suppress sound leakage, the arrangement configuration of the sound holes 121a may be set so that the human auditory sensitivity to the resonance frequency of the housing 12 becomes low. For example, at a predetermined frequency f of the housing 12 where the position of the sound hole 121a is offset to a certain eccentric position th Let the human auditory sensitivity (ease of hearing) to the acoustic signal of the above resonance frequency be S d And at a predetermined frequency f of the housing 12 where the sound hole 121a is provided at the central position th Let the human auditory sensitivity to the acoustic signal of the resonance frequency above be S c Let the auditory sensitivity S in this case d be lower than the auditory sensitivity S c That is, at a predetermined frequency f of the housing 12 where the position of the sound hole 121a (the first sound hole) is offset to a certain eccentric position (a position deviated from the center of the area of the wall portion arranged on one side of the driver unit), the human auditory sensitivity S to the acoustic signal of the resonance frequency above th d The resonance frequency of the housing 12 can be controlled by the arrangement configuration of the sound holes 121a provided in the area AR1 (for example, the number, size, interval, arrangement, etc. of the sound holes 121a). The resonance frequency of the housing 12 affects the frequency characteristics of the acoustic signals emitted from the sound holes 121a and 123a. Therefore, the frequency characteristics of the acoustic signals emitted from the sound holes 121a and 123a can be controlled by the arrangement configuration of the sound holes 121a provided in the area AR1. For example, when the frequencies of the acoustic signals AC1 and AC2 increase, their wavelengths become shorter, and it becomes difficult to phase-match the sound leakage components of the acoustic signal AC1 emitted to the outside so that they are canceled by the acoustic signal AC2. As a result, the higher the frequencies of the acoustic signals AC1 and AC2, the more difficult it becomes to suppress the sound leakage of the acoustic signal AC1. At the resonance frequency of the housing 12, since the sound pressure levels of the acoustic signals AC1 and AC2 increase, if the resonance frequency of the housing 12 belongs to a high frequency band where it is difficult to suppress sound leakage, the sound leakage will be perceived significantly. To solve this problem, the arrangement configuration of the sound holes 121a may be set as in the following Examples 2-1 and 2 to control the resonance frequency of the housing 12.

[0033] <Example 2-1> In a high frequency band where it is difficult to suppress sound leakage, the arrangement configuration of the sound holes 121a may be set so that the human auditory sensitivity to the resonance frequency of the housing 12 becomes low. For example, at a predetermined frequency f of the housing 12 where the position of the sound hole 121a is offset to a certain eccentric position th Let the human auditory sensitivity (ease of hearing) to the acoustic signal of the above resonance frequency be S d And at a predetermined frequency f of the housing 12 where the sound hole 121a is provided at the central position th Let the human auditory sensitivity to the acoustic signal of the resonance frequency above be S c Let the auditory sensitivity S in this case d be lower than the auditory sensitivity S c That is, at a predetermined frequency f of the housing 12 where the position of the sound hole 121a (the first sound hole) is offset to a certain eccentric position (a position deviated from the center of the area of the wall portion arranged on one side of the driver unit), the human auditory sensitivity S to the acoustic signal of the resonance frequency above th dis the predetermined frequency f of the housing 12 when it is assumed that the sound hole 121a is provided at the central position (the center of the region of the wall portion disposed on one side of the driver unit). th The human auditory sensitivity S to the acoustic signal of the above resonance frequency c is lower. The position of the sound hole 121a may be offset to such an eccentric position. Note that the auditory sensitivity may be any index representing the ease of hearing sound. The higher the auditory sensitivity, the easier it is to hear. An example of auditory sensitivity is the reciprocal of the sound pressure level of the sound necessary for a human to perceive a sound of a reference magnitude. For example, the reciprocal of the sound pressure level at each frequency in the equal-loudness curve is the auditory sensitivity. The predetermined frequency f th means the lower limit of the frequency band including the frequency at which it becomes difficult to cancel out the sound leakage component of the acoustic signal AC1 with the acoustic signal AC2. The predetermined frequency f th Examples of are 3000 Hz, 4000 Hz, 5000 Hz, 6000 Hz, etc.

[0034] <Example 2-2> Depending on the arrangement configuration of the sound hole 121a, the resonance peak of the magnitude of the acoustic signal AC1 and / or the acoustic signal AC2 emitted from the housing 12 may be blurred. For example, the magnitude of the acoustic signal AC1 emitted from the sound hole 121a of the housing 12 and / or the acoustic signal AC2 emitted from the sound hole 123a, where the position of the sound hole 121a is offset to a certain eccentric position, at a predetermined frequency f th Let the sharpness (acuteness) of the peak above be Q d Also, let the sharpness of the peak of the magnitude of the acoustic signal AC1 emitted from the sound hole 121a of the housing 12 and / or the acoustic signal AC2 emitted from the sound hole 123a at a predetermined frequency f th above be Q c Let it be. The sharpness Q of the peak in this case d is assumed to be duller than the sharpness Q of the peak c That is, the acoustic signal AC1 (first acoustic signal) emitted from the sound hole 121a (first sound hole) of the housing 12 and / or the acoustic signal AC2 (second acoustic signal) emitted from the sound hole 123a (second sound hole), where the position of the sound hole 121a (first sound hole) is offset to a certain eccentric position, at a predetermined frequency fth Peak sharpness Q above d is the magnitude of the acoustic signal AC1 (first acoustic signal) emitted from the sound hole 121a (first sound hole) of the housing 12 and / or the acoustic signal AC2 (second acoustic signal) emitted from the sound hole 123a (second sound hole) at a predetermined frequency f, assuming that the sound hole 121a is provided at the central position th Peak sharpness Q above c is less sharp. In other words, the magnitude of the acoustic signal AC1 and / or the acoustic signal AC2 emitted from the housing 12 with the position of the sound hole 121a offset to a certain eccentric position at a predetermined frequency f th The peak above is flattened compared to the peak of the magnitude of the acoustic signal AC1 and / or the acoustic signal AC2 emitted from the housing 12 assuming that the sound hole 121a is provided at the central position at a predetermined frequency f th above. The position of the sound hole 121a may be offset to such an eccentric position

[0035] When the positions of the single or plural sound holes 121a are offset to an eccentric position, the distribution and the opening area of the sound holes 123a may be offset accordingly. For example, as shown in FIG. 13A or FIG. 13B, the positions of the single or plural sound holes 121a provided in the region AR1 are offset to an eccentric position on an axis A12 shifted from the axis A1, and as illustrated in FIGS. 14A and 14B, the opening area of the sound holes 123a provided in the region AR3 may also be offset to the eccentric position side on the axis A12. In the example of FIG. 14A, the number of the sound holes 123a provided along a unit arc region C1-3 far from the eccentric position on the axis A12 is smaller than the number of the sound holes 123a provided along a unit arc region C1-1 closer to the eccentric position than the unit arc region C1-3. The example of FIG. 14B is that each opening area of the sound holes 123a provided along a unit arc region C1-3 far from the eccentric position on the axis A12 is smaller than each opening area of the sound holes 123a provided along a unit arc region C1-1 closer to the eccentric position than the unit arc region C1-3. That is, when the circumference C1 is equally divided into a plurality of unit arc regions, the total sum of the opening areas of the sound holes 123a (second sound holes) provided along any one of the unit arc regions, for example, a first arc region (e.g., C1-3), is smaller than the total sum of the opening areas of the sound holes 123a provided along a second arc region (e.g., C1-1), which is any one of the unit arc regions closer to the eccentric position than the first arc region. When the positions of the sound holes 121a are offset to an eccentric position, the distribution of the acoustic signal AC1 emitted from the sound holes 121a is also offset to the eccentric position. Here, by also offsetting the distribution and the opening area of the sound holes 123a to the eccentric position, the distribution of the acoustic signal AC2 emitted from the sound holes 123a can also be offset to the eccentric position. Thereby, the sound leakage component of the acoustic signal AC1 can be sufficiently canceled out by the emitted acoustic signal AC2.

[0036] In order to control the resonance frequency of the housing 12 for other purposes, the sound hole 121a may be displaced to an eccentric position shifted from the center (central position) of the region AR1 of the wall portion 121 of the housing 12. Also, the sizes of the openings of the sound holes 121a and 123a, the thickness of the wall portion of the housing 12, and the volume inside the housing 12 affect the resonance frequency of the housing 12. Therefore, by controlling at least a part of these, the resonance frequency of the housing 12 can be increased or decreased. That is, the larger the sizes of the openings of the sound holes 121a and 123a, the thinner the thickness of the wall portion of the housing 12, and the smaller the volume inside the housing 12, the higher the resonance frequency of the housing 12 can be. Conversely, the smaller the sizes of the openings of the sound holes 121a and 123a, the thicker the thickness of the wall portion of the housing 12, and the larger the volume inside the housing 12, the lower the resonance frequency of the housing 12 can be.

[0037] [Modification Example 3 of the First Embodiment] As described above, in the first embodiment and its modification examples 1 and 2, the sound hole 123a emits an acoustic signal AC2 that is an inverted phase signal of the acoustic signal AC1 or an approximate signal of the inverted phase signal, and a part of the emitted acoustic signal AC2 cancels out a part (sound leakage component) of the acoustic signal AC1 emitted from the sound hole 121a. For this purpose, when the direct wave of the acoustic signal AC1 is mainly emitted from the sound hole 121a, it is desirable that the direct wave of the acoustic signal AC2 is mainly emitted from the sound hole 123a. Since the reflection wave has a different propagation path from the direct wave, when the acoustic signal AC2 emitted from the sound hole 123a contains a reflection wave, the acoustic signal AC2 emitted from the sound hole 123a may exhibit a different phase from the inverted phase signal of the acoustic signal AC1 emitted from the sound hole 121a or an approximate signal of the inverted phase signal, and the efficiency of canceling out the sound leakage component may decrease. That is, it is desirable that the housing 12 has an internal structure that suppresses the reverberation of the acoustic signal AC2 (second acoustic signal) inside the housing 12, and the direct wave of the acoustic signal AC2 is mainly emitted from the sound hole 123a (second sound hole). Hereinafter, such a configuration will be exemplified.

[0038] [Example 3-1] An anti-resonance material (e.g., sponge, paper, etc.) for suppressing resonance may be installed in the internal region (e.g., regions AR2, AR3) of the wall portion of the housing 12. The wall portion of the housing 12 itself may be composed of an anti-resonance material, or a sheet-like anti-resonance material may be fixed to the wall portion of the housing 12. Alternatively, the shape of the internal region (e.g., regions AR2, AR3) of the wall portion of the housing 12 may be made into a concavo-convex shape to suppress resonance. Alternatively, a sheet with a concavo-convex surface shape having an anti-resonance effect may be fixed to the internal region of the wall portion of the housing 12.

[0039] <Example 3-2> As illustrated in FIGS. 15A and 15B, the opening end of the sound hole 123a (second sound hole) may be directed toward the edge portion 112a on the other side 112 (D2 direction side) of the driver unit 11, and a direct wave of the acoustic signal AC2 (second acoustic signal) mainly emitted from the other side 112 of the driver unit 11 may be emitted from the sound hole 123a.

[0040] <Example 3-3> As illustrated in FIG. 15B, the wall portion 122 (region AR2) disposed on the other side of the driver unit 11 is non-contact with the driver unit 11 (non-contact during the driving of the driver unit 11), and the distance dis1 between the driver unit 11 and the wall portion 122 disposed on the other side 112 of the driver unit 11 is 5 mm or less, and a direct wave of the acoustic signal AC2 (second acoustic signal) may be mainly emitted from the sound hole 123a (second sound hole). Note that the fact that the region AR2 is non-contact with the driver unit 11 during the driving of the driver unit 11 means, for example, that the distance dis1 is larger than the amplitude of the other side 112 of the driver unit 11 during driving.

[0041] [Modification Example 4 of the First Embodiment] As described above, as the frequencies of the acoustic signals AC1 and AC2 increase, their wavelengths become shorter, and it becomes difficult to cancel out the sound leakage component of the acoustic signal AC1 with the acoustic signal AC2. In some cases, it becomes difficult to phase-align the acoustic signals AC1 and AC2 at high frequencies, and conversely, it is conceivable that the sound leakage component of the acoustic signal AC1 may be amplified by the acoustic signal AC2. Therefore, it may be better to suppress the emission of the high-frequency acoustic signal AC2 from the sound hole 123a. For this purpose, a sound-absorbing material for absorbing high-frequency acoustic signals may be provided in the housing 12. This sound-absorbing material has the property that the sound absorption rate for the acoustic signal with frequency f1 is greater than the sound absorption rate for the acoustic signal with frequency f2. However, the frequency f1 is higher than the frequency f2 (f1 > f2). That is, this sound-absorbing material suppresses the high-frequency component of the acoustic signal more than the low-frequency component. The frequency f1 is a predetermined frequency f2 th as follows, and the frequency f2 is the predetermined frequency f2 th which is greater. Examples of the predetermined frequency f2 th are 3000 Hz, 4000 Hz, 5000 Hz, 6000 Hz, etc. Note that the sound absorption rate α of the sound-absorbing material is expressed by α = (E in - E out ) / E in when the energy of the acoustic signal input to the sound-absorbing material is E out and the energy of the acoustic signal reflected by the sound-absorbing material or the energy of the acoustic signal passing through the sound-absorbing material is E in . Examples of such sound-absorbing materials include papers such as Japanese paper and half-size paper, non-woven fabrics, silk, cotton, etc.

[0042] <Example 4-1> The sound-absorbing material 13 may be provided in at least any one of the sound holes 123a (second sound holes). For example, as illustrated in FIG. 16A, the sound-absorbing material 13 may be packed in at least any one of the sound holes 123a. At least one of the inside or outside of at least any one of the sound holes 123a may be covered with the sound-absorbing material 13.

[0043] <Example 4-2> The sound-absorbing material 13 may be provided in the area on the other side 112 (the D2 direction side) of the driver unit 11 inside the housing 12. For example, as illustrated in FIG. 16B, the sound-absorbing material 13 may be fixed to the area AR2 of the wall portion 122 arranged on the other side 112 (the D2 direction side) of the driver unit 11. The sound-absorbing material 13 may be fixed inside the wall portion 123.

[0044] <Example 4-3> The sound-absorbing material 13 may be provided in at least any one of the sound holes 123a (the second sound holes), and the sound-absorbing material 13 may be provided in the area on the other side 112 (the D2 direction side) of the driver unit 11 inside the housing 12. For example, as illustrated in FIG. 16C, the sound-absorbing material 13 may be packed in at least any one of the sound holes 123a, and further, the sound-absorbing material 13 may be fixed to the area AR2 of the wall portion 122.

[0045] <Experimental results> Experimental results showing the sound leakage suppression effect of the acoustic signal output device 10 of this modified example are shown. In this experiment, an experiment was conducted between the case of using the acoustic signal output device 10 of the first embodiment (no acoustic absorbent: No acoustic absorbent) and the case of using the acoustic signal output device 10 in which the sound hole 123a was covered with an acoustic absorbent as illustrated in this modified example (with acoustic absorbent: With acoustic absorbent). Japanese paper was used as the acoustic absorbent. Also in this experiment, as shown in FIG. 5B, the acoustic signal output device 10 was attached to both ears of the dummy head 1100 simulating a human head, and the acoustic signal was observed at positions P1 and P2. The position P1 is a position near the left ear 1120 of the dummy head 1100 (near the acoustic signal output device 10), and the position P2 is a position 15 cm away from the position P1 outward.

[0046] FIG. 17 illustrates the frequency characteristics of the acoustic signal observed at position P1 in FIG. 5B, FIG. 18 illustrates the frequency characteristics of the acoustic signal observed at position P2 in FIG. 5B, and FIG. 19 illustrates the difference between the frequency characteristics of the acoustic signal observed at position P1 and the frequency characteristics of the acoustic signal observed at position P2. The horizontal axis represents frequency (Frequency [Hz]), and the vertical axis represents sound pressure level (Sound pressure level (SPL) [dB]). The solid line graph illustrates the frequency characteristics when the acoustic signal output device 10 with the sound hole 123a covered with an acoustic absorbent (With acoustic absorbent) is used, and the dashed line graph illustrates the frequency characteristics when the acoustic signal output device 10 of the first embodiment is used (No acoustic absorbent). As illustrated in FIG. 19, in the frequency band of 2000 Hz or more, generally, when the acoustic signal output device 10 with the sound hole 123a covered with an acoustic absorbent is used, the difference between the sound pressure of the acoustic signal observed at position P1 and the sound pressure of the acoustic signal observed at position P2 is larger than when the acoustic signal output device 10 without an acoustic absorbent is used. This indicates that in the frequency band of 2000 Hz or more, generally, when the acoustic signal output device 10 with the sound hole 123a covered with an acoustic absorbent is used, sound leakage at position P2 can be suppressed.

[0047] [Second Embodiment] Next, a second embodiment of the present invention will be described. The second embodiment is a modification of the first embodiment. Hereinafter, the description will focus on the differences from the matters described so far, and the matters already described will be simplified by using the same reference numerals.

[0048] In order to improve the sound quality of the acoustic signal output device 10 of the first embodiment or its modification, it may be necessary to increase the size of the driver unit 11. However, in the first embodiment or its modification, when the size of the driver unit 11 increases, the size and weight of the acoustic signal output device 10 itself also increase. However, wearing an acoustic signal output device 10 with a large size and weight near the external auditory canal increases the burden on the ear and the feeling of foreign objects. Therefore, the housing provided with the sound hole and the driver unit 11 may be separate bodies, and these may be connected by a waveguide. Thereby, it becomes possible to increase the size of the driver unit 11 without increasing the size and weight of the housing mounted near the external auditory canal. This will be described in detail below.

