Speaker device

Abstract

The speaker device (1) includes a signal processing circuit that performs signal processing on an input first audio signal to generate a first output signal and a second output signal, a first speaker (10) that outputs a first sound (S1) based on the first output signal in a first direction, a first horn (15) that emits the first sound (S1) output from the first speaker (10) in the first direction, and a second speaker (20) that is disposed on the second direction side of the first speaker (10) that is opposite to the first direction and outputs a second sound (S2) based on the second output signal. The signal processing circuit has a first filter and a second filter. The first filter and the second filter have filter characteristics that adjust the phase and amplitude of the input signal for each frequency so that the sound pressure of the sound based on the first audio signal at the second position is lower than the sound pressure of the sound based on the first audio signal at the first position by a predetermined value or more.

Description

[Technical field]

[0001] The present disclosure relates to a speaker device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, directional speakers are known that radiate sound in a specific direction and suppress the sound pressure of the sound in positions in directions other than the specific direction.

[0003] For example, Patent Document 1 discloses a technology that achieves sound directionality by using two speakers that emit acoustic signals in opposite phases to each other and delaying the time at which one speaker emits the acoustic signal depending on the distance between the two speakers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-33104 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a speaker device having directionality for sounds in a wide frequency range. [Means for solving the problem]

[0006] A speaker device according to one aspect of the present disclosure includes a signal processing circuit that performs signal processing on an input first audio signal to generate a first output signal and a second output signal, a first speaker that outputs a first sound based on the first output signal in a first direction, a first horn that emits the first sound output from the first speaker in the first direction, and a second speaker that is disposed on a second direction side of the first speaker that is opposite to the first direction and outputs a second sound based on the second output signal, the signal processing circuit having a first filter and a second filter that perform signal processing on a signal of at least a part of a frequency band of the first audio signal, and the first output signal is output through the first horn. the first output signal is generated based on the output of a filter, the second output signal is generated based on the output of the second filter, the first filter and the second filter have filter characteristics that adjust the phase and amplitude for each frequency of a signal in at least a part of a frequency band of the first audio signal so that the sound pressure of the sound based on the first audio signal at the second position is reduced by a predetermined value or more when the first sound and the second sound overlap, relative to the sound pressure of the sound based on the first audio signal at the first position, the first position is located directly in front of the first speaker in the first direction, and the second position is located in a direction that forms a predetermined angle with respect to the first direction, relative to the first speaker. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a speaker device having directionality for sounds in a wide frequency range. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view showing an example of an external appearance of a speaker device according to an embodiment. [Diagram 2] FIG. 2 is a block diagram illustrating an example of a functional configuration of the speaker device according to the embodiment. [Diagram 3] FIG. 3 is a diagram for explaining a method for designing the filter characteristics of the first FIR filter and the second FIR filter. [Figure 4]FIG. 4 is a flowchart illustrating an example of a method for determining the filter characteristics of the first FIR filter and the second FIR filter. [Diagram 5] FIG. 5 is a diagram for explaining the effect of the speaker device according to the embodiment. [Figure 6] FIG. 6 is a graph showing an example of the directivity of a sound output from a speaker device according to a comparative example. [Figure 7] FIG. 7 is a graph showing an example of the directivity of a sound output from the speaker device according to the embodiment. [Figure 8] FIG. 8 is a plan view showing an example of an external appearance of a speaker device according to the first modification of the embodiment. [Figure 9] FIG. 9 is a plan view showing an example of an external appearance of another speaker device according to the first modification of the embodiment. [Figure 10] FIG. 10 is a block diagram showing an example of a functional configuration of a speaker device according to the second modification of the embodiment. [Figure 11] FIG. 11 is a plan view showing an example of an external appearance of a speaker device according to a third modification of the embodiment. [Figure 12] FIG. 12 is a graph showing an example of the directivity of sound emitted from a speaker device having a configuration in which the sound absorbing material and the sound reflecting material are removed from the speaker device according to the third modification of the embodiment. [Figure 13] FIG. 13 is a graph showing an example of the directivity of a sound output from a speaker device according to the third modification of the embodiment. [Figure 14] FIG. 14 is a plan view showing an example of an external appearance of a first alternative speaker device according to the third modification of the embodiment. [Figure 15] FIG. 15 is a plan view showing an example of an external appearance of a second alternative speaker device according to the third modification of the embodiment. [Figure 16] FIG. 16 is a plan view showing an example of an external appearance of a third alternative speaker device according to the third modification of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Summary of the Disclosure) As an outline of the present disclosure, an example of a speaker device according to the present disclosure will be described below.