[0049] The acoustic signal output device 20 of the present embodiment is also a device for acoustic listening that is worn without sealing the user's external auditory canal. As illustrated in FIG. 20, the acoustic signal output device 20 of the present embodiment includes a driver unit 11, a housing 22 having hollow portions AR21, AR22 (first and second hollow portions), a housing 23 that houses the driver unit 11 therein, hollow waveguides 24, 25 (first and second waveguides) that connect the housing 22 and the housing 23, and hollow joint members 26, 27 that connect the waveguides 24, 25 to the housing 22.

[0050] <Driver unit 11> As illustrated in FIG. 20, the driver unit 11 is a device that emits an acoustic signal AC1 (first acoustic signal) based on an input output signal to one side (D3 direction side) and emits an acoustic signal AC2 (second acoustic signal), which is an inverted phase signal of the acoustic signal AC1 or an approximate signal of the inverted phase signal, to the other side (D4 direction side). The configuration of the driver unit 11 is the same as that of the first embodiment except that the D1 direction is replaced with the D3 direction and the D2 direction is replaced with the D4 direction.

[0051] <Housing 23> As illustrated in FIG. 20, the housing 23 is a hollow member having a wall portion on the outside, and houses the driver unit 11 inside. Although there is no limitation on the shape of the housing 23, for example, it is desirable that the shape of the housing 23 is rotationally symmetric (line symmetric) or substantially rotationally symmetric about an axis A2 extending along the D3 direction. In the present embodiment, for simplicity of explanation, an example in which the housing 23 has a substantially cylindrical shape with both end faces is shown. However, this is merely an example and does not limit the present invention. For example, the housing 23 may have a substantially dome-shaped configuration having a wall portion at the end, a substantially cubic shape that is hollow, or any other three-dimensional shape. One end 241 of the waveguide 24 is attached to the wall portion 231 of the housing 23 disposed on the surface 111 side on one side (D3 direction side) of the driver unit 11. The waveguide 24 (first waveguide) having one end 241 connected to one side (D3 direction side) of the driver unit 11 in this way guides the acoustic signal AC1 emitted from the surface 111 of the driver unit 11 to the outside of the housing 23. One end 251 of the waveguide 25 is attached to the wall portion 232 of the housing 23 disposed on the surface 112 side on the other side (D4 direction side) of the driver unit 11. The waveguide 25 (second waveguide) having one end 251 connected to the other side (D4 direction side) of the driver unit 11 in this way guides the acoustic signal AC2 emitted from the surface 112 of the driver unit 11 to the outside of the housing 23. Note that there is no limitation on the material constituting the housing 23. The housing 23 may be constituted by a rigid body such as synthetic resin or metal, or may be constituted by an elastic body such as rubber.

[0052] <Waveguides 24 and 25> As illustrated in FIG. 20, the waveguides 24 and 25 are, for example, hollow members configured in a tubular shape, and each transmits the acoustic signals AC1 and AC2 input from one ends 241 and 251 to the other ends 242 and 252, and emits them from the other ends 242 and 252. However, the waveguides 24 and 25 are not limited to the tubular shape, and any structure that guides the acoustic signal picked up at one ends 241 and 251 (the first positions) to the other ends 242 and 252 (the second positions) different from the one ends 241 and 251 (the first positions) may be used. There is no limitation on the lengths of the waveguides 24 and 25, but preferably, the length of the sound path of the waveguide 24 is equal to the length of the sound path of the waveguide 25, or the difference between the length of the sound path of the waveguide 24 and the length of the sound path of the waveguide 25 is an integral multiple of the wavelength of the acoustic signals AC1 and AC2. That is, when the length of the sound path of the waveguide 24 (the first waveguide) is L1, the length of the sound path of the waveguide 25 (the second waveguide) is L2, n is an integer, and the acoustic signal AC1 (the first acoustic signal) and the acoustic signal AC2 (the second acoustic signal) include acoustic signals with a wavelength λ, it is desirable to satisfy L1 = L2 + nλ. Note that the sound path is the path of sound, and in the case of the waveguides 24 and 25 having the same inner diameter, a specific example of the length of the sound path of the waveguides 24 and 25 is the length of the waveguides 24 and 25. Note that there is no limitation on the material constituting the waveguides 24 and 25. The waveguides 24 and 25 may be constituted by a rigid body such as synthetic resin or metal, or may be constituted by an elastic body such as rubber.

[0053] <Joint member 26> The joint member 26 is a hollow member having an open end 261 located on one side, a wall portion 262 which is a bottom surface located on the other side of the open end 261, and a wall portion 263 which is a side surface surrounding the space between the open end 261 and the wall portion 262 with the axis A1 as the center. The axis A1 of the present embodiment passes through the open end 261 and the wall portion 262. Preferably, the axis A1 is perpendicular or substantially perpendicular to the wall portion 262. Also preferably, the joint member 26 is rotationally symmetric with respect to the axis A1. In the present embodiment, for the sake of simplicity of explanation, an example in which the wall portion 263 has a cylindrical shape is shown, but the wall portion 263 may have other shapes such as a prismatic shape. The other end 242 of the waveguide 24 is attached to the wall portion 263, and the acoustic signal AC1 emitted from the other end 242 of the waveguide 24 is introduced into the interior of the joint member 26 (the space between the open end 261 and the wall portion 262). The acoustic signal AC1 introduced into the interior of the joint member 26 is emitted from the open end 261. Note that there is no limitation on the material constituting the joint member 26. The joint member 26 may be constituted by a rigid body such as a synthetic resin or metal, or may be constituted by an elastic body such as rubber.

[0054] <Joint member 27> Similarly, the joining member 27 is a hollow member having an open end 271 located on one side, a wall portion 272 which is a bottom surface located on the other side of the open end 271, and a wall portion 273 which is a side surface surrounding the space between the open end 271 and the wall portion 272 with the axis A1 as the center. The axis A1 of the present embodiment passes through the open end 271 and the wall portion 272. Preferably, the axis A1 is perpendicular or substantially perpendicular to the wall portion 272. Also preferably, the joining member 27 is rotationally symmetric with respect to the axis A1. In the present embodiment, for simplicity of explanation, an example in which the wall portion 273 has a cylindrical shape is shown, but the wall portion 273 may have other shapes such as a prismatic shape. The other end 252 of the waveguide 25 is attached to the wall portion 273, and the acoustic signal AC2 emitted from the other end 252 of the waveguide 25 is introduced into the interior of the joining member 27 (the space between the open end 271 and the wall portion 272). The acoustic signal AC2 introduced into the interior of the joining member 27 is emitted from the open end 271. There is no limitation on the material constituting the joining member 27. The joining member 27 may be constituted by a rigid body such as a synthetic resin or metal, or may be constituted by an elastic body such as rubber.

[0055] <Housing 22> As illustrated in FIGS. 20, 21A - 21C, 22A, and 22B, the housing 22 of the present embodiment has a wall portion 221 located on one side (the D1 direction side), a wall portion 222 located on the other side (the D2 direction side), a wall portion 223 surrounding the space between the wall portion 221 and the wall portion 222, and a wall portion 224 separating the space surrounded by the wall portion 221, the wall portion 222, and the wall portion 223 into a hollow portion AR21 (first hollow portion) and a hollow portion AR22 (second hollow portion). In the present embodiment, the hollow portion AR21 and the hollow portion AR22 are arranged on the axis A1 extending in the same D1 direction. For example, the central regions of the hollow portion AR21 and the hollow portion AR22 are arranged on the same axis A1. It is desirable that the internal space of the hollow portion AR21 is separated from the internal space of the hollow portion AR22 by the wall portion 224.

[0056] On the inner wall of the hollow portion AR21, a joint member 26 to which the other end 242 of the waveguide 24 is attached is fixed or integrated, and the open end 261 side of the joint member 26 is directed toward the wall portion 221 side. For example, the wall portion 262 side of the joint member 26 is fixed or integrated with the inner wall portion 224 of the hollow portion AR21, and the open end 261 side is directed toward the wall portion 221 side. In the example of the present embodiment, the centers of the wall portion 262 and the open end 261 of the joint member 26 are arranged on the axis A1. Thereby, the other end 242 of the waveguide 24 is connected to the hollow portion AR21 via the joint member 26, and the acoustic signal AC1 sent to the joint member 26 is emitted from the open end 261 toward the wall portion 221 side (D1 direction side). That is, for example, the joint member 26 is arranged on the axis A1, the open end 261 of the joint member 26 is open facing the direction D1 (first direction) along the axis A1, and the acoustic signal AC1 introduced from the other end 242 of the waveguide 24 is emitted toward the direction D1 inside the hollow portion AR21.

[0057] A through-hole 222a is provided in the wall portion 222 of the hollow portion AR22. The through-hole 222a is preferably arranged on the axis A1, and more preferably, the center of the through-hole 222a is arranged on the axis A1. Further, although there is no limitation on the shape of the through-hole 222a, it is preferably that the opening portion of the through-hole 222a is rotationally symmetric with respect to the axis A1, and more preferably, the edge of the opening portion of the through-hole 222a is a circle. On the outside of the wall portion 222 of the housing 22, a joining member 27 to which the other end 252 of the waveguide 25 is attached is fixed or integrated, and the open end 271 side of the joining member 27 is directed toward the through-hole 222a. In the example of the present embodiment, the wall portion 272, the open end 271 of the joining member 27, and the center of the through-hole 222a are arranged on the axis A1. Thereby, the other end 252 of the waveguide 25 is connected to the hollow portion AR22 via the joining member 27, and the acoustic signal AC2 sent to the joining member 27 is emitted from the open end 271 toward the internal space of the hollow portion AR22. For example, the acoustic signal AC2 is emitted from the open end 271 toward the wall portion 224 side (D1 direction side). That is, for example, the joining member 27 is arranged on the axis A1, the open end 271 of the joining member 27 opens facing the direction D1 (first direction) along the axis A1, and the acoustic signal AC2 introduced from the other end 252 of the waveguide 25 is emitted toward the direction D1 inside the hollow portion AR22.

[0058] Although there is no limitation on the shape of the housing 22, for example, it is desirable that the shape of the housing 22 is rotationally symmetric or substantially rotationally symmetric about the axis A1. In the present embodiment, for simplicity of explanation, an example is shown in which the outer shape of the housing 22 has a substantially cylindrical shape with wall portions 221 and 222 that are both end faces and a wall portion 223 that is a side face. Further, in the present embodiment, an example is shown in which the wall portions 221, 222, and 224 are perpendicular or substantially perpendicular to the axis A1, and the wall portion 223 is parallel or substantially parallel to the axis A1. However, these are merely examples and do not limit the present invention. For example, the outer shape of the housing 22 may be a substantially dome shape having wall portions at the ends, a substantially hollow cubic shape, or other three-dimensional shapes. Also, there is no limitation on the material that constitutes the housing 22. The housing 22 may be constituted by a rigid body such as synthetic resin or metal, or may be constituted by an elastic body such as rubber.

[0059] <Sound holes 221a, 223a> In the wall portion 221 of the hollow portion AR21 (first hollow portion), a sound hole 221a (first sound hole) is provided for guiding the acoustic signal AC1 (first acoustic signal) introduced into the hollow portion AR21 by the waveguide 24 (first waveguide) to the outside. Further, in the wall portion 223 of the hollow portion AR22 (second hollow portion), a sound hole 223a (second sound hole) is provided for guiding the acoustic signal AC2 (second acoustic signal) introduced into the hollow portion AR22 by the waveguide 25 (second waveguide) to the outside. Similar to the sound holes 121a and 123a of the first embodiment, the sound holes 221a and 223a are, for example, through holes penetrating the wall portion of the housing 12, but this does not limit the present invention. As long as the acoustic signals AC1 and AC2 can be respectively guided to the outside, the sound holes 221a and 223a do not have to be through holes.

[0060] The acoustic signal AC1 emitted from the sound hole 221a reaches the user's external auditory canal and is listened to by the user. On the other hand, from the sound hole 223a, an acoustic signal AC2 that is an inverted phase signal of the acoustic signal AC1 or an approximate signal of the inverted phase signal is emitted. A part of this acoustic signal AC2 cancels out a part (sound leakage component) of the acoustic signal AC1 emitted from the sound hole 221a. Thereby, sound leakage can be suppressed.

[0061] The arrangement configurations of sound holes 221a and 223a are illustrated. The sound hole 221a (first sound hole) of the present embodiment is provided in the wall portion 221 of the hollow portion AR21 disposed on one side of the joining member 26 (the D1 direction side which is the side where the acoustic signal AC1 is emitted) (FIGS. 20, 21A, 21B, 22A). Further, the sound hole 223a (second sound hole) of the present embodiment is provided in the wall portion 223 in contact with the hollow portion AR22. That is, assuming that the direction between the D1 direction (first direction) and the direction opposite to the D1 direction with respect to the center of the hollow portion AR22 is the D12 direction (second direction) (FIG. 22A), the sound hole 221a (first sound hole) is provided on the D1 direction side (first direction side) of the housing 22, and the sound hole 223a (second sound hole) is provided on the D12 direction side (second direction side) of the housing 22. That is, the sound hole 221a opens facing the D1 direction (first direction) along the axis A1, and the sound hole 223a opens facing the D12 direction (second direction). For example, when the outer shape of the housing 22 includes a first end face which is the wall portion 221 disposed on one side (D1 direction side) of the joining member 26, a second end face which is the wall portion 222 disposed on the other side (D2 direction side) of the joining member 26, and a side face which is the wall portion 223 surrounding the space sandwiched between the first end face and the second end face about the axis A1 along the emission direction (D1 direction) of the acoustic signal AC1 passing through the first end face and the second end face (FIGS. 21B, 22A), the sound hole 221a (first sound hole) is provided in the first end face, and the sound hole 223a (second sound hole) is provided in the side face. Also, in the present embodiment, no sound hole is provided on the wall portion 222 side of the housing 22. This is because if a sound hole is provided on the wall portion 222 side of the housing 22, the sound pressure level of the acoustic signal AC2 emitted from the housing 22 exceeds the level necessary to cancel the sound leakage component of the acoustic signal AC1, and the excess is perceived as sound leakage.

[0062] As illustrated in FIG. 21A etc., the sound hole 221a of the present embodiment is arranged on or near the axis A1 along the emission direction (D1 direction) of the acoustic signal AC1. The axis A1 of the present embodiment passes through the center or near the center of the region of the wall portion 221 arranged on one side (D1 direction side) of the joining member 26. For example, the axis A1 is an axis extending in the D1 direction through the central region of the housing 22. That is, the sound hole 221a of the present embodiment is provided at the central position of the region of the wall portion 221 of the housing 22. In the present embodiment, for simplicity of explanation, an example is shown in which the shape of the edge of the open end of the sound hole 221a is a circle (the open end is circular). However, this does not limit the present invention. For example, the shape of the edge of the open end of the sound hole 221a may be other shapes such as an ellipse, a quadrilateral, or a triangle. Also, the open end of the sound hole 221a may be in a mesh shape. In other words, the open end of the sound hole 221a may be composed of a plurality of holes. Also in the present embodiment, for simplicity of explanation, an example is shown in which one sound hole 221a is provided in the wall portion 221 of the housing 22. However, this does not limit the present invention. For example, two or more sound holes 221a may be provided in the wall portion 221 of the housing 22.

[0063] Similar to the first embodiment, as illustrated in FIGS. 21B and 22B, a plurality of sound holes 223a (second sound holes) of the present embodiment are provided along a circumference C1 centered on the axis A1 along the emission direction of the acoustic signal AC1 (first acoustic signal). In the present embodiment, for simplicity of explanation, an example is shown in which a plurality of sound holes 223a are provided on the circumference C1. However, it is sufficient that the plurality of sound holes 223a are provided along the circumference C1, and not all of the sound holes 223a necessarily have to be arranged exactly on the circumference C1.

[0064] Also similar to the first embodiment, preferably, when the circumference C1 is equally divided into a plurality of unit arc regions, the total opening area of the sound holes 223a (second sound holes) provided along any one of the unit arc regions, which is the first arc region, is the same as or substantially the same as the total opening area of the sound holes 223a (second sound holes) provided along any one of the unit arc regions excluding the first arc region, which is the second arc region (FIG. 22B).

[0065] Similar to the first embodiment, more preferably, the plurality of sound holes 223a are desirably provided along the circumference C1 with the same shape, the same size, and the same interval. However, this does not limit the present invention.

[0066] In the present embodiment, for the sake of simplicity of explanation, a case where the shape of the edge of the open end of the sound hole 223a is a quadrangle is exemplified, but this does not limit the present invention. For example, the shape of the edge of the open end of the sound hole 223a may be other shapes such as a circle, an ellipse, a triangle, etc. Also, the open end of the sound hole 223a may be in a mesh shape. In other words, the open end of the sound hole 223a may be constituted by a plurality of holes. Also, there is no limitation on the number of the sound holes 223a, and a single sound hole 223a may be provided in the wall portion 223 of the housing 22, or a plurality of sound holes 223a may be provided.

[0067] Similar to the first embodiment, it is desirable that the ratio S2 / S1 of the total opening area S2 of the sound holes 223a (second sound holes) to the total opening area S1 of the sound holes 221a (first sound holes) satisfies 2 / 3 ≦ S2 / S1 ≦ 4. Also, when the outer shape of the housing 22 has a first end face which is the wall portion 221 disposed on one side (D1 direction side) of the joining member 26, a second end face which is the wall portion 222 disposed on the other side (D2 direction side) of the joining member 26, and a side face which is the wall portion 223 surrounding the space sandwiched between the first end face and the second end face with an axis A1 along the emission direction (D1 direction) of the acoustic signal AC1 passing through the first end face and the second end face (FIGS. 21B and 22A), it is desirable that the ratio S2 / S3 of the total opening area S2 of the sound holes 223a to the total area S3 of the side face is 1 / 20 ≦ S2 / S3 ≦ 1 / 5.

[0068] <Usage state> Using FIGS. 23A and 23B, the usage state of the acoustic signal output device 20 is illustrated. In the example of FIG. 23A, one acoustic signal output device 20 is mounted on each of the right ear 1010 of the user 1000 and the left ear (not shown). Any mounting mechanism can be used to mount the acoustic signal output device 20 on the ear. The housing 22 of the acoustic signal output device 20 is disposed on the right ear 1010 and on the side of the external auditory canal 1011 of the left ear, with the D1 direction side facing the external auditory canal 1011 side of the user 1000 respectively. Also, the playback device 210 including the housing 23 is disposed on the back side of the auricles of the right ear 1010 and the left ear respectively, and as described above, the housing 23 and the housing 22 are connected by the waveguide tubes 24, 25. The acoustic signal AC1 introduced from the driver unit 11 in the housing 23 into the hollow portion AR21 of the housing 22 is emitted from the sound hole 221a, and the emitted acoustic signal AC1 is listened to by the user 1000. On the other hand, the acoustic signal AC2 introduced from the driver unit 11 in the housing 23 into the hollow portion AR22 of the housing 22 is emitted from the sound hole 223a. A part of this acoustic signal AC2 is an inverted phase signal of the acoustic signal AC1 or an approximate signal of the inverted phase signal, and cancels a part (sound leakage component) of the acoustic signal AC1 emitted from the sound hole 221a.

[0069] As in the example of FIG. 23B, the playback device 210 including the housing 23 may be disposed on the head on the front side of the auricles of the right ear 1010 and the left ear, and as described above, the housing 23 and the housing 22 may be connected by the waveguide tubes 24, 25. Otherwise, it is the same as the example of FIG. 23A.

[0070] [Modification Example 1 of the Second Embodiment] In the second embodiment, an example is shown in which a plurality of sound holes 223a (second sound holes) having the same shape, the same size, and the same interval are provided along the circumference C1. However, this does not limit the present invention. For example, sound holes 223a having the same arrangement configuration as the arrangement configuration of the sound holes 123a in Modification Example 1 of the first embodiment may be provided in the housing 22 (FIGS. 10A to 12C).

[0071] [Modification Example 2 of the Second Embodiment] In the second embodiment, a configuration in which one sound hole 221a is arranged at the center position of the wall portion 221 of the housing 22 was exemplified. However, similar to the second modification of the first embodiment, a plurality of sound holes 221a may be provided in the region of the wall portion 221 of the housing 22, or the sound hole 221a may be offset to an eccentric position deviated from the center of the region of the wall portion 221 of the housing 22. For example, the sound hole 221a having the same arrangement configuration as the arrangement configuration of the sound hole 121a in the second modification of the first embodiment may be provided in the housing 22 (FIGS. 13A and 13B).

[0072] Also, similar to the second modification of the first embodiment, when the positions of the single or plurality of sound holes 221a are offset to an eccentric position, the distribution and the opening area of the sound hole 223a may be offset accordingly. That is, when the circumference C1 is equally divided into a plurality of unit arc regions, the sum of the opening areas of the sound holes 223a (second sound holes) provided along a first arc region, which is one of the unit arc regions, may be smaller than the sum of the opening areas of the sound holes 223a provided along a second arc region, which is one of the unit arc regions closer to the eccentric position than the first arc region. For example, the sound hole 223a having the same arrangement configuration as the arrangement configuration of the sound hole 123a in the second modification of the first embodiment may be provided in the housing 22 (FIGS. 14A and 14B). In addition, the resonance frequency of the housing 22 may be controlled by controlling at least a part of the size of the openings of the sound holes 221a and 223a, the thickness of the wall portion of the housing 22, and the volume inside the housing 22.

[0073] [Modification 3 of the Second Embodiment] In the acoustic signal output device 20, an acoustic absorption material with a greater acoustic absorption rate for an acoustic signal with a frequency f1, as described in Modification Example 4 of the First Embodiment, than for an acoustic signal with a frequency f2 (f1 > f2) may be provided. The acoustic absorption material may be provided on the other side 112 (D4 direction side) of the driver unit 11 inside the housing 23, may be provided inside the waveguide 25 (second waveguide), may be provided at the end (open end portion) of the waveguide 25, may be provided in at least any one of the sound holes 223a (second sound holes), or may be provided inside the hollow portion AR22 (second hollow portion). For example, in Examples 4-1 to 4-3 of Modification Example 4 of the First Embodiment, a configuration may be adopted in which the housing 12 is replaced with the hollow portion AR22, the sound hole 123a is replaced with the sound hole 223a, the region on the other side 112 of the driver unit 11 is replaced with the internal region of the hollow portion AR22, and the region AR2 of the wall portion 122 is replaced with the region of the wall portion 222.

[0074] [Modification Example 4 of the Second Embodiment] By providing the joining members 26 and 27 as in the second embodiment, the emission directions of the acoustic signals AC1 and AC2 in the hollow portions AR21 and AR22 can be controlled. For example, the acoustic signal AC1 introduced from the other end 242 of the waveguide 24 can be emitted in the direction D1 along the axis A1 inside the hollow portion AR21, and the acoustic signal AC2 introduced from the other end 252 of the waveguide 25 can also be emitted in the direction D1 inside the hollow portion AR22. In this case, the sound pressure distributions of the acoustic signal AC1 emitted from the sound hole 221a and the acoustic signal AC2 emitted from the sound hole 223a can be made rotationally symmetric or substantially rotationally symmetric with respect to the axis A1. Thereby, it becomes possible to appropriately suppress sound leakage. However, this does not limit the present invention. For example, as illustrated in FIGS. 24, 25A, 25B, 25C, and 26, the acoustic signal output device 20 does not have the joining member 26, and the other end 242 side of the waveguide 24 is directly connected to the wall portion 223 of the hollow portion AR21, and the acoustic signal AC1 sent to the other end 242 of the waveguide 24 may be emitted toward the inside of the hollow portion AR21. Similarly, the acoustic signal output device 20 does not have the joining member 27, and the other end 252 side of the waveguide 25 is directly connected to the wall portion 223 of the hollow portion AR22, and the acoustic signal AC2 sent to the other end 252 of the waveguide 25 may be emitted toward the inside of the hollow portion AR22.

[0075] Also, in the second embodiment, an example is shown in which the internal space of the hollow portion AR21 of the housing 22 is separated from the internal space of the hollow portion AR22 by the wall portion 224 (FIGS. 20, 21B, 22A). However, the internal space of the hollow portion AR21 of the housing 22 does not necessarily have to be separated from the internal space of the hollow portion AR22. In such a case, it is preferable that the open end 261 of the joining member 26 is directed toward the wall portion 221 side (D1 direction side) of the housing 22 (for example, the sound hole 221a side), and the open end 271 of the joining member 27 is directed toward the wall portion 222 side (D2 direction side) of the housing 22. Even with such a configuration, the acoustic signal AC1 is emitted from the sound hole 221a, and the acoustic signal AC2 is emitted from the sound hole 223a.

[0076] [Third Embodiment] A plurality of the acoustic signal output devices 10 described in the first embodiment or its modified example may be provided and independently controlled. Thereby, the sound pressure level of the acoustic signal AC1 emitted from a certain acoustic signal output device 10 and the sound pressure level of the acoustic signal AC2 emitted from another acoustic signal output device 10 can be independently controlled. For example, a certain acoustic signal output device 10 and another acoustic signal output device 10 can be driven in opposite phases or substantially opposite phases, and the levels (powers) at their respective frequencies can be independently controlled. Thereby, as exemplified in the first embodiment, the sound leakage component of the acoustic signal AC1 of each individual acoustic signal output device 10 is canceled by a part of the acoustic signal AC2, and a part of the acoustic signal AC1 and a part of the acoustic signal AC2 output from different acoustic signal output devices 10 can be canceled out. As a result, it becomes possible to more appropriately cancel the sound leakage component. In the present embodiment, for simplicity of explanation, an example is shown in which two acoustic signal output devices 10 are provided for one ear and are independently controlled. However, this does not limit the present invention, and three or more acoustic signal output devices 10 may be provided for one ear and independently controlled. Regarding the matters already described, the description is omitted using the same reference numerals, but branch numbers are used to distinguish members having the same configuration that exist in plurality. For example, two existing acoustic signal output devices 10 are denoted as the acoustic signal output device 10-1 and the acoustic signal output device 10-2, but the configuration of the acoustic signal output devices 10-1, 2 is the same as that of the acoustic signal output device 10.

[0077] The acoustic signal output device 30 of the present embodiment is a device for acoustic listening that is worn without sealing the user's external auditory canal. As exemplified in FIGS. 27 and 28, the acoustic signal output device 30 of the present embodiment includes the acoustic signal output devices 10-1, 2, a circuit unit 31, and a connection unit 32.

[0078] <Acoustic signal output device 10-1> The configuration of the acoustic signal output device 10-1 is the same as that of the acoustic signal output device 10 illustrated in the first embodiment and its modified example. That is, the acoustic signal output device 10-1 includes a driver unit 11-1 (first driver unit) and a housing 12-1 (first housing portion) that houses the driver unit 11-1 therein. Based on the input output signal I (an electrical signal representing an acoustic signal), the driver unit 11-1 emits an acoustic signal AC1-1 (first acoustic signal) toward the D1-1 direction side (one side), and emits an acoustic signal AC2-1 (second acoustic signal), which is an inverted phase signal of the acoustic signal AC1-1 (first acoustic signal) or an approximate signal of the inverted phase signal, toward the D2-1 direction side (the other side). The wall portion 121-1 of the housing 12-1 is provided with one or more sound holes 121a-1 (first sound holes) for guiding the acoustic signal AC1-1 (first acoustic signal) emitted from the driver unit 11-1 to the outside. The wall portion 123-1 of the housing 12-1 is provided with one or more sound holes 123a-1 (second sound holes) for guiding the acoustic signal AC2-1 (second acoustic signal) emitted from the driver unit 11-1 to the outside. The details of the configuration of the acoustic signal output device 10-1 are the same as those of the acoustic signal output device 10 described in the first embodiment. For example, a plurality of sound holes 123a-1 (second sound holes) are provided along a circumference C1-1 (first circumference) centered on an axis A1-1 (first axis) parallel or substantially parallel to a straight line extending in the direction D1-1 (first direction) (FIG. 29). For example, when the circumference C1-1 (first circumference) is equally divided into a plurality of first unit arc regions, the total opening area of the sound holes 123a-1 (second sound holes) provided along a first arc region, which is any one of the first unit arc regions, is the same as or substantially the same as the total opening area of the sound holes 123a-1 (second sound holes) provided along a second arc region, which is any one of the first unit arc regions excluding the first arc region.

[0079] <Acoustic signal output device 10-2> The configuration of the audio signal output device 10-2 is the same as that of the audio signal output device 10 illustrated in the first embodiment and its modification. That is, the audio signal output device 10-2 includes a driver unit 11-2 (second driver unit) and a housing 12-2 (second housing part) that houses the driver unit 11-2 therein. The driver unit 11-2 emits an audio signal AC1-2 (fourth audio signal) toward the D1-2 direction side (one side) and an audio signal AC2-2 (third audio signal), which is an inverted phase signal or an approximate signal of the inverted phase signal of the audio signal AC1-2, toward the D2-2 direction side (the other side) based on the input output signal II (electrical signal representing an audio signal). The phase of the audio signal AC1-2 (fourth audio signal) is the same as or approximate to the phase of the audio signal AC2-1 (second audio signal). The phase of the audio signal AC2-2 (third audio signal) is the same as or approximate to the phase of the audio signal AC1-1 (first audio signal). Note that the driver unit 11-2 may have the same design as the driver unit 11-1 or a different design from the driver unit 11-1. For example, the driver unit 11-2 may be smaller than the driver unit 11-1, or the performance of the driver unit 11-2 may be inferior to that of the driver unit 11-1. One or a plurality of sound holes 123a-2 (third sound holes) for leading out the audio signal AC2-2 (third audio signal) emitted from the driver unit 11-2 to the outside are provided in the wall portion 123-2 of the housing 12-2. One or a plurality of sound holes 121a-2 (fourth sound holes) for leading out the audio signal AC1-2 (fourth audio signal) emitted from the driver unit 11-2 to the outside are provided in the wall portion 121-2 of the housing 12-2. The details of the configuration of the audio signal output device 10-2 are the same as those of the audio signal output device 10 described in the first embodiment. For example, a plurality of the sound holes 123a-2 (third sound holes) are provided along a circumference C1-2 (fourth circumference) centered on an axis A1-2 (fourth axis) parallel or substantially parallel to a straight line extending in the direction D1-2 (fourth direction) (FIG. 29).For example, when the circumference C1-2 (the fourth circumference) is equally divided into a plurality of fourth unit arc regions, the sum of the opening areas of the sound holes 123a-2 (the third sound holes) provided along any one of the third arc regions, which are any of the fourth unit arc regions, is the same as or substantially the same as the sum of the opening areas of the sound holes 123a-2 (the third sound holes) provided along any one of the fourth arc regions, which are the fourth unit arc regions excluding the third arc region.

[0080] <Connection part 32> As illustrated in FIGS. 27, 28, and 29, the connection part 32 fixes the housing 12-1 of the acoustic signal output device 10-1 and the housing 12-2 of the acoustic signal output device 10-2 to each other. In the example of FIG. 28, the outside of the wall part 123-1 of the housing 12-1 of the acoustic signal output device 10-1 and the outside of the wall part 123-2 of the housing 12-2 of the acoustic signal output device 10-2 are joined. The sound hole 121a-1 (the first sound hole) opens facing the direction D1-1 (the first direction) along the axis A1-1. Note that the direction D1-1 is the direction along the axis A1-1. The sound hole 123a-1 (the second sound hole) opens facing the direction D12-1 (the second direction) between the direction D1-1 (the first direction) and the opposite direction of the direction D1-1 (the first direction). The sound hole 121a-2 (the fourth sound hole) opens facing the direction D1-2 (the fourth direction) that is the same as or approximate to the direction D1-1 (the first direction). Note that the direction D1-2 is the direction along the axis A1-2. The sound hole 123a-2 (the third sound hole) opens facing the D12-2 (the third direction) between the direction D1-2 (the fourth direction) and the opposite direction of the direction D1-2 (the fourth direction). However, this arrangement configuration is an example and does not limit the present invention.

[0081] As illustrated in FIGS. 27, 28, and 29, preferably, the sound hole 121a-1 (first sound hole) and the sound hole 121a-2 (fourth sound hole) are preferably plane-symmetrical or substantially plane-symmetrical with respect to a reference plane P31 including a straight line (axis A1-1) extending in the direction D1-1 (first direction) or a straight line substantially parallel thereto. Similarly, the sound hole 123a-1 (second sound hole) and the sound hole 123a-2 (third sound hole) are preferably plane-symmetrical or substantially plane-symmetrical with respect to the reference plane P31. More preferably, the housing 12-1 (first housing portion) and the housing 12-2 (second housing portion) are plane-symmetrical or substantially plane-symmetrical with respect to the reference plane P31.

[0082] <Circuit section 31> The circuit section 31 is a circuit that uses, as an input, an input signal that is an electrical signal representing an acoustic signal, and outputs an output signal I that is an electrical signal for driving the driver unit 11-1 and an output signal II that is an electrical signal for driving the driver unit 11-2. The output signal I and the output signal II are electrical signals representing acoustic signals, and the output signal II is an inverted phase signal of the output signal I or an approximate signal of the inverted phase signal. The configuration of the circuit section 31 is exemplified below.

[0083] <Configuration example 1 of circuit section 31> The circuit section 31 illustrated in FIG. 30A has a phase inversion section 311 that is a phase inversion circuit. The input signal input to the circuit section 31 is output as the output signal I as it is and supplied to the driver unit 11-1. Further, the input signal input to the circuit section 31 is also input to the phase inversion section 311. The phase inversion section 311 outputs an inverted phase signal of the input signal or an approximate signal of the inverted phase signal as the output signal II. The output signal II is supplied to the driver unit 11-2.

[0084] <Configuration example 2 of circuit section 31> The circuit unit 31 illustrated in FIG. 30B includes a level correction unit 312, a phase control unit 313, and a delay correction unit 314. The input signal input to the circuit unit 31 is input to the level correction unit 312 and the delay correction unit 314. The level correction unit 312 adjusts the level of each frequency band of the input signal and outputs a band level-adjusted signal obtained thereby. That is, if the designs (such as aperture and structure) of the driver units 11-1 and 11-2 are different from each other, the frequency characteristics of the acoustic signals output from the driver units 11-1 and 11-2 are also different. The difference in the frequency characteristics of the acoustic signals output from the driver units 11-1 and 11-2 is related to the cancellation effect of sound leakage. For example, if the housing 12-1 and the housing 12-2 are plane-symmetric with respect to the reference plane P31, it is desirable that the frequency characteristics of the acoustic signals output from the driver units 11-1 and 11-2 be the same in order to enhance the cancellation effect of sound leakage. Therefore, it is desirable to adjust the output signal so that the frequency characteristics of the acoustic signals output from the driver units 11-1 and 11-2 become the same. On the other hand, when the housing 12-1 and the housing 12-2 are not plane-symmetric with respect to the reference plane P31, it is desirable to adjust the balance of the frequency characteristics of the acoustic signals output from the driver units 11-1 and 11-2 so that the cancellation effect of sound leakage becomes higher according to these asymmetries. The level correction unit 312 realizes these by adjusting the level of each band of the input signal. The band level-adjusted signal output from the level correction unit 312 is input to the phase control unit 313. The phase control unit 313 generates an inverse phase signal of the band level-adjusted signal or an approximate signal of the inverse phase signal and outputs this as the output signal II. The phase control unit 313 is, for example, a phase inversion circuit or an all-pass filter. When the phase control unit 313 is an all-pass filter, an inverse phase signal of the band level-adjusted signal or an approximate signal of the inverse phase signal can be generated in consideration of the phase characteristics of the level correction unit 312. The output signal II is supplied to the driver unit 11-2. Also, the delay correction unit 314 outputs an output signal I with the delay amount of the input input signal adjusted. That is, when a delay occurs in the processes (filter processes) of the level correction unit 312 and the phase control unit 313, the delay correction unit 314 adjusts the delay amount.This enables adjustment of the phase of the acoustic signals output from the driver units 11-1 and 11-2, and can improve the sound leakage suppression effect. The output signal I is supplied to the driver unit 11-1. As described above, in Configuration Example 2 of the circuit unit 31, the output signals I and II based on the input signal can be independently controlled.