[0010] A speaker device according to a first aspect of the present disclosure includes a signal processing circuit that performs signal processing on an input first audio signal to generate a first output signal and a second output signal, a first speaker that outputs a first sound based on the first output signal in a first direction, a first horn that emits the first sound output from the first speaker in the first direction, and a second speaker that is disposed on a second direction side of the first speaker that is opposite to the first direction and outputs a second sound based on the second output signal, the signal processing circuit having a first filter and a second filter that perform signal processing on a signal of at least a part of a frequency band of the first audio signal, and the first output signal is output through the first horn. the first output signal is generated based on the output of a filter, the second output signal is generated based on the output of the second filter, the first filter and the second filter have filter characteristics that adjust the phase and amplitude for each frequency of a signal in at least a part of a frequency band of the first audio signal so that the sound pressure of the sound based on the first audio signal at the second position is reduced by a predetermined value or more when the first sound and the second sound overlap, relative to the sound pressure of the sound based on the first audio signal at the first position, the first position is located directly in front of the first speaker in the first direction, and the second position is located in a direction that forms a predetermined angle with respect to the first direction, relative to the first speaker.

[0011] This makes it possible to realize a speaker device having directivity for sounds in a wide frequency range. Specifically, the first horn improves the linearity of the first sound, so that the directivity of the sound emitted by the speaker device can be improved. This improvement in directivity is particularly effective for high-pitched sounds that have a high linearity. The first sound and the second sound are based on the output of the first filter and the second filter, and the sound pressure of the sound based on the first audio signal at the second position is reduced by a predetermined value or more compared to the sound pressure of the sound based on the first audio signal at the first position, because the first sound is cancelled out by the second sound. Therefore, it is possible to improve the directivity of sounds in the mid-low range, where interference between the first sound and the second sound is likely to occur. In addition, the phase and amplitude of the first audio signal for each frequency are adjusted by the first filter and the second filter, so that the first sound is cancelled out by the second sound over a wide frequency range, and the amount of cancellation is also large, compared to the case where a sound having an inverse phase to the first sound is simply used as the second sound. Therefore, a speaker device having directivity for sounds in a wide frequency range can be realized.

[0012] Also, for example, a speaker device according to a second aspect of the present disclosure is the speaker device according to the first aspect, wherein the signal processing circuit has a low-pass filter to which the first audio signal is input, and the first filter and the second filter perform signal processing on the output of the low-pass filter.

[0013] This reduces the processing load of the first filter and the second filter.

[0014] Also, for example, a speaker device according to a third aspect of the present disclosure is a speaker device according to the first or second aspect, and includes a cylindrical housing whose axial direction is the first direction, the first speaker is provided at an end of the housing on the first direction side, and a plurality of through holes are formed in a circumferential side wall of the housing.

[0015] As a result, sounds having an opposite phase to the first sound are output from the multiple through-holes, and the first sound is cancelled out by the sounds having an opposite phase to the first sound, thereby further increasing the directionality of the sound emitted by the speaker device.

[0016] Also, for example, a speaker device according to a fourth aspect of the present disclosure is the speaker device according to any one of the first to third aspects, wherein the second speaker outputs the second sound in the second direction.

[0017] This makes it possible to increase the distance between the output position of the first sound from the first speaker and the output position of the second sound from the second speaker while preventing the overall size of the speaker device from increasing, thereby reducing the sound pressure of the sound based on the first audio signal at the second position.

[0018] Also, for example, a speaker device according to a fifth aspect of the present disclosure is the speaker device according to any one of the first to fourth aspects, and further includes a diffuser that diffuses the second sound output from the second speaker.

[0019] This allows the second sound to be diffused, expanding the range over which the second sound can cancel out the first sound.

[0020] Also, for example, a speaker device according to a sixth aspect of the present disclosure is a speaker device according to any one of the first to fifth aspects, and includes a second horn that emits the second sound output from the second speaker in the first direction.