[0085] <Configuration Example 3 of Circuit Unit 31> As described above, the higher the frequencies of the acoustic signals AC1 and AC2, the shorter their wavelengths, and it becomes difficult to cancel out the sound leakage component of the acoustic signal AC1 with the acoustic signal AC2. For example, in the frequency range exceeding 6000 Hz, this cancellation becomes difficult. Therefore, in such a high frequency band, the acoustic signal AC2 for suppressing the sound leakage component may instead promote sound leakage. On the other hand, in earphones and the like, the level in the low frequency sound range is weak, so the influence of sound leakage is also small. For example, in the frequency range below 2000 Hz, the influence of sound leakage is small. Therefore, in such a low frequency band, the importance of the acoustic signal AC2 for suppressing the sound leakage component is low. Furthermore, the human auditory sensitivity to acoustic signals with frequencies from 2000 Hz to 6000 Hz is relatively high. That is, the importance of the acoustic signal AC2 for suppressing the sound leakage component of the acoustic signal AC1 in such a frequency band is high.

[0086] From the above viewpoints, when allowing the user to listen to the acoustic signal AC1 emitted from the sound hole 121a-1 of the acoustic signal output device 10-1, the frequency band of the acoustic signal emitted from the acoustic signal output device 10-2 may be restricted compared to the frequency band of the acoustic signal emitted from the acoustic signal output device 10-1. That is, the frequency band widths BW-2 of the acoustic signals AC2-2 and AC1-2 (the third and fourth acoustic signals) emitted from the driver unit 11-2 (the second driver unit) may be narrower than the frequency band widths BW-1 of the acoustic signals AC1-1 and AC2-1 (the first and second acoustic signals) emitted from the driver unit 11-1 (the first driver unit).

[0087] Example 31-1: For example, the magnitudes (levels) on the high-frequency side of the acoustic signal AC2-2 and the acoustic signal AC1-2 may be suppressed more than the magnitudes on the high-frequency side of the acoustic signal AC1-1 and the acoustic signal AC2-1. That is, for the acoustic signals AC2-2 and AC1-2 (the third acoustic signal and the fourth acoustic signal) emitted from the driver unit 11-2 (the second driver unit), the magnitude of the component with a frequency f 31 (the first frequency) or higher may be smaller than the magnitude of the component with the same frequency f 31 or higher of the acoustic signals AC1-1 and AC2-1 (the first acoustic signal and the second acoustic signal) emitted from the driver unit 11-1 (the first driver unit). For example, the driver unit 11-2 may output the acoustic signals AC2-2 and AC1-2 in which the frequency band with a frequency f 31 or higher is suppressed. Specific examples of the frequency f 31 are 3000 Hz, 4000 Hz, 5000 Hz, 6000 Hz, etc.

[0088] Example 31-2: For example, the magnitudes on the low-frequency side of the acoustic signal AC2-2 and the acoustic signal AC1-2 may be suppressed more than the magnitudes on the low-frequency side of the acoustic signal AC1-1 and the acoustic signal AC2-1. That is, for the acoustic signals AC2-2 and AC1-2 (the third acoustic signal and the fourth acoustic signal) emitted from the driver unit 11-2 (the second driver unit), the magnitude of the component with a frequency f 32 (the second frequency) or lower may be smaller than the magnitude of the component with the same frequency f 32 or lower of the acoustic signals AC1-1 and AC2-1 (the first acoustic signal and the second acoustic signal) emitted from the driver unit 11-1 (the first driver unit). For example, the driver unit 11-2 may output the acoustic signals AC2-2 and AC1-2 in which the frequency band with a frequency f 32 or lower is suppressed. Specific examples of the frequency f 32 are 1000 Hz, 2000 Hz, 3000 Hz, etc.

[0089] Example 31-3: For example, the magnitudes of the high-frequency sides of the acoustic signal AC2-2 and the acoustic signal AC1-2 may be suppressed more than the magnitudes of the high-frequency sides of the acoustic signal AC2-1 and the acoustic signal AC1-1, and the magnitudes of the low-frequency sides of the acoustic signal AC2-2 and the acoustic signal AC1-2 may be suppressed more than the magnitudes of the low-frequency sides of the acoustic signal AC2-1 and the acoustic signal AC1-1. For example, the driver unit 11-2 may output the acoustic signals AC2-2 and AC1-2 (e.g., acoustic signals AC2-2 and AC1-2 that only contain signals in the frequency band between the frequency f 32 and the following frequency band and the frequency f 31 where the acoustic signals AC2-2 and AC1-2 in the above frequency band are suppressed). 32 and the frequency f 31

[0090] A configuration example 3 of the circuit unit 31 for realizing these is illustrated below. As illustrated in FIG. 30C, the circuit unit 31 in this example includes a level correction unit 312, a phase control unit 313, a delay correction unit 314, and a band filter unit 315. The input signal input to the circuit unit 31 is input to the band filter unit 315 and the delay correction unit 314. The band filter unit 315 obtains and outputs a band-limited signal with the band of the input signal restricted (narrowed). In the case of the above example 31-1, a signal with the high-frequency side of the input signal (e.g., the frequency band of f 31 or higher) suppressed is output as the band-limited signal. In the case of the above example 31-2, a signal with the low-frequency side of the input signal (e.g., the frequency band of f 32 or lower) suppressed is output as the band-limited signal. In the case of the above example 31-3, a signal with the high-frequency side (e.g., the frequency band of f 31 or higher) and the low-frequency side (e.g., the frequency band of f 32 or lower) of the input signal suppressed is output as the band-limited signal.

[0091] ​The band-limited signal is input to the level correction unit 312. The level correction unit 312 adjusts the level of each band of the band-limited signal and outputs the band level-adjusted signal obtained thereby. The band level-adjusted signal output from the level correction unit 312 is input to the phase control unit 313. The phase control unit 313 generates an inverse phase signal of the band level-adjusted signal or an approximate signal of the inverse phase signal, and outputs this as output signal II. Output signal II is supplied to the driver unit 11-2. Also, the delay correction unit 314 outputs output signal I with the delay amount of the input input signal adjusted.

[0092] <Usage state> Using FIG. 31, the usage state of the acoustic signal output device 30 is illustrated. One acoustic signal output device 30 is mounted on each of the right ear 1010 and the left ear (not shown) of the user 1000 in FIG. 31. The D1 direction side of each of the acoustic signal output devices 10-1 of the acoustic signal output device 30 is directed toward the external auditory canal 1011 side of the user 1000. Further, the acoustic signal output device 10-2 is disposed at a position deviated from the external auditory canal 1011. For example, when the acoustic signal output device 30 is worn on the ear, the sound hole 121a-1 (first sound hole) is arranged facing the direction of the external auditory canal 1011, and the sound holes 123a-1 (second sound hole), 123a-2 (third sound hole), and 121a-2 (fourth sound hole) are arranged facing directions other than the external auditory canal 1011. An arbitrary mounting mechanism is used for mounting the acoustic signal output device 30 on the ear. The acoustic signal AC1-1 (first acoustic signal) emitted from the sound hole 121a-1 (first sound hole) of the acoustic signal output device 10-1 is listened to by the user 1000. On the other hand, a part of the acoustic signal AC2-1 (second acoustic signal) emitted from the sound hole 123a-1 (second sound hole) cancels out a part of the acoustic signal AC1-1 (first acoustic signal) emitted from the sound hole 121a-1 (first sound hole). Also, a part of the acoustic signal AC2-2 (third acoustic signal) emitted from the sound hole 123a-2 (third sound hole) cancels out a part of the acoustic signal AC1-2 (fourth acoustic signal) emitted from the sound hole 121a-2 (fourth sound hole). Further, a part of the acoustic signal AC2-2 (third acoustic signal) emitted from the sound hole 123a-2 (third sound hole) cancels out a part of the acoustic signal AC2-1 (second acoustic signal) emitted from the sound hole 123a-1 (second sound hole). Also, a part of the acoustic signal AC1-2 (fourth acoustic signal) emitted from the sound hole 121a-2 (fourth sound hole) cancels out a part of the acoustic signal AC1-1 (first acoustic signal) emitted from the sound hole 121a-1 (first sound hole). That is, in the present embodiment, the acoustic signal AC1-1 (first acoustic signal) is emitted from the sound hole 121a-1 (first sound hole), the acoustic signal AC2-1 (second acoustic signal) is emitted from the sound hole 123a-1 (second sound hole), the acoustic signal AC2-2 (third acoustic signal) is emitted from the sound hole 123a-2 (third sound hole), and the acoustic signal AC1-2 (fourth acoustic signal) is emitted from the sound hole 121a-2 (fourth sound hole). In this case, the attenuation rate η of the acoustic signal AC1-1 (first acoustic signal) at the position P2 (second point) with respect to the position P1 (first point)11 is the attenuation rate η due to air propagation of the acoustic signal at position P2 (second location) with respect to position P1 (first location). 21 is less than a predetermined value η th as follows. Or, in this case, the attenuation amount η of the acoustic signal AC1-1 (first acoustic signal) at position P2 (second location) with respect to position P1 (first location). 12 is the attenuation amount η due to air propagation of the acoustic signal at position P2 (second location) with respect to position P1 (first location). 22 is greater than a predetermined value ω th as follows. Note that in this embodiment, position P1 (first location) is a predetermined location where the acoustic signal AC1-1 (first acoustic signal) emitted from the sound hole 121a-1 (first sound hole) arrives. On the other hand, in this embodiment, position P2 (second location) is a predetermined location that is farther from the acoustic signal output device 30 than position P1 (first location). Thus, the sound leakage component from the acoustic signal output device 30 is canceled out. In particular, in this embodiment, since the relative level of the driver unit 11-2 with respect to the driver unit 11-1 can be controlled, sound leakage can be reduced more compared to the case of using one driver unit 11 as in the first embodiment.

[0093] Also, as described in Configuration Example 3 of the circuit unit 31, when allowing the user to listen to the acoustic signal AC1 emitted from the sound hole 121a-1 of the acoustic signal output device 10-1, by restricting the frequency band of the acoustic signal emitted from the acoustic signal output device 10-2 to be narrower than the frequency band of the acoustic signal emitted from the acoustic signal output device 10-1, a sufficient sound leakage suppression effect can be expected. For example, as in Example 31-1, when the magnitudes of the high-frequency sides (e.g., the high-frequency sides where it is difficult to suppress sound leakage by cancellation) of the acoustic signal AC2-2 and the acoustic signal AC1-2 are suppressed more than the magnitudes of the high-frequency sides of the acoustic signal AC2-1 and the acoustic signal AC1-1, it is possible to suppress the situation where sound leakage is rather promoted on the high-frequency side. Also, for example, as in Example 31-2, even if the magnitudes of the low-frequency sides of the acoustic signal AC2-2 and the acoustic signal AC1-2 are suppressed more than the magnitudes of the low-frequency sides of the acoustic signal AC2-1 and the acoustic signal AC1-1, in applications where the level of the low-frequency sound range such as earphones is weak, the influence of sound leakage is small. Further, even if the driver unit 11-2 is smaller or has lower performance than the driver unit 11-1, a sufficient sound leakage suppression effect can be expected.

[0094] [Modification Example 1 of the Third Embodiment] The acoustic signal output devices 10-1 and 10-2 may be the acoustic signal output device 10 described in the modification of the first embodiment. For example, as illustrated in FIG. 32A, the position of the sound hole 121a-1 (first sound hole) may be offset to a first eccentric position (a position on an axis A12-1 parallel to the axis A1-1 offset from the axis A1-1) that is offset from the axis A1-1 (first central axis) extending in the direction D1-1 (first direction) through the central region of the housing 12-1 (first housing portion). Further, as illustrated in FIG. 32B, when the circumference C1-1 (first circumference) is equally divided into a plurality of first unit arc regions, the sum of the opening areas of the sound holes 123a-1 (second sound holes) provided along any one of the first arc regions, which are any of the first unit arc regions, may be smaller than the sum of the opening areas of the sound holes 123a-1 (second sound holes) provided along any one of the second arc regions, which are first unit arc regions closer to the first eccentric position than the first arc region. Similarly, for example, the position of the sound hole 121a-2 (fourth sound hole) may be offset to a fourth eccentric position (a position on an axis A12-2 parallel to the axis A1-2 offset from the axis A1-2) that is offset from the axis A1-2 (second central axis) extending in the direction D1-2 (fourth direction) through the central region of the housing 12-2 (second housing portion). Further, as illustrated in FIG. 32B, when the circumference C1-2 (fourth circumference) is equally divided into a plurality of second unit arc regions, the sum of the opening areas of the sound holes 121a-2 (fourth sound holes) provided along any one of the third arc regions, which are any of the second unit arc regions, may be smaller than the sum of the opening areas of the fourth sound holes provided along any one of the fourth arc regions, which are second unit arc regions closer to the fourth eccentric position than the third arc region. Even in such a case, preferably, the sound hole 121a-1 (first sound hole) and the sound hole 121a-2 (fourth sound hole) are preferably plane-symmetric or substantially plane-symmetric with respect to a reference plane P31 including a straight line (axis A1-1) extending in the direction D1-1 (first direction) and parallel or substantially parallel thereto. Similarly, the sound hole 123a-1 (second sound hole) and the sound hole 123a-2 (third sound hole) are preferably plane-symmetric or substantially plane-symmetric with respect to the reference plane P31. More preferably, the housing 12-1 (first housing portion) and the housing 12-2 (second housing portion) are preferably plane-symmetric or substantially plane-symmetric with respect to the reference plane P31.Further, the sound absorption material described in the modification of the first embodiment may be provided in at least one of the acoustic signal output devices 10-1 and 10-2.

[0095] [Modification 2 of the Third Embodiment] In the third embodiment, the housing 12-1 (first housing part) of the acoustic signal output device 10-1 and the housing 12-2 (second housing part) of the acoustic signal output device 10-2 may be integrated. For example, as illustrated in FIG. 33A, the housing 12-1 of the acoustic signal output device 10-1 and the housing 12-2 of the acoustic signal output device 10-2 are replaced with an integrated housing 12”, and a region AR31 in which the driver unit 11-1 is housed and a region AR32 in which the driver unit 11-2 is housed are partitioned by a wall portion 351 provided inside the housing 12”, and the region AR31 may be separated from the region AR32. When the region AR31 and the region AR32 are partitioned by the wall portion 351, inside the housing 12”, it is possible to suppress a part of the acoustic signal AC1-1 and a part of the acoustic signal AC1-2 from canceling each other out, and a part of the acoustic signal AC2-1 and a part of the acoustic signal AC2-2 from canceling each other out. Therefore, it is desirable that the region AR31 and the region AR32 are partitioned by the wall portion 351. However, the region AR31 and the region AR32 do not necessarily have to be partitioned by the wall portion 351. That is, a part of the acoustic signals AC1-1 and AC2-1 emitted from the driver unit 11-1 may not be emitted from any of the sound holes 121a-1, 123a-1, 121a-2, 123a-2 and may be canceled out by a part of the acoustic signals AC1-2 and AC2-2 emitted from the driver unit 11-2 inside the housing 12”. Even in this case, the components of the acoustic signals AC1-1, AC2-1, AC1-2, and AC2-2 that are not canceled out inside the housing 12” are emitted to the outside through any of the sound holes 121a-1, 123a-1, 121a-2, 123a-2. For example, the components of the acoustic signals AC1-1 and AC2-1 emitted from the driver unit 11-1 that are not canceled out inside the housing 12” are emitted to the outside through any of the sound holes 121a-1, 123a-1, 121a-2, 123a-2. Needless to say, they may be canceled out by a part of the components of other acoustic signals emitted from any of the driver units 11-1 and 2 and emitted to the outside through any of the sound holes 121a-1, 123a-1, 121a-2, 123a-2. Therefore, even in such a case, an effect of suppressing sound leakage can be obtained.Even when the housing 12-1 and the housing 12-2 are integrated as the housing 12”, it is desirable that the sound holes 121a-1 (the first sound hole) and the sound holes 121a-2 (the fourth sound hole) are plane-symmetrical or substantially plane-symmetrical with respect to the reference plane P31. Similarly, it is desirable that the sound holes 123a-1 (the second sound hole) and the sound holes 123a-2 (the third sound hole) are plane-symmetrical or substantially plane-symmetrical with respect to the reference plane P31. More preferably, it is desirable that the housing 12-1 (the first housing part) and the housing 12-2 (the second housing part) are plane-symmetrical or substantially plane-symmetrical with respect to the reference plane P31. Further, the sound-absorbing material described in the modification example of the first embodiment may be provided inside the housing 12” or in any of the sound holes 121a-1, 121a-2, 123a-1, 123a-2. The rest is the same as that of the third embodiment or its modification example 1.

[0096] [Modification Example 3 of the Third Embodiment] Instead of the acoustic signal output devices 10-1 and 10-2 of the third embodiment, acoustic signal output devices 20-1 and 20-2 having the same configuration as the acoustic signal output device 20 of the second embodiment may be used. For example, as illustrated in FIG. 33B, the housing 22-1 and the housing 22-2 of the acoustic signal output devices 20-1 and 20-2 are joined by a connecting portion 32, and as described in the second embodiment, the housing 22-1 and the housing 23-1 are connected by waveguides 24-1 and 25-1, and the housing 22-2 and the housing 23-2 may be connected by waveguides 24-2 and 25-2. The circuit unit 31 supplies the output signal I to the driver unit 11-1 housed in the housing 23-1 and supplies the output signal II to the driver unit 11-2 housed in the housing 23-2. As described in the second embodiment, the acoustic signal AC1-1 sent from the housing 23-1 to the housing 22-1 through the waveguides 24-1 and 25-1 is emitted from the sound hole 221a-1, and the acoustic signal AC2-1 is emitted from the sound hole 223a-1. Similarly, the acoustic signal AC1-2 sent from the housing 23-2 to the housing 22-2 through the waveguides 24-2 and 25-2 is emitted from the sound hole 221a-2, and the acoustic signal AC2-2 is emitted from the sound hole 223a-2. Other matters are the same as those of the third embodiment or its modified examples 1 and 2, except that the housings 12-1 and 12-2, the sound holes 121a-1, 121a-2, 123a-1, and 123a-2, and the wall portions 121-1, 121-2, 122-1, 122-2, 123-1, and 123-2 are replaced with the housings 22-1 and 22-2, the sound holes 221a-1, 221a-2, 223a-1, and 223a-2, and the wall portions 221-1, 221-2, 222-1, 222-2, 223-1, and 223-2. Additionally, the housing 23-1 may be connected to the housing 22-1 by the waveguides 24-1 and 25-1 and to the housing 23-1 by the waveguides 24-2 and 25-2. In this case, the circuit unit 31 supplies the output signal I to the driver unit 11-1 housed in the housing 23-1. The acoustic signal AC1-1 sent from the housing 23-1 to the housing 22-1 through the waveguides 24-1 and 25-1 is emitted from the sound hole 221a-1, and the acoustic signal AC2-1 is emitted from the sound hole 223a-1. Similarly, the acoustic signal AC1-2 sent from the housing 23-1 to the housing 22-2 through the waveguides 24-2 and 25-2 is emitted from the sound hole 221a-2, and the acoustic signal AC2-2 is emitted from the sound hole 223a-2.Alternatively, the housing 23-1 may be connected to κ housings 22-κ by waveguides 24-κ and 25-κ. However, κ = 1, …, κ. max where κ max is an integer of 2 or more. In this case, the circuit unit 31 supplies the output signal I to the driver unit 11-1 housed in the housing 23-1. The acoustic signal AC1-κ sent from the housing 23-1 to the housing 22-κ through the waveguides 24-κ and 25-κ is emitted from the sound hole 221a-κ, and the acoustic signal AC2-κ is emitted from the sound hole 223a-κ. In such a case, the housing 23-2 and the driver unit 11-2 may be omitted, and the circuit unit 31 may not output the output signal II. Alternatively, the housing 23-2 and the driver unit 11-2 may not be omitted, and the housing 23-2 may be further connected to another housing 22-γ by waveguides 24-γ and 25-γ. However, γ = κ max + 1, …, γ max where γ max is κ maxis an integer greater than. In this case, the output signal II further output from the circuit unit 31 is supplied to the driver unit 11-2 housed in the housing 22-2, and the acoustic signal AC1-γ sent from the housing 23-2 to the housing 22-γ through the waveguides 24-γ and 25-γ is emitted from the sound hole 221a-γ, and the acoustic signal AC2-γ is emitted from the sound hole 223a-γ. That is, it is only necessary that the acoustic signal AC1-1 (first acoustic signal) emitted from any one of the single or plural driver units is emitted to the outside from the sound hole 221a-1 (first sound hole). Also, it is only necessary that the acoustic signal AC2-1 (second acoustic signal) emitted from any one of the single or plural driver units is emitted to the outside from the sound hole 123a-1 (second sound hole). Also, it is only necessary that the acoustic signal AC2-2 (third acoustic signal) emitted from any one of the single or plural driver units is emitted from the sound hole 123a-2 (third sound hole). Also, it is only necessary that the acoustic signal AC1-2 (fourth acoustic signal) emitted from any one of the single or plural driver units is emitted to the outside from the sound hole 221a-2 (fourth sound hole). That is, the acoustic signal AC1-1 (first acoustic signal) and the acoustic signal AC2-2 (third acoustic signal) may be the same signal emitted from the same driver unit, or they may be different signals emitted from different driver units. Similarly, the acoustic signal AC2-1 (second acoustic signal) and the acoustic signal AC1-2 (fourth acoustic signal) may be the same signal emitted from the same driver unit, or they may be different signals emitted from different driver units.

[0097] [Fourth Embodiment] In the fourth embodiment, an example is shown in which an acoustic signal output device worn on both ears without sealing the user's external auditory canals emits monaural acoustic signals whose phases are inverted with respect to each other toward the left and right ears. From such an acoustic signal output device, not only to the user's external auditory canal side but also to the outside of the user, a part of the monaural acoustic signal is emitted. However, since monaural acoustic signals whose phases are inverted with respect to each other are emitted, the monaural acoustic signals propagating to the outside of the user cancel each other out, and sound leakage is reduced.

[0098] As illustrated in FIG. 34A, the acoustic signal output device 4 of the present embodiment includes an acoustic signal output unit 40-1 (first acoustic signal output unit) attached to the right ear (one ear) 1010 of the user 1000, an acoustic signal output unit 40-2 (second acoustic signal output unit) attached to the left ear (the other ear) 1020, and a circuit unit 41.

[0099] <circuit unit 41> The circuit unit 41 is a circuit that uses an input signal, which is an electrical signal representing a monaural acoustic signal, as an input, and generates and outputs an output signal I supplied to the acoustic signal output unit 40-1 and an output signal II supplied to the acoustic signal output unit 40-2. The circuit unit 41 of the present embodiment includes signal output units 411 and 412 and a phase inversion unit 413. The input signal is input to the phase inversion unit 413 and the signal output unit 412. The phase inversion unit 413 outputs an output signal I (first output signal), which is an inverted phase signal of the input signal or an approximate signal of the inverted phase signal. The signal output unit 411 (first signal output unit) outputs the output signal I (first output signal) to the acoustic signal output unit 40-1 (first acoustic signal output unit). That is, the signal output unit 411 (first signal output unit) outputs an output signal I (first output signal) for outputting a monaural acoustic signal MAC1 (first monaural acoustic signal) from the acoustic signal output unit 40-1 (first acoustic signal output unit) attached to the right ear (one ear) 1010. The signal output unit 412 outputs the input signal as it is as an output signal II (second output signal) to the acoustic signal output unit 40-2 (second acoustic signal output unit). That is, the signal output unit 412 outputs an output signal II (second output signal) for outputting a monaural acoustic signal MAC2 (second monaural acoustic signal) from the acoustic signal output unit 40-2 (second acoustic signal output unit) attached to the left ear (the other ear) 1020.

[0100] <acoustic signal output units 40-1 and 40-2> The acoustic signal output units 40-1 and 40-2 are devices for acoustic listening that are worn on both ears without sealing the user's ear canals. An output signal I is input to the acoustic signal output unit 40-1, and the acoustic signal output unit 40-1 converts the output signal I into a monaural acoustic signal MAC1 (the phase that is the same or substantially the same as the phase of the monaural acoustic signal MAC1 is expressed as “+”) and emits it toward the ear canal of the right ear 1010. An output signal II is input to the acoustic signal output unit 40-2, and the acoustic signal output unit 40-2 converts the output signal II into a monaural acoustic signal MAC2 (the phase that is the same or substantially the same as the phase of the monaural acoustic signal MAC2 is expressed as “-”) and emits it toward the ear canal of the left ear 1020. Here, the monaural acoustic signal MAC2 is an inverse phase signal of the monaural acoustic signal MAC1 or an approximate signal of the inverse phase signal of the monaural acoustic signal MAC1. However, even if the phases of the acoustic signals perceived by the left and right ears are inverted with respect to each other, almost no viewing problems occur. Also, although a part of the emitted monaural acoustic signal MAC1 and the monaural acoustic signal MAC2 is also emitted outside both ears, since the monaural acoustic signal MAC1 and the monaural acoustic signal MAC2 are in inverse phase or substantially inverse phase with respect to each other, they cancel each other out. That is, a part of the emitted monaural acoustic signal MAC1 (the first monaural acoustic signal) and a part of the emitted monaural acoustic signal MAC2 (a part of the second monaural acoustic signal) cancel each other out by interfering with each other outside the acoustic signal output unit 40-1 (the first acoustic signal output unit) worn on the right ear 1010 (one ear), and / or outside the acoustic signal output unit 40-2 (the second acoustic signal output unit) worn on the left ear 1020 (the other ear) (the outside of the user 1000, that is, the opposite side of the right ear 1010 side, and / or the outside of the left ear 1020 side). That is, as described above, the monaural acoustic signal MAC1 (the first monaural acoustic signal) is output from the acoustic signal output unit 40-1 (the first acoustic signal output unit), and the monaural acoustic signal MAC2 (the second monaural acoustic signal) is output from the acoustic signal output unit 40-2 (the second acoustic signal output unit). In this case, the attenuation rate η of the monaural acoustic signal MAC1 (the first monaural acoustic signal) at the position P2 (the second point) based on the position P1 (the first point) 11 is the attenuation rate η due to air propagation of the acoustic signal at the position P2 (the second point) based on the position P1 (the first point)21 less than a predetermined value η th is as follows. Alternatively, the attenuation amount η of the first monaural acoustic signal at the position P2 (second point) with respect to the position P1 (first point) in this case 12 is greater than the attenuation amount η due to air propagation of the acoustic signal at the position P2 (second point) with respect to the position P1 (first point). 22 greater than a predetermined value ω th is as follows. However, the position P1 (first point) in the present embodiment is a predetermined position where the monaural acoustic signal MAC1 (first monaural acoustic signal) arrives. Also, the position P2 (second point) in the present embodiment is a position farther from the acoustic signal output unit 40-1 (first acoustic signal output unit) than the position P1 (first point). As a result, sound leakage is suppressed.

[0101] [Modification Example 1 of the Fourth Embodiment] Instead of the acoustic signal output units 40-1 and 40-2, the acoustic signal output device 10 of the first embodiment or its modification example may be used, or the acoustic signal output device 20 of the second embodiment or its modification example may be used.

[0102] As illustrated in FIG. 34B, the acoustic signal output device 4' of this modification example includes an acoustic signal output device 10-1 (first acoustic signal output unit) worn on the right ear (one ear) 1010 of the user 1000, an acoustic signal output device 10-2 (second acoustic signal output unit) worn on the left ear (the other ear) 1020, and a circuit unit 41, or an acoustic signal output device 20-1 (first acoustic signal output unit) worn on the right ear (one ear) 1010 of the user 1000, an acoustic signal output device 20-2 (second acoustic signal output unit) worn on the left ear (the other ear) 1020, and a circuit unit 41.

[0103] The audio signal output device 10-1 or 20-1 (first audio signal output unit) emits a monaural audio signal MAC1-1 (first audio signal, first monaural audio signal) in the D1-1 direction (one side), and emits a monaural audio signal MAC2-1 (second audio signal), which is an inverted phase signal of the monaural audio signal MAC1-1 or an approximate signal of the inverted phase signal of the monaural audio signal MAC1-1, in the other side of the D1-1 direction. It includes a driver unit 11-1 (first driver unit), one or more sound holes 121a-1 or 221a-1 (first sound holes) for guiding the monaural audio signal MAC1-1 (first audio signal) emitted from the driver unit 11-1 to the outside, and one or more sound holes 123a-1 or 223a-1 (second sound holes) for guiding the monaural audio signal MAC2-1 (second audio signal) emitted from the driver unit 11-1 to the outside, and a housing 12-1 or 22-1 (first housing) provided on the wall portion.

[0104] The audio signal output device 10-2 or 20-2 (second audio signal output unit) emits a monaural audio signal MAC1-2 (fourth audio signal, second monaural audio signal) that is the same as or approximate to the monaural audio signal MAC2-1 (second audio signal) in the D1-2 direction (one side), and emits a monaural audio signal MAC2-2 (third audio signal) that is the same as or approximate to the monaural audio signal MAC1-1 (first audio signal) in the other side of the D1-2 direction. It includes a driver unit 11-2 (second driver unit), one or more sound holes 123a-2 or 223a-2 (third sound holes) for guiding the monaural audio signal MAC2-2 (third audio signal) emitted from the driver unit 11-2 to the outside, and one or more sound holes 121a-2 or 221a-2 (fourth sound holes) for guiding the monaural audio signal MAC1-2 (fourth audio signal) emitted from the driver unit 11-2 to the outside, and a housing 12-2, 22-2 (second housing) provided on the wall portion.

[0105] In this modified example, the acoustic signal AC1-1 (first acoustic signal) is a monaural acoustic signal MAC1-1 (first monaural acoustic signal), the acoustic signal AC2-1 is a monaural acoustic signal MAC2-1, the acoustic signal AC1-2 (fourth acoustic signal) is a monaural acoustic signal MAC1-2 (second monaural acoustic signal), and the acoustic signal AC2-2 is a monaural acoustic signal MAC2-2. The detailed configurations of the other acoustic signal output devices 10-1 and 10-2 are the same as those of the acoustic signal output device 10 in the first embodiment or its modified example. Also, the detailed configurations of the acoustic signal output devices 20-1 and 20-2 are the same as those of the acoustic signal output device 20 in the second embodiment or its modified example.

[0106] When the acoustic signal output device 4' is worn on both ears, the sound holes 121a-1 or 221a-1 of the acoustic signal output device 10-1 or 20-1 are directed toward the right ear 1010 (i.e., the direction D1-1 is directed toward the right ear 1010), and the sound holes 121a-2 or 221a-2 of the acoustic signal output device 10-2 or 20-2 are directed toward the left ear 1020 (i.e., the direction D1-2 is directed toward the left ear 1020).

[0107] From the sound holes 121a-1 or 221a-1 of the audio signal output device 10-1 or 20-1 (the first audio signal output unit), the monaural audio signal MAC1-1 (the first monaural audio signal) is emitted toward the external auditory canal of the right ear 1010. From the sound holes 121a-2 or 221a-2 of the audio signal output device 10-2 or 20-2 (the second audio signal output unit), the monaural audio signal MAC1-2 (the second monaural audio signal) is emitted toward the external auditory canal of the left ear 1020. Here, the monaural audio signal MAC1-2 is the inverted phase signal of the monaural audio signal MAC1-1 or an approximate signal of the inverted phase signal of the monaural audio signal MAC1-1. However, even if the phases of the audio signals perceived by the left and right ears are inverted with respect to each other, almost no problems occur in terms of viewing and listening. Also, although a part of the emitted monaural audio signal MAC1-1 and the monaural audio signal MAC1-2 is also emitted outside both ears, since the monaural audio signal MAC1-1 and the monaural audio signal MAC1-2 are in opposite phases or substantially opposite phases to each other, they cancel each other out. That is, a part of the emitted monaural audio signal MAC1-1 (the first monaural audio signal) and a part of the emitted monaural audio signal MAC1-2 (a part of the second monaural audio signal) are on the outer side of the audio signal output device 10-1 or 20-1 (the first audio signal output unit) attached to the right ear 1010 (one ear), i.e., on the outer side of the user 1000 (the side opposite to the right ear 1010 side), and / or on the outer side of the audio signal output device 10-2 or 20-2 (the second audio signal output unit) attached to the left ear 1020 (the other ear), i.e., on the outer side of the user 1000 (the side opposite to the left ear 1020 side), and they cancel each other out by interfering with each other. Further, from the sound holes 123a-1 or 223a-1 of the audio signal output device 10-1 or 20-1 (the first audio signal output unit), the monaural audio signal MAC2-1 is emitted. A part of the emitted monaural audio signal MAC2-1 cancels out a part of the monaural audio signal MAC1-1 emitted from the sound holes 121a-1 or 221a-1. Also, from the sound holes 123a-2 or 223a-2 of the audio signal output device 10-2 or 20-2 (the second audio signal output unit), the monaural audio signal MAC2-2 is emitted. A part of the emitted monaural audio signal MAC2-2 cancels out a part of the monaural audio signal MAC1-2 emitted from the sound holes 121a-2 or 221a-2.As a result, sound leakage is suppressed.

[0108] [Modification Example 2 of the Fourth Embodiment] In the fourth embodiment or modification example 1 of the fourth embodiment, the output signal I and the output signal II may be reversed. That is, the input signal input to the circuit unit 41 is input to the phase inversion unit 413 and the signal output unit 412, and the phase inversion unit 413 outputs the output signal II (second output signal), which is the inverted phase signal of the input signal or an approximate signal of the inverted phase signal, to the acoustic signal output unit 40-2 (second acoustic signal output unit), and the signal output unit 412 may output the input signal as it is as the output signal I (first output signal) to the acoustic signal output unit 40-1 (first acoustic signal output unit).

[0109] [Fifth Embodiment] In the fifth embodiment, the wearing method of the ear-mounted acoustic signal output device will be exemplified. As described above, in the conventional wearing method, problems such as a large burden on the ear or difficulty in stable wearing may occur. In this embodiment, a new wearing method of the acoustic signal output device for solving such problems will be exemplified.

[0110] [Wearing Method 1] Wearing method 1 will be exemplified with reference to FIGS. 35A to 36D. As illustrated in FIGS. 35A to 35C, the acoustic signal output device 2100 of wearing method 1 includes a housing 2112 that emits an acoustic signal, a mounting portion 2121 (first mounting portion) that holds the housing 2112 and is configured to be mounted on the upper portion 1022 (first auricle portion) of the auricle 1020, which is a part of the auricle 1020, and a mounting portion 2122 (second mounting portion) that holds the housing 2112 and is configured to be mounted on an intermediate portion 1023 (second auricle portion) of the auricle 1020, which is a part of the auricle 1020 different from the upper portion 1022 (first auricle portion) of the auricle 1020. Note that the intermediate portion 1023 is an intermediate portion between the upper portion 1022 (helix side) and the lower portion 1024 (earlobe side) of the auricle 1020. In addition, in this embodiment, an example in which the auricle 1020 is a human auricle is shown, but the auricle 1020 may be an auricle of an animal other than a human (such as a chimpanzee).

[0111] The housing 2112 in this example may be any of the housings 12, 12", 22 exemplified in the first to fourth embodiments and their modifications, or may be the housing of an acoustic signal output device that emits an acoustic signal such as a conventional earphone. When the acoustic signal output device 2100 is worn, the housing 2112 is arranged such that the sound hole 2112a faces the external auditory canal 1021 side and the external auditory canal 1021 is not blocked.