[0021] This allows the second horn to suppress the increase in the path difference between the first sound and the second sound traveling toward the second direction of the speaker device, making it easier for the first sound to be canceled out by the second sound even on the second direction side of the speaker device.

[0022] Also, for example, a speaker device according to a seventh aspect of the present disclosure is a speaker device according to any one of the first to sixth aspects, wherein the signal processing circuit has an adder that generates the second output signal by adding a second audio signal indicating a masking sound to an output of the second filter.

[0023] As a result, the second sound includes a masking sound, so that even if the speaker device is installed in a quiet environment, the sound based on the first audio signal can be made difficult to hear at the second position due to the masking sound.

[0024] Also, for example, a speaker device according to an eighth aspect of the present disclosure is a speaker device according to any one of the first to seventh aspects, and includes a plate-shaped sound-absorbing material arranged to include a portion surrounding the first speaker and the second speaker when viewed from the first direction side, the sound-absorbing material absorbs the first sound and the second sound traveling in the second direction side, and the predetermined angle is an angle between a first angle formed by a direction in which a surface of the sound-absorbing material on the first direction side extends and the first direction in a cross-sectional view on a plane parallel to the first direction passing through the center of the first speaker, and a second angle formed by a direction connecting the sound output position of the first speaker and an end of the surface and the first direction in the cross-sectional view.

[0025] By the sound absorbing material absorbing sound, the sound pressure can be reduced and the directivity can be improved on the second direction side of the speaker device where the first sound is less likely to be cancelled out by the second sound.

[0026] Also, for example, a speaker device according to a ninth aspect of the present disclosure is the speaker device according to the eighth aspect, further comprising a plate-shaped sound reflecting material disposed on the second direction side with respect to the sound absorbing material.

[0027] This allows the components of the first and second sounds incident on the sound-absorbing material that are not absorbed by the sound-absorbing material to be reflected, thereby further reducing the sound pressure on the second direction side of the speaker device and improving directionality.

[0028] Also, for example, a speaker device according to a tenth aspect of the present disclosure is the speaker device according to the eighth or ninth aspect, in which the first angle is 90 degrees.

[0029] This makes it possible to suppress disturbance of the sound pressure characteristics of the sound emitted by the speaker device when part of the sound emitted by the speaker device is reflected by the sound absorbing material.

[0030] Hereinafter, an embodiment will be described with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0031] It should be noted that the inventors of the present application provide the accompanying drawings and the following description so that those skilled in the art can fully understand the present disclosure, and they do not intend to limit the subject matter described in the claims.

[0032] In the following embodiments, for convenience of explanation, the front-rear direction is made to coincide with the X-axis direction, the left-right direction (horizontal direction) is made to coincide with the Y-axis direction, and the up-down direction is made to coincide with the Z-axis direction, but these correspondences do not limit the posture of the speaker device according to the present disclosure during manufacturing or use. In addition, the X-axis, Y-axis, and Z-axis indicate three axes of a three-dimensional orthogonal coordinate system. In the following explanation, for example, the positive X-axis direction indicates the direction of the arrow of the X-axis, and the negative X-axis direction indicates the opposite direction to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. In addition, the positive X-axis direction (forward) is an example of the first direction, and the negative X-axis direction (backward) is an example of the second direction. In addition, each figure is a schematic diagram and is not necessarily illustrated strictly. Therefore, the scales and the like in each figure do not necessarily coincide.

[0033] In addition, in this specification, ordinal numbers such as "first" and "second" do not refer to the number or order of components, unless otherwise specified, but are used for the purpose of avoiding confusion and distinguishing between components of the same type.

[0034] (Embodiment) The speaker device according to the present embodiment will be described below.

[0035] [composition] First, the configuration of a speaker device according to the present embodiment will be described with reference to FIG. 1 and FIG.

[0036] FIG. 1 is a plan view showing an example of the appearance of a speaker device 1 according to the present embodiment. FIG. 2 is a block diagram showing an example of the functional configuration of the speaker device 1 according to the present embodiment. FIG. 1 shows the appearance of the speaker device 1 when viewed from above (Z-axis positive direction side). For the sake of explanation, FIG. 1 shows a cross section of the first horn 15 cut in half along the XY plane, and the remaining half of the first horn 15 is actually located on the front side of the paper in FIG. 1 (Z-axis positive direction side). Also, in FIG. 1, the first speaker 10, the second speaker 20, and the substrate 30 housed in the first housing 11, the second housing 21, and the third housing 31, respectively, are shown by dashed lines. Also, in FIG. 1, the sound output from the first speaker 10 through the first horn 15 is typically shown by a solid line arrow A, the sound output from the multiple through holes 12 is typically shown by a dashed line arrow B, and the sound output from the second speaker 20 is typically shown by a dashed line arrow C.