[0112] The wearing part 2121 (first wearing part) in this example has a fixing part 2121a (first fixing part) that grips the helix 1022a (end part) of the upper part 1022 (first auricle part) of the auricle 1020, and a support part 2121b that fixes the fixing part 2121a (first fixing part) to the housing 2112. One end of the support part 2121b holds a specific area of the outer wall part of the fixing part 2121a, and the other end of the support part 2121b holds a specific area H1 (first holding area) of the outer wall part of the housing 2112. One end of the support part 2121b may be fixed to a specific area of the wall part of the fixing part 2121a, or may be integrated with the wall part of the fixing part 2121a in the specific area. Similarly, the other end of the support part 2121b may be fixed to the specific area H1 of the outer wall part of the housing 2112, or may be integrated with the outer wall part of the housing 2112 in the specific area H1. In this way, the support part 2121b holds the housing 2112 from the outer side (first outer side) of the specific area H1 of the wall part of the housing 2112. In the case of this example, when the fixing part 2121a is attached to the helix 1022a, the outer side (first outer side) of the area H1 becomes the upper part 1022 side of the auricle 1020. Here, the fixing part 2121a (first fixing part) is configured to grip the helix 1022a of the upper part 1022 (first auricle part) of the auricle 1020 from above the auricle 1020. Further, the housing 2112 is configured to be suspended by the wearing part 2121 (first wearing part) including the fixing part 2121a that grips the helix 1022a. That is, the fixing part 2121a grips the helix 1022a from above the auricle 1020, and the housing 2112 is suspended by the other end of the support part 2121b that holds the fixing part 2121a at one end. The reaction force against the weight of the housing 2112 suspended in this way is supported by the inner wall surface of the fixing part 2121a. For example, this reaction force is supported by the inner wall surface of the fixing part 2121a that is arranged perpendicular or substantially perpendicular to the reaction force direction. In the case of such a configuration, even if the gripping force of the fixing part 2121a is small, the weight of the housing 2112 can be supported. The smaller the gripping force of the fixing part 2121a, the smaller the burden on the auricle 1020, so the burden on the ear can be reduced. Note that the specific shape of the fixing part 2121a may be any shape.An example of the fixing portion 2121a is a member having a hollow shape with a C-shaped or U-shaped cross-sectional shape, and is configured to grip the earring 1022a in a state where the earring 1022a is in contact with the inner wall surface 2121aa (for example, FIGS. 36A to 36D). For example, the fixing portion 2121a having an ear cuff type shape can be exemplified.

[0113] The wearing part 2122 (second wearing part) in this example has a fixing part 2122a (second fixing part) that grips the end of the middle part 1023 (second auricle part) of the auricle 1020, and a support part 2122b that fixes the fixing part 2122a to the housing 2112. One end of the support part 2122b holds a specific area of the outer wall part of the fixing part 2122a, and the other end of the support part 2122b holds a specific area H2 (second holding area) of the outer wall part of the housing 2112. The area H2 is different from the above-mentioned area H1. One end of the support part 2122b may be fixed to a specific area of the wall part of the fixing part 2122a, or may be integrated with the wall part of the fixing part 2122a in the specific area. Similarly, the other end of the support part 2122b may be fixed to a specific area H2 of the outer wall part of the housing 2112, or may be integrated with the outer wall part of the housing 2112 in the specific area H2. In this way, the support part 2122 holds the housing 2112 from the outer side (second outer side different from the first outer side) of the specific area H2 of the wall part of the housing 2112. In the case of this example, when the fixing part 2122a is attached to the end of the middle part 1023 of the auricle 1020, the outer side (second outer side) of the area H2 becomes the middle part 1023 side of the auricle 1020. In this way, the housing 2112 is held on the upper part 1022 of the auricle 1020 from the outer side (first outer side) of the area H1 by the wearing part 2121 (first wearing part) as described above, and is further held on the middle part 1023 of the auricle 1020 from the outer side (second outer side different from the first outer side) of the area H2 by the wearing part 2122 (second wearing part). Thereby, the position of the housing 2112 attached to the auricle 1020 becomes stable. Also, since the housing 2112 is held by the wearing part 2121 (first wearing part) and the wearing part 2122 (second wearing part) at different parts (upper part 1022 and middle part 1023) of the auricle 1020, the burden on the auricle 1020 due to wearing can be dispersed. Furthermore, the housing 2112 is attached to the auricle 1020 by the wearing parts 2121 and 2122 that grip the ends of the auricle 1020. Such wearing parts 2121 and 2122 do not interfere with the temple of the glasses or the strap of the mask that are hooked on the back side of the auricle 1020. Note that the specific shape of the fixing part 2122a may be any shape.An example of the fixing part 2122a is a member having a hollow shape with a C-shaped or U-shaped cross-sectional shape, and is configured to grip the middle part 1023 of the auricle 1020 in a state where the earring 1022a is in contact with the inner wall surface 2122aa. For example, the fixing part 2122a having an ear cuff type shape can be exemplified.

[0114] There is no limitation on the material constituting the mounting part 2121 and the mounting part 2122. The mounting part 2121 and the mounting part 2122 may be constituted by a rigid body such as a synthetic resin or a metal, or may be constituted by an elastic body such as rubber.

[0115] <Mounting method 2> The mounting method 2 is exemplified with reference to FIGS. 37A to 37C. As illustrated in FIGS. 37A to 37C, the acoustic signal output device 2100' of the mounting method 2 is obtained by adding a mounting part 2123 (second mounting part) to the acoustic signal output device 2100 of the mounting method 1, and the mounting part 2123 is configured to be mounted on a lower part 1024 (second auricle part) of the auricle 1020, which is a part of the auricle 1020 different from the upper part 1022 (first auricle part) and the middle part 1023 (second auricle part) of the auricle 1020.

[0116] The mounting portion 2123 (second mounting portion) in this example has a fixing portion 2123a (second fixing portion) that grips the end of the lower portion 1024 (second auricle part) of the auricle 1020, and a support portion 2123b that fixes the fixing portion 2123a (second fixing portion) to the housing 2112. One end of the support portion 2123b holds a specific region of the outer wall portion of the fixing portion 2123a, and the other end of the support portion 2123b holds a specific region H3 (second holding region) of the outer wall portion of the housing 2112. The region H3 is different from the above-mentioned regions H1 and H2. One end of the support portion 2123b may be fixed to a specific region of the wall portion of the fixing portion 2123a, or may be integrated with the wall portion of the fixing portion 2123a in the specific region. Similarly, the other end of the support portion 2123b may be fixed to a specific region H3 of the outer wall portion of the housing 2112, or may be integrated with the outer wall portion of the housing 2112 in the specific region H3. In this way, the support portion 2123 holds the housing 2112 from the outer side (second outer side different from the first outer side) of the specific region H3 of the wall portion of the housing 2112. In the case of this example, when the fixing portion 2123a is mounted on the end of the lower portion 1024 of the auricle 1020, the outer side (second outer side) of the region H3 becomes the lower portion 1024 side of the auricle 1020. In this way, the housing 2112 is further held on the lower portion 1024 of the auricle 1020 from the outer side (second outer side different from the first outer side) of the region H3 by the mounting portion 2123 (second mounting portion). Thereby, the position of the housing 2112 mounted on the auricle 1020 becomes more stable. Also, since the housing 2112 is held by the mounting portion 2121 (first mounting portion), the mounting portion 2122 (second mounting portion), and the mounting portion 2123 (second mounting portion) at different parts of the auricle 1020 (upper portion 1022, middle portion 1023, and lower portion 1024), the burden on the auricle 1020 due to mounting can be dispersed. Furthermore, the housing 2112 is mounted on the auricle 1020 by the mounting portions 2121, 2122, 2123 that grip the ends of the auricle 1020. Such mounting portions 2121, 2122, 2123 do not interfere with the temples of glasses or the straps of a mask that are hooked on the back side of the auricle 1020. Note that the specific shape of the fixing portion 2123a may be any shape.An example of the fixing part 2123a has a hollow shape with a C-shaped or U-shaped cross-section, and is configured to grip the lower part 1024 of the auricle 1020 in a state where the earring 1022a is in contact with the inner wall surface 2123aa. For example, the fixing part 2123a having an ear cuff type shape can be exemplified. There is no limitation on the material constituting the mounting part 2123.

[0117] <Wearing method 3> The mounting part 2122 of the acoustic signal output device 2100' of the wearing method 2 may be omitted.

[0118] <Wearing method 4> Similar to the acoustic signal output device 2200 illustrated in FIG. 38, the mounting part 2121 of the acoustic signal output device 2100 of the wearing method 1 may be replaced with a mounting part 2224 of a type (a type of glasses temple) that is hooked on the back side of the upper part 1022 of the auricle 1020. The mounting part 2224 is a rod-shaped member. One end side of the mounting part 2224 is bent so as to be hooked on the back side of the upper part 1022 of the auricle 1020, and the other end holds a specific area H1 (first holding area) of the outer wall part of the housing 2112. The other end of the mounting part 2224 may be fixed to the specific area H1 of the outer wall part of the housing 2112, or may be integrated with the outer wall part of the housing 2112 in the specific area H1. Similarly, the mounting part 2121 of the acoustic signal output device 2100' of the wearing methods 2 and 3 may be replaced with the mounting part 2224 of the type that is hooked on the back side of the upper part 1022 of the auricle 1020. Note that there is no limitation on the material constituting the mounting part 2224.

[0119] <Wearing method 5> Similar to the acoustic signal output device 2300 illustrated in FIG. 39A, the mounting portion 2122 of the acoustic signal output device 2100 of mounting method 1 may be replaced with a mounting portion 2124 (second mounting portion) that sandwiches the end of the middle portion 1023 (second auricle site) of the auricle 1020. The mounting portion 2124 (second mounting portion) includes a fixing portion 2124a (second fixing portion) that sandwiches the end of the middle portion 1023 (second auricle site) of the auricle 1020, and a support portion 2124b that fixes the fixing portion 2124a (second fixing portion) to the housing 2112. One end of the support portion 2124b holds the end of the fixing portion 2124a, and the other end of the support portion 2124b holds a specific region H2 (second holding region) of the outer wall portion of the housing 2112. One end of the support portion 2124b may be fixed to the end of the fixing portion 2124a or may be integrated with the end of the fixing portion 2124a. Similarly, the other end of the support portion 2124b may be fixed to a specific region H2 of the outer wall portion of the housing 2112 or may be integrated with the outer wall portion of the housing 2112 in the specific region H2. In this way, the support portion 2124b holds the housing 2112 from the outer side (second outer side different from the first outer side) of the specific region H2 of the wall portion of the housing 2112. In this way, the housing 2112 is held on the upper portion 1022 of the auricle 1020 from the outer side (first outer side) of the region H1 by the mounting portion 2121 (first mounting portion) as described above, and further held on the middle portion 1023 of the auricle 1020 from the outer side (second outer side different from the first outer side) of the region H2 by the mounting portion 2124 (second mounting portion). Thereby, the position of the housing 2112 mounted on the auricle 1020 becomes stable. Also in this case, since the housing 2112 is held at different sites (upper portion 1022 and middle portion 1023) of the auricle 1020 by the mounting portion 2121 (first mounting portion) and the mounting portion 2124 (second mounting portion), the burden on the auricle 1020 due to mounting can be dispersed. Further, the mounting portions 2121 and 2124 do not interfere with the temples of glasses or the straps of a mask that are hooked on the back side of the auricle 1020. In addition, the sandwiching fixing portion 2124a (second fixing portion) may be configured to sandwich the lower portion 1024 of the auricle 1020 instead of the middle portion 1023 of the auricle 1020. Note that the specific shape of the fixing portion 2124a may be any shape.For example, the fixing portion 2124a may be a clip-shaped clamping mechanism or an integrated leaf spring. Also, the material constituting the mounting portion 2124 is not limited either.

[0120] <Mounting method 6> Similar to the acoustic signal output device 2400 illustrated in FIG. 39B, the mounting portion 2121 of the acoustic signal output device 2300 of mounting method 5 may be replaced with a mounting portion 2224 of the type that is hooked on the back side of the upper portion 1022 of the auricle 1020. The configuration of the mounting portion 2224 is the same as that of mounting method 4.

[0121] <Mounting method 7> When the housing 2112 is the housings 12, 12", 22 exemplified in the first to fourth embodiments and their modified examples, the opening area of the sound hole 123a, 223a (second sound hole) provided in the region (shielding region) shielded by the mounting portions 2121, 2122, 2123, 2124, 2224 or in the vicinity thereof from the sound hole 121a, 221a (first sound hole) of the housings 12, 12", 22 may be made smaller than the opening area of the sound hole 123a, 223a (second sound hole) provided at a position away from the shielding region. As described above, a part of the acoustic signal AC1 (first acoustic signal) emitted from the sound hole 121a, 221a (first sound hole) of the housings 12, 12", 22 is canceled out by the acoustic signal AC2 (second acoustic signal) emitted from the sound hole 123a, 223a (second sound hole), thereby suppressing sound leakage. Here, in the shielding region, the sound pressure of the acoustic signal AC1 (first acoustic signal) leaking to the outside is smaller than that in other regions. In accordance with this, by reducing the opening area of the sound hole 123a, 223a (second sound hole) provided in the shielding region or in the vicinity thereof, it is possible to balance the distribution of the sound pressure of the acoustic signal AC1 (first acoustic signal) leaking to the outside and the distribution of the sound pressure of the acoustic signal AC2 (second acoustic signal) emitted from the sound hole 123a, 223a (second sound hole). That is, the acoustic signal AC1 (first acoustic signal) is emitted from the sound hole 121a, 221a (first sound hole), and the acoustic signal AC2 (second acoustic signal) is emitted from the sound hole 123a, 223a (second sound hole). In this case, the attenuation rate η 11 of the acoustic signal AC1 (first acoustic signal) at the position P2 (second point) based on the position P1 (first point) 21 is smaller than a predetermined value η th of the attenuation rate of the acoustic signal due to air propagation at the position P2 (second point) based on the position P1 (first point). In this way, the balance of the sound pressure distribution can be achieved. Or, in this case, the attenuation amount η 12 of the acoustic signal AC1 (first acoustic signal) at the position P2 (second point) based on the position P1 (first point) 22 is larger than a predetermined value ω thIn this way, the balance of the sound pressure distribution can be achieved. Here, the position P1 (the first point) is a predetermined point where the acoustic signal AC1 (the first acoustic signal) emitted from the sound hole 221a (the first sound hole) arrives. Also, the position P2 (the second point) here is a predetermined point that is farther from the acoustic signal output device than the position P1 (the first point). As a result, sound leakage can be effectively suppressed.

[0122] Hereinafter, an example will be described in which the housing 2112 is the housing 12 of the first embodiment or a modified example thereof, and this housing 12 (housing 2112) is held by the mounting portions 2121 and 2122 of the mounting method 1. However, this does not limit the present invention. The housing 2112 may be the housing 12, 12", 22 exemplified in the second to fourth embodiments and their modified examples, and this housing 12, 12", 22 may be held by any of the mounting portions 2121, 2122, 2123, 2124, 2224 of the mounting methods 2 to 6. Even in this case, the following configuration can be applied.

[0123] As illustrated in FIG. 40A, in this case, the acoustic signal output device 2100 has a driver unit 11 that emits an acoustic signal AC1 (first acoustic signal) to one side (D1 direction side) and emits an acoustic signal AC2 (second acoustic signal), which is an inverted phase signal of the acoustic signal AC1 (first acoustic signal) or an approximate signal of the inverted phase signal, to the other side (D2 direction side). As described above, on the wall portions 121 and 123 of the housing 12, there are provided one or more sound holes 121a (first sound holes) for guiding the acoustic signal AC1 (first acoustic signal) emitted from the driver unit 11 to the outside, and one or more sound holes 123a (second sound holes) for guiding the acoustic signal AC2 (second acoustic signal) emitted from the driver unit 11 to the outside. As described above, part of the acoustic signal AC2 (second acoustic signal) emitted from the sound hole 123a (second sound hole) cancels out part of the acoustic signal AC1 (first acoustic signal) emitted from the sound hole 121a (first sound hole), thereby suppressing sound leakage. As described above, the support portion 2121b of the mounting portion 2121 (first mounting portion) holds the region H1 (first holding region) of the wall portion 123 of the housing 12 (housing 2112), and the support portion 2122b of the mounting portion 2122 (second mounting portion) holds the region H2 (second holding region) of the wall portion 123 of the housing 12 (housing 2112). Here, the sound hole 121a (first sound hole) is disposed on one side (D1 direction side) of the space partitioned by the virtual plane P51 passing through the region H1 (first holding region) and the mounting portion 2122 (second mounting portion). On the other hand, the sound hole 123a (second sound hole) is disposed on the other side (D2 direction side) of the space partitioned by the virtual plane P51. Here, the opening area of the sound hole 123a (second sound hole) provided in the shielding region AR51 where the acoustic signal AC1 (first acoustic signal) is blocked by the support portion 2121b of the mounting portion 2121 (first mounting portion) or the support portion 2122b of the mounting portion 2122 (second mounting portion) or in the vicinity thereof is reduced. That is, as illustrated in FIG. 40B, it is assumed that the sound hole 123a (second sound hole) is provided along the aforementioned circumference C1. Also, assume a case where the surface of the wall portion 123 of the housing 12 is equally divided into a plurality of unit area regions (in this example, unit area regions C5-1, C5-2, C5-3, C5-4) along the circumference C1.In this example, the number of sound holes 123a (second sound holes) provided in any of the first unit area regions (in this example, unit area regions C5-2 and C5-3), which are any of the unit area regions including the shielding region AR51, is smaller than the number of sound holes 123a (second sound holes) provided in any of the second unit area regions (in this example, unit area regions C5-1 and C5-4), which are unit area regions not including the shielding region AR51. In this case, the total opening area of the sound holes 123a (second sound holes) provided in any of the first unit area regions (in this example, unit area regions C5-2 and C5-3), which are any of the unit area regions including the shielding region AR51, is smaller than the total opening area of the sound holes 123a (second sound holes) provided in any of the second unit area regions (in this example, unit area regions C5-1 and C5-4), which are unit area regions not including the shielding region AR51. Thereby, sound leakage can be effectively suppressed.

[0124] As illustrated in FIGS. 41A and 41B, the number of sound holes 123a (second sound holes) provided in the first unit area region (in this example, unit area regions C5-2 and C5-3) including the shielding region AR51 is smaller than the number of sound holes 123a (second sound holes) provided in the second unit area region (in this example, unit area regions C5-1 and C5-4) not including the shielding region AR51. Further, sound holes 123a having a larger opening area than the first unit area region may be provided in the second unit area region. In addition, the number of sound holes 123a may be equal in the first unit area region and the second unit area region, and the opening area of each sound hole 123a provided in the first unit area region may be smaller than the opening area of each sound hole 123a provided in the second unit area region. Also in such a case, the total opening area of the sound holes 123a (second sound holes) provided in the first unit area region (in this example, unit area regions C5-2 and C5-3) is smaller than the total opening area of the sound holes 123a (second sound holes) provided in the second unit area region (in this example, unit area regions C5-1 and C5-4). Even in this way, sound leakage can be effectively suppressed.

[0125] <Wearing method 8> The wearing method 8 is exemplified using FIGS. 42, 43A, and 43B. As illustrated in FIGS. 42 and 43A, the acoustic signal output device 2500 of the wearing method 8 includes a housing 2112 that emits an acoustic signal, and a wearing part 2221 that holds the housing 2112 and is configured to be worn on the auricle 1020.

[0126] The wearing part 2221 includes a fixing part 2221a having a concave inner wall surface 2221aa configured to be fitted into the upper part 1022 of the auricle 1020, and a shielding wall 2221b configured to cover only a part of the auricle 1020 when the inner wall surface 2221aa side of the fixing part 2221a is fitted into the upper part 1022 of the auricle 1020. The fixing part 2221a in this example has a hollow structure that houses at least a part (for example, the helix 1022a) of the upper part 1022 of the auricle 1020. Considering the burden on the auricle 1020, it is desirable that the inner wall surface 2221aa of the fixing part 2221a is a curved surface. However, this does not limit the present invention. The shielding wall 2221b is a plate having a flat or curved wall surface. The shielding wall 2221b in this example is configured in a shape that covers the upper part 1022 of the auricle 1020 and opens the lower part 1024 of the auricle 1020 to the outside when the inner wall surface 2221aa side of the fixing part 2221a is fitted into the upper part 1022 of the auricle 1020. That is, the end part 2221c (the end part on the side opposite to the fixing part 2221a) side of the shielding wall 2221b is the opening part O51. The opening part O51 is provided at a position that opens the lower part 1024 of the auricle 1020 to the outside when the upper part 1022 of the auricle 1020 is fitted into the inner wall surface 2221aa side of the fixing part 2221a. There is no limitation on the material constituting the wearing part 2221.

[0127] The housing 2112 in this example may be any of the housings 12, 12”, 22 illustrated in the first to fourth embodiments and their modified examples, or may be the housing of an acoustic signal output device that emits acoustic signals such as conventional earphones. The housing 2112 is held on the inner wall surface 2221bb side of the shielding wall 2221b, and the sound hole 2112a that emits the acoustic signal opens in a direction opposite to the inner wall surface 2221bb. When the acoustic signal output device 2500 is attached to the auricle 1020, the outer wall surface 2221ba side of the shielding wall 2221b faces outward, the inner wall surface 2221bb side of the shielding wall 2221b faces the inner side (auricle 1020 side), the sound hole 2112a of the housing 2112 held on the inner wall surface 2221bb is directed toward the external auditory canal 1021, and the housing 2112 is arranged so as not to block the external auditory canal 1021. At this time, since the sound hole 2112a is arranged on the inner side of the shielding wall 2221b, the influence of external noise can be suppressed, and sound leakage of the acoustic signal emitted from the sound hole 2112a can also be suppressed. Furthermore, since the shielding wall 2221b covers only a part of the auricle 1020 (the lower part 1024 side of the auricle 1020 is not blocked), external sound is not completely blocked, and the user can also hear external sound.

[0128] <Wearing method 9> As illustrated in FIG. 44, the acoustic signal output device 2500' of the wearing method 9 is a modified example of the acoustic signal output device 2500 of the wearing method 8, in which the mounting portion 2221 of the acoustic signal output device 2500 is replaced with the mounting portion 2221'. The mounting portion 2221' is such that the shielding wall 2221b of the mounting portion 2221 is replaced with the shielding wall 2221b'. When the inner wall surface 2221aa side of the fixing portion 2221a is fitted into the upper portion 1022 of the auricle 1020, the shielding wall 2221b' is configured in a shape in which a part of the upper portion 1022 of the auricle 1020 is further opened to the outside. That is, the end portion 2221c (the end portion on the side opposite to the fixing portion 2221a) side of the shielding wall 2221b' is the opening portion O51, and a part of the fixing portion 2221a side of the shielding wall 2221b' is also the opening portion O52 (through hole). The opening portion O52 is provided at a position that opens a part of the upper portion 1022 of the auricle 1020 to the outside. Otherwise, it is the same as the wearing method 8. Since the shielding wall 2221b covers only a part of the auricle 1020 (a part of the lower portion 1024 side and the upper portion 1022 side of the auricle 1020 is not blocked), external sounds are not completely blocked, and the user can also hear external sounds.

[0129] <Wearing method 10> When the housing 2112 is the housing 12, 12", 22 illustrated in the first to fourth embodiments and their modified examples, it is desirable that the sound holes 121a, 221a (first sound holes) of the housing 12, 12", 22 are arranged on the inner side of the shielding wall 2221b, and the sound holes 123a, 223a (second sound holes) are arranged on the outer side of the shielding wall 2221b. Thereby, while suppressing the acoustic signal AC1 from being canceled by the acoustic signal AC2 inside the shielding wall 2221b, a part of the acoustic signal AC1 (first acoustic signal) leaking to the outside of the shielding wall 2221b can be canceled by a part of the acoustic signal AC2 emitted from the sound holes 123a, 223a (second sound holes). As a result, the sound leakage of the acoustic signal AC1 to the outside can be effectively suppressed without significantly reducing the listening efficiency of the acoustic signal AC1 by the user.

[0130] Also, in this case, the sound pressure of the acoustic signal AC1 leaking to the outside from the openings O51 and O52 of the shielding walls 2221b and 2221b' is greater than the sound pressure of the acoustic signal AC1 leaking to the outside from the shielding walls 2221b and 2221b' other than the openings O51 and O52. Therefore, it is desirable that the opening area per unit area of the sound holes 123a and 223a (second sound holes) arranged on the side where the openings O51 and O52 are provided is larger than the opening area per unit area of the sound holes 123a and 223a (second sound holes) arranged on the side where the openings O51 and O52 are not provided. Thereby, the distribution of the sound pressure of the acoustic signal AC2 (second acoustic signal) emitted from the sound holes 123a and 223a (second sound holes) can be made closer to the distribution of the sound pressure of the acoustic signal AC1 leaking to the outside of the shielding wall 2221b, and the acoustic signal AC1 can be appropriately canceled by the acoustic signal AC2. That is, the acoustic signal AC1 (first acoustic signal) is emitted from the sound holes 121a and 221a (first sound holes), and the acoustic signal AC2 (second acoustic signal) is emitted from the sound holes 123a and 223a (second sound holes). The attenuation rate η of the acoustic signal AC1 (first acoustic signal) at the position P2 (second point) with respect to the position P1 (first point) in this case 11 is smaller than the attenuation rate η due to the air propagation of the acoustic signal at the position P2 (second point) with respect to the position P1 (first point) 21 by a predetermined value η th as follows, and the balance of the sound pressure distribution can be achieved. Or, the attenuation amount η of the acoustic signal AC1 (first acoustic signal) at the position P2 (second point) with respect to the position P1 (first point) in this case 12 is larger than the attenuation amount η due to the air propagation of the acoustic signal at the position P2 (second point) with respect to the position P1 (first point) 22 by a predetermined value ω th as above, and the balance of the sound pressure distribution can be achieved. Here, the position P1 (first point) is a predetermined point where the acoustic signal AC1 (first acoustic signal) emitted from the sound hole 221a (first sound hole) arrives. Also, the position P2 (second point) here is a predetermined point where the distance from the acoustic signal output device is farther than the position P1 (first point). Thereby, sound leakage can be effectively suppressed.

[0131] Hereinafter, an example will be described in which the housing 2112 is the housing 12 of the first embodiment or a modified example thereof, and this housing 12 (housing 2112) is held by the mounting portion 2221 of the mounting method 8. However, this does not limit the present invention. The housing 2112 may be the housings 12, 12”, 22 exemplified in the second to fourth embodiments and their modified examples, or the housings 12, 12”, 22 may be held by the mounting portion 2221’ of the mounting method 9. Even in this case, the following configuration can be applied.

[0132] As illustrated in FIG. 46B, in this case, the acoustic signal output device 2600 has a driver unit 11 that emits an acoustic signal AC1 (first acoustic signal) to one side (the D1 direction side) and an acoustic signal AC2 (second acoustic signal) that is an inverted phase signal of the acoustic signal AC1 (first acoustic signal) or an approximate signal of the inverted phase signal to the other side (the D2 direction side). As described above, on the wall portions 121, 123 of the housing 12, there are provided one or more sound holes 121a (first sound holes) for guiding the acoustic signal AC1 (first acoustic signal) emitted from the driver unit 11 to the outside, and one or more sound holes 123a (second sound holes) for guiding the acoustic signal AC2 (second acoustic signal) emitted from the driver unit 11 to the outside (FIGS. 46B and 46C). As described above, a part of the acoustic signal AC2 (second acoustic signal) emitted from the sound hole 123a (second sound hole) cancels a part of the acoustic signal AC1 (first acoustic signal) emitted from the sound hole 121a (first sound hole), thereby suppressing sound leakage. As illustrated in FIG. 46B, the sound hole 121a (first sound hole) of the housing 12 is disposed on the inner side (the D1 direction side) of the shielding wall 2221b, and the sound hole 123a (second sound hole) is disposed on the outer side (the D2 direction side) of the shielding wall 2221b. Thereby, while suppressing the acoustic signal AC1 from being canceled by the acoustic signal AC2 on the inner side of the shielding wall 2221b, a part of the acoustic signal AC1 (first acoustic signal) leaking to the outer side of the shielding wall 2221b can be canceled by a part of the acoustic signal AC2 emitted from the sound hole 123a (second sound hole). As a result, the sound leakage of the acoustic signal AC1 to the outside can be effectively suppressed without significantly reducing the listening efficiency of the acoustic signal AC1 by the user.

[0133] As described above, a part of the shielding wall 2221b (on the side of the end portion 2221c) is provided with an opening portion O51 that partially opens to the outside a portion (lower portion 1024) of the auricle 1020 when the upper portion 1022 of the auricle 1020 is fitted into the inner wall surface 2221aa side of the fixing portion 2221a (FIGS. 46A and 46B). That is, the opening portion O51 in this example is provided at a position that opens the lower portion 1024 of the auricle 1020 to the outside when the upper portion 1022 of the auricle 1020 is fitted into the inner wall surface 2221aa side of the fixing portion 2221a. Here, the opening area per unit area (FIG. 46B) of the sound hole 123a (second sound hole) arranged on the side where the opening portion O51 is provided is larger than the opening area per unit area (FIG. 46C) of the sound hole 123a (second sound hole) arranged on the side where the opening portion is not provided. That is, as illustrated in FIGS. 46B, 46C, and 47A, the sound hole 123a (second sound hole) is provided along the above-described circumference C1. Here, assume a case where the surface of the wall portion 123 of the housing 12 is equally divided into unit area regions (in this example, unit area regions C5-1 and C5-2) along the circumference C1. In this example, the number of the sound holes 123a (second sound holes) arranged on the side where the opening portion O51 is provided (unit area region C5-1) is larger than the number of the sound holes 123a (second sound holes) arranged on the side where the opening portion is not provided (unit area region C5-2). Therefore, the opening area per unit area arranged on the side where the opening portion O51 is provided (unit area region C5-1) is larger than the opening area per unit area of the sound hole 123a (second sound hole) arranged on the side where the opening portion is not provided (unit area region C5-2). Thereby, the distribution of the sound pressure of the acoustic signal AC2 (second acoustic signal) emitted from the sound holes 123a and 223a (second sound holes) can be made closer to the distribution of the sound pressure of the acoustic signal AC1 leaking to the outside of the shielding wall 2221b, and the acoustic signal AC1 can be appropriately canceled by the acoustic signal AC2, and sound leakage can be effectively suppressed.

[0134] Alternatively, as illustrated in FIG. 47B, the average value of the opening areas of the sound holes 123a (second sound holes) arranged on the side where the opening portion O51 is provided (unit area region C5-1) may be larger than the average value of the opening areas of the sound holes 123a (second sound holes) arranged on the side where the opening portion is not provided (unit area region C5-2). Or, as illustrated in FIG. 48A, on the side where the opening portion O51 is provided (unit area region C5-1), two sound holes 123a (second sound holes) arranged side by side in a direction orthogonal to the circumference C1 may be arranged at equal intervals in the direction of the circumference C1, and on the side where the opening portion is not provided (unit area region C5-2), the sound holes 123a (second sound holes) may be arranged at equal intervals in the direction of the circumference C1 one by one. Or, as illustrated in FIG. 48B, the sound holes 123a (second sound holes) may be arranged on the side where the opening portion O51 is provided (unit area region C5-1), but the sound holes 123a (second sound holes) may not be arranged on the side where the opening portion is not provided (unit area region C5-2). Even in this way, sound leakage can be effectively suppressed.

[0135] [Sixth Embodiment] In the sixth embodiment, other wearing methods of the ear-mounted acoustic signal output device will be exemplified.

[0136] <Wearing Method 11> As in the acoustic signal output device 3100 illustrated in FIG. 49A, the mounting portion 2121 of the acoustic signal output device 2100 of the mounting method 1 may be omitted.

[0137] <Wearing Method 12> As in the acoustic signal output device 3200 illustrated in FIG. 49B, the mounting portion 2123 of the acoustic signal output device 2100 of the mounting method 1 may be omitted, and the housing 2112 may be any of the housings 12, 12”, 22 described above. However, in this example, when the acoustic signal output device 3200 is mounted on the auricle 1020, the opening direction (D1) direction of the sound holes 121a, 221a of the housings 12, 12”, 22 is configured to be substantially perpendicular to the direction of the external auditory canal 1021.

[0138] <Wearing Method 13> Similar to the acoustic signal output device 3300 illustrated in FIG. 50A, the mounting portion 2121 of the acoustic signal output device 2300 of mounting method 5 may be omitted, and the housing 2112 may be any of the aforementioned housings 12, 12”, 22. In this example, when the acoustic signal output device 3300 is mounted on the auricle 1020, the sound holes 121a, 221a of the housing 12, 12”, 22 are configured to face the external auditory canal 1021 side.

[0139] <Mounting method 14> Similar to the acoustic signal output device 3600 illustrated in FIG. 50B, the mounting portion 2221 of the acoustic signal output device 2500 of mounting method 8 may be replaced with a mounting portion 2221’. The mounting portion 2221’ includes a shielding wall 2221b configured to cover only the upper portion 1022 of the auricle 1020 when the inner wall surface side of the fixing portion 2221a is fitted into the upper portion 1022 of the auricle 1020. Further, the end portion 2221c’ of the shielding wall 2221b is configured in a curved shape, and the area covered by the shielding wall 2221b on the helix 1022a side of the auricle 1020 is smaller than the area covered by the shielding wall 2221b on the root side of the auricle 1020.

[0140] <Mounting method 15> Similar to the acoustic signal output device 4100 illustrated in FIG. 51A, the mounting portion 2122 of the acoustic signal output device 2200 of mounting method 4 may be omitted.

[0141] <Mounting method 16> Similar to the acoustic signal output device 4100’ illustrated in FIG. 51B, the mounting portion 2122 of the acoustic signal output device 2200 of mounting method 4 may be omitted, and a mounting portion 4421 configured to contact the concha cavity 1025 of the auricle 1020 during mounting may be provided. One end of the mounting portion 4421 holds the housing 2112, and the other end of the mounting portion 4421 is configured in a shape that can support the concha cavity 1025 so as not to block the external auditory canal. Thereby, more stable mounting becomes possible.

[0142] <Mounting method 17> The acoustic signal output device 4200 illustrated in FIG. 52A includes a housing 2112, a columnar mounting portion 4210 that holds the housing 2112 and is configured to be disposed on the root side of the auricle 1020 during wearing, and an arc-shaped mounting portion 4220 that is held at both ends of the mounting portion 4210 and is mounted in the region from the back side to the lower side portion 1024 of the upper side portion 1022 of the auricle 1020.

[0143] <Wearing method 18> As in the acoustic signal output device 4300 illustrated in FIG. 52B, the mounting portion 2122 of the acoustic signal output device 2200 of wearing method 4 may be omitted, and the housing 2112 may be any of the aforementioned housings 12, 12”, 22. However, in this example, when the acoustic signal output device 4300 is mounted on the auricle 1020, the opening direction (D1) of the sound holes 121a, 221a of the housings 12, 12”, 22 is configured to be substantially perpendicular to the direction of the external auditory canal 1021.

[0144] <Wearing method 19> The acoustic signal output device 5110 of wearing method 19 illustrated in FIGS. 53A to 53E includes a housing 5111 that emits an acoustic signal, and a mounting portion 5112 that holds the housing 5111 and is of a type that is hooked on the back side of the upper side portion 1022 of the auricle 1020 during wearing. The mounting portion 5112 is a bent rod-shaped member, and the housing 5111 is rotatably attached to one end thereof in the R5 direction. As illustrated in FIG. 53E, the housing 5111 is mounted in a state where the sound hole from which the acoustic signal is emitted faces the external auditory canal side without blocking the external auditory canal. At this time, the auricle 1020 is sandwiched between the housing 5111 and the mounting portion 5112, whereby the acoustic signal output device 5110 is fixed to the auricle 1020. Further, since the housing 5111 is rotatable in the R5 direction with respect to one end of the mounting portion 5112, the mounting position and the position of the sound hole can be adjusted according to the size and shape of each auricle 1020.

[0145] <Wearing method 20> The acoustic signal output devices 5120 of the wearing method 20 illustrated in FIGS. 54A to 54C include a housing 5121 that emits an acoustic signal, and a wearing part 5122 that holds the housing 5121 and is of a type that is hooked on the back side of the upper part 1022 of the auricle 1020 during wearing. Different from the wearing method 19, the housing 5121 is not rotatable with respect to the wearing part 5122. As illustrated in FIG. 54C, the housing 5121 is worn with the sound hole from which the acoustic signal is emitted facing the external auditory canal without closing the external auditory canal. At this time, the auricle 1020 is sandwiched between the housing 5121 and the wearing part 5122, whereby the acoustic signal output device 5120 is fixed to the auricle 1020.

[0146] <Wearing method 21> The acoustic signal output devices 5130 and 5140 of the wearing method 21 illustrated in FIGS. 55A and 55B each include a housing 5131 and 5141 that emits an acoustic signal, and a wearing part 5132 and 5142 that holds the housing 5131 and 5141 and is of a type that is hooked on the back side of the upper part 1022 of the auricle 1020 during wearing. Further, the acoustic signal output device 5140 illustrated in FIG. 55B is provided with a wearing part 5143 configured to contact the concha cavity 1025 of the auricle 1020 during wearing. Thereby, more stable wearing becomes possible.

[0147] <Wearing method 22> The acoustic signal output device 5150 illustrated in FIGS. 56A, 56B, and 56C includes a housing 5151 that emits an acoustic signal, a rod-shaped mounting portion 5152 that holds the housing 5151 and is of a type that is hooked on the back side of the upper portion 1022 of the auricle 1020 when worn, a columnar support portion 5154 that holds the housing 5151 at one end and the mounting portion 5152 at the other end, a rod-shaped mounting portion 5153 that is of a type that is hooked on the back side of the middle portion 1023 and the upper portion 1022 of the auricle 1020 from the middle portion 1023 side when worn, and a columnar support portion 5155 that holds the housing 5151 at one end and the mounting portion 5153 at the other end. As illustrated in FIG. 56C, the housing 5151 is worn in a state where a sound hole through which the acoustic signal is emitted faces the external auditory canal without blocking the external auditory canal. At this time, the auricle 1020 is sandwiched between the housing 5151 and the mounting portions 5152 and 5153, whereby the acoustic signal output device 5150 is fixed to the auricle 1020.

[0148] <Wearing method 23> The acoustic signal output device 5160 illustrated in FIGS. 57A to 57E includes a housing 5161 that emits an acoustic signal, a columnar mounting portion 5164 that holds the housing 5161 and is configured to be disposed on the root side of the auricle 1020 when worn, a rod-shaped mounting portion 5162 that is held at one end of the mounting portion 5164 and is of a type that is hooked on the back side of the upper portion 1022 of the auricle 1020 when worn, and a rod-shaped mounting portion 5163 that is held at the other end of the mounting portion 5164 and is of a type that is hooked on the back side of the lower portion 1024 of the auricle 1020 when worn. As illustrated in FIG. 57E, the housing 5161 is worn in a state where a sound hole through which the acoustic signal is emitted faces the external auditory canal without blocking the external auditory canal. At this time, the auricle 1020 is sandwiched between the housing 5161 and the mounting portion 5164 and the mounting portions 5162 and 5163, whereby the acoustic signal output device 5160 is fixed to the auricle 1020.

[0149] <Wearing method 24> The acoustic signal output devices 5170 and 5180 illustrated in FIGS. 58A to 58D and FIGS. 59A to 59D each include a housing 5171, 5181 that emits an acoustic signal, columnar mounting portions 5172, 5182 configured to be disposed on the back side of the middle portion 1023 of the auricle 1020 when worn, and curved belt-shaped support portions 5173, 5183 having one end holding the housing 5171, 5181 and the other end holding the mounting portions 5172, 5182. As illustrated in FIGS. 58D and 59D, the housings 5171, 5181 are worn with the sound holes through which the acoustic signals are emitted facing the external auditory canal without blocking the external auditory canal. At this time, the auricle 1020 is sandwiched between the housing 5171, 5181 and the mounting portions 5172, 5182, whereby the acoustic signal output devices 5170, 5180 are fixed to the auricle 1020.

[0150] <Wearing method 25> The acoustic signal output device 5190 illustrated in FIGS. 60A to 60C includes a housing 5191 that emits an acoustic signal, and a rod-shaped mounting portion 5192 that holds the housing 5191 and is configured to be disposed on the back side of the auricle 1020 when worn. The mounting portion 5192 holds the housing 5191 at one end on the side disposed on the lower portion 1024 side of the auricle 1020 when worn. As illustrated in FIG. 60C, the housing 5191 is worn with the sound holes through which the acoustic signals are emitted facing the external auditory canal without blocking the external auditory canal. At this time, the auricle 1020 is sandwiched between the housing 5191 and the mounting portion 5192, whereby the acoustic signal output device 5190 is fixed to the auricle 1020.

[0151] <Wearing method 26> The acoustic signal output device 5200 illustrated in FIGS. 61A to 61E has a housing 5201 that emits an acoustic signal and an annular mounting portion 5202 that holds the housing 5021. As illustrated in FIG. 61E, the housing 5201 is mounted in a state where a sound hole through which the acoustic signal is emitted faces the external auditory canal without closing the external auditory canal. When mounted, the auricle 1020 is inserted into the annular mounting portion 5202, and the mounting portion 5202 is disposed on the back side of the upper portion 1022, the middle portion 1023, and the lower portion 1024 of the auricle 1020. At this time, the auricle 1020 is sandwiched between the housing 5201 and the mounting portion 5202, whereby the acoustic signal output device 5200 is fixed to the auricle 1020.

[0152] <Wearing method 27> As illustrated in FIGS. 62A and 64B, an acoustic signal output device of a type in which any one of the housings 12, 12”, 22 illustrated in the first to fourth embodiments and their modified examples is fixed to a temple of glasses may be used.

[0153] In the acoustic signal output devices 5310 and 5320 illustrated in FIGS. 62A and 62B, one end of a support portion 5312 is held at a middle portion of a temple 5311 of glasses, and the other end of the support portion 5312 holds the housing 12. In each of the acoustic signal output devices 5310 and 5320, the temple 5311 of the glasses is disposed on the back side of the upper portion 1022 of the auricle 1020 when mounted. However, in the acoustic signal output device 5310 illustrated in FIG. 62A, the opening direction of the sound hole 121a of the housing 12 is inclined with respect to the external auditory canal 1021 when mounted. On the other hand, in the example of the acoustic signal output device 5320 illustrated in FIG. 62B, the sound hole 121a of the housing 12 is disposed facing the external auditory canal 1021 side when mounted.

[0154] In the acoustic signal output devices 5340 and 5350 illustrated in FIGS. 63A and 63B, the housing 12 is directly held at the middle portion of the temple 5311 of the glasses. In any of the acoustic signal output devices 5340 and 5350, when worn, the temple 5311 of the glasses is disposed on the back side of the upper portion 1022 of the auricle 1020. However, in the acoustic signal output device 5340 illustrated in FIG. 63A, the housing 12 is held by the temple 5311 such that the opening direction of the sound hole 121a of the housing 12 is substantially perpendicular to the temple 5311, and when worn, the opening direction of the sound hole 121a of the housing 12 is arranged to be substantially perpendicular to the external auditory canal 1021. On the other hand, in the acoustic signal output device 5350 illustrated in FIG. 63B, the housing 12 is held by the temple 5311 such that the opening direction of the sound hole 121a of the housing 12 is substantially parallel to the temple 5311, and when worn, the opening direction of the sound hole 121a of the housing 12 is arranged to face the upper portion 1022 of the auricle 1020.

[0155] The acoustic signal output devices 5360 and 5370 illustrated in FIGS. 64A and 64B directly hold the housing 12 at the tip portions of the temples 5361 and 5371 of the glasses. In any of the acoustic signal output devices 5360 and 5370, when worn, the temple 5361 of the glasses is disposed on the back side of the upper portion 1022 of the auricle 1020. However, in the acoustic signal output device 5360 illustrated in FIG. 64A, when worn, the opening direction of the sound hole 121a of the housing 12 is arranged to be directed from the root side of the lower portion 1024 of the auricle 1020 toward the external auditory canal 1021 side. In the acoustic signal output device 5370 illustrated in FIG. 64B, when worn, the opening direction of the sound hole 121a of the housing 12 is arranged to be directed from the outside of the lower portion 1024 of the auricle 1020 toward the external auditory canal 1021 side.

[0156] <Wearing method 28> Alternatively, any of the housings 12, 12”, 22 exemplified in the first to fourth embodiments and their modifications may be fixed to a rod-shaped mounting portion 5381 curved in a shape to be worn on the neck or shoulders of the user 1000, such as the acoustic signal output device 5380 exemplified in FIG. 65A. Also, any of the housings 12, 12”, 22 may be fixed to a rod-shaped mounting portion 5391 curved in a shape to be worn on the top of the head of the user 1000, such as the acoustic signal output device 5390 exemplified in FIG. 65B. Further, any of the housings 12, 12”, 22 may be fixed to a rod-shaped mounting portion 5401 curved in a shape to be worn on the back of the head and the auricle 1020 of the user 1000, such as the acoustic signal output device 5400 exemplified in FIG. 65C.

[0157] <Other mounting methods> Alternatively, the mounting method of an existing open-ear type earphone may be applied to the acoustic signal output devices 4, 4’, 10, 20, 30 exemplified in the first to fourth embodiments and their modifications. For example, as exemplified in Reference 1 (https: / / www.sony.jp / headphone / products / STH40D / feature_1.html), an annular body serving as a stopper may be added to the D1 direction side of the housing 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2, and a U-shaped mounting portion may be added to the side opposite to the D1 direction of the housing 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2. In this case, the annular body is applied to the peripheral portion of the outer ear canal (for example, the concha), and the lower portion of the auricle is sandwiched by the U-shaped mounting portion, whereby the housing 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 is mounted on the auricle. In particular, when applying the mounting method of Reference 1 to the acoustic signal output device 20 of the second embodiment, an annular body serving as a stopper may be added to the D1 direction side of the housing 22, and the U-shaped mounting portion added to the D2 direction side of the housing 22 may be configured to also serve as the waveguide tubes 24, 25 and the housing 23 (FIG. 20).

[0158] For example, as illustrated in Reference 2 (https: / / www.bose.com / en_us / products / headphones / earbuds / sport-open-earbuds.html#v=sport_open_earbuds_black), the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 may be substantially elliptical columnar, and a J-shaped mounting portion may be provided on the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2. In this case, by applying the D1 direction side of the housing 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 to the front side (outer ear canal side) of the upper portion of the auricle and hooking the J-shaped mounting portion to the back side of the upper portion of the auricle, the housing 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 are mounted on the auricle.

[0159] For example, as illustrated in Reference 3 (https: / / ambie.co.jp / soundearcuffs / tws / ), the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 are configured to be substantially spherical, and the side opposite to the D1 direction of the housing 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 may be held at one end side of a C-shaped mounting portion. The other end of this C-shaped mounting portion may also be configured to be substantially spherical. In this case, by applying the D1 direction side of the housing 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 to the peripheral portion (e.g., concha) of the outer ear canal and gripping (pinching) the middle portion of the auricle with the C-shaped mounting portion, the housing 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 are mounted on the auricle.

[0160] For example, as illustrated in Reference 4 (https: / / www.jabra.jp / bluetooth-headsets / jabra-elite-active-45e##100-99040000-40), sound ducts for directing the acoustic signals emitted from the sound holes 121a, 221a to the outer ear canal may be added to the sound holes 121a, 221a of the housing 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2.

[0161] For example, as illustrated in Reference 5 (https: / / www.audio-technica.co.jp / product / ATH-EW9), a semi-circular mounting portion (ear hook) provided with an adjustment mechanism (slide fit mechanism) for adjusting the position of the mounted housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 with respect to the auricle may be provided. In this case, by applying the D1 direction side of the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 to the front side of the upper portion of the auricle and hooking the semi-circular mounting portion on the back side of the upper portion of the auricle, the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 are mounted on the auricle. By operating the adjustment mechanism in this state, the position of the mounted housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 with respect to the auricle can be adjusted.

[0162] For example, as illustrated in Reference 6 (https: / / www.mu6.live / ), a headband-type mounting portion may be provided on the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2. For example, both ends of the headband-type mounting portion may hold the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2. At this time, the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 may be rotatable with respect to both ends of the headband-type mounting portion. In this case, by applying the D1 direction side of the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 to the auricle or the vicinity of the auricle and mounting the headband-type mounting portion on the head. At this time, by rotating the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 with respect to the headband-type mounting portion, the mounting position of the headband-type mounting portion and the position of the housings 12, 12”, 22 or the acoustic signal output portions 40-1, 40-2 with respect to the auricle can be adjusted.

[0163] [Other modification examples, etc.] Note that the present invention is not limited to the above-described embodiments. For example, in each of the above-described embodiments and their modifications, examples of applying the present invention to a device for acoustic listening (e.g., an open-ear type earphone, headphone, etc.) that is worn on the ear without sealing the user's external auditory canal have been shown. However, this does not limit the present invention, and the present invention may be applied to a device for acoustic listening that is worn on a body part other than the ear without sealing the user's external auditory canal, such as a bone conduction earphone or a neck speaker earphone.

[0164] In addition, for example, the present invention may be used as an acoustic signal output device capable of controlling the attenuation rate of an acoustic signal emitted to the outside even without providing a sound-absorbing material in a sound hole through which the acoustic signal emitted from the driver unit passes. Also, for example, the present invention may be used as an acoustic signal output device capable of attenuating an acoustic signal emitted from the driver unit so that it cannot be listened to at a predetermined position even without performing directivity control by physical shape or signal processing. Also, for example, the present invention may be used as an acoustic signal output device capable of attenuating an acoustic signal at a location even without arranging a speaker at the location where the acoustic signal is to be attenuated. Also, for example, the present invention may be used as an acoustic signal output device capable of locally reproducing an acoustic signal in a specific local area even without covering the periphery of the specific local area with a sound-absorbing material.

Description of Reference Numerals

[0165] 4,4’,10,20,30,2100 - 2600,3100 - 3300,3600,4100 - 4300,5110 - 5200,5310 - 5400 Acoustic signal output device 11 Driver unit 113 Diaphragm 12,12”,22,23,2112,5021,5111,5121,5131,5151,5161,5171,5191,5201 Housing 121a,123a,221a,223a Sound hole 13 Sound-absorbing material 24,25 Waveguide 31,41 Circuit section 40-1 and 40-2 Audio Signal Output Sections AC1 and AC2 Audio Signals AR21 and AR22 Hollow Parts C1 Circumference C1-1, C1-2, C1-3, and C1-4 Unit Arc Areas MAC1 and MAC2 Monoral Audio Signals Mounting Parts: 2121, 2122, 2123, 2124, 2221, 2224, 4210, 4220, 4421, 5112, 5122, 5132, 5152, 5153, 5162, 5163, 5164, 5172, 5192, 5202, 5381, 5391, 5401 Fixing Parts: 2121a, 2122a, 2123a, 2124a, 2221a 2221b Shielding Wall

Claims

1. An acoustic signal output device having at least two driver units, a first driver unit that emits a first acoustic signal to one side and a second acoustic signal to the other side, a second driver unit that emits a fourth acoustic signal to one side and a third acoustic signal to the other side, a housing portion provided with a sound hole for guiding externally the acoustic signal emitted from one side of the driver unit and a sound hole for guiding externally the acoustic signal emitted from the other side of the driver unit, and having the frequency bandwidths of the third acoustic signal and the fourth acoustic signal emitted from the second driver unit are narrower than the frequency bandwidths of the first acoustic signal and the second acoustic signal emitted from the first driver unit, the second acoustic signal is a signal having a substantially opposite phase to the first acoustic signal, the fourth acoustic signal is a signal having a substantially opposite phase to the third acoustic signal, an acoustic signal output device.

2. The acoustic signal output device according to Claim 1, the attenuation rate of the first acoustic signal at a second point farther from the acoustic signal output device than the first point based on the predetermined first point to which the first acoustic signal reaches is designed to be equal to or less than a predetermined value smaller than the attenuation rate due to air propagation of the acoustic signal at the second point based on the first point, or the attenuation amount of the first acoustic signal at the second point based on the first point is designed to be equal to or greater than a predetermined value larger than the attenuation amount due to air propagation of the acoustic signal at the second point based on the first point, an acoustic signal output device.

3. The acoustic signal output device according to Claim 2, the magnitudes of the components of the third acoustic signal and the fourth acoustic signal having a frequency of a first frequency or higher emitted from the second driver unit are smaller than the magnitudes of the components of the first acoustic signal and the second acoustic signal having a frequency of the first frequency or higher emitted from the first driver unit, an acoustic signal output device.

4. The acoustic signal output device according to any one of Claims 1 to 3, the magnitudes of the components of the third acoustic signal and the fourth acoustic signal having a frequency of a second frequency or lower emitted from the second driver unit are smaller than the magnitudes of the components of the first acoustic signal and the second acoustic signal having a frequency of the second frequency or lower emitted from the first driver unit, an acoustic signal output device.

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