[0037] 1, the speaker device 1 includes a first speaker 10, a first housing 11 that houses the first speaker 10, a first horn 15, a second speaker 20, a second housing 21 that houses the second speaker 20, a diffuser 23, a substrate 30, and a third housing 31 that houses the substrate 30. In the example shown in FIG 1, the third housing 31, the second housing 21, and the first housing 11 are arranged in this order along the positive direction of the X-axis.

[0038] The speaker device 1 is a small directional speaker, for example, with a length of about 40 cm in the front-rear direction and a length of about 20 cm in the left-right direction. The speaker device 1 is configured with two speakers, namely, a first speaker 10 and a second speaker 20, and while having directionality, it is easy to make it small and easy to realize high quality sound. The speaker device 1 is expected to be installed, for example, in a shared space in a house, an office, a commercial facility, etc.

[0039] The speaker device 1, which is a directional speaker, allows people present within a predetermined range on the positive side of the X-axis of the speaker device 1 to hear the sound emitted by the speaker device 1, while making the sound emitted by the speaker device 1 difficult to hear for people present outside the predetermined range. In particular, with a directional speaker, it is important to reduce the sound pressure of a wide frequency range of sound in a location where it is desired to make the sound emitted by the speaker difficult to hear for people (for example, a second position P2 shown in FIG. 3, which will be described later). The speaker device 1 can reduce the sound pressure of a wide frequency range of sound in a desired location.

[0040] The first speaker 10 is provided at the end of the first housing 11 on the positive side of the X-axis, and outputs a first sound S1 in the positive direction of the X-axis. The first sound S1 corresponds to a sound indicated by a first audio signal described later. The first speaker 10 is composed of, for example, a diaphragm, a magnetic circuit, and a voice coil. The first speaker 10 is fixed to the first housing 11 at the end of the first housing 11 on the positive side of the X-axis, with the diaphragm of the first speaker 10 exposed. The diaphragm of the first speaker 10 vibrates in the front-rear direction, and the first sound S1 is output in the positive direction of the X-axis.

[0041] The first housing 11 is a cylindrical housing with the axial direction being the positive direction of the X-axis. The first housing 11 has an internal space for accommodating the first speaker 10, and is also called a speaker cabinet or a speaker box. The outer shape of the first housing 11 is, for example, cylindrical. An opening in which the first speaker 10 is installed is provided at the end of the first housing 11 on the positive direction side of the X-axis, and the opening is blocked by the first speaker 10. In addition, the end of the first housing 11 on the negative direction side of the X-axis is blocked by a plate-shaped member. When viewed from the positive direction side of the X-axis, the center of the first speaker 10 and the center of the first housing 11 coincide with each other.

[0042] A plurality of through holes 12 are formed in the circumferential side wall of the first housing 11, communicating the internal space of the first housing 11 with the outside of the first housing 11. A sound having an opposite phase to the first sound S1 output from the first speaker 10 to the internal space of the first housing 11 is output from the plurality of through holes 12. The arrangement of the through holes 12 is not limited to the example shown in FIG.

[0043] The first horn 15 emits the first sound S1 output from the first speaker 10 in the positive direction of the X-axis. Emitting sound in the positive direction of the X-axis means that the sound is emitted with the positive direction of the X-axis as the center. The first horn 15 is disposed on the positive side of the X-axis with respect to the first speaker 10. When viewed from the positive side of the X-axis, the center of the first speaker 10 and the center of the first horn 15 coincide. The first horn 15 is cylindrical, opens in the positive and negative directions of the X-axis (in other words, the front-to-rear direction), and is attached to the end of the first housing 11 on the positive side of the X-axis so as to surround the space on the positive side of the X-axis of the first speaker 10. The opening on the negative side of the X-axis of the first horn 15 is blocked by the first speaker 10 and the first housing 11, and the opening on the positive side of the X-axis of the first horn 15 is open. The axial direction of the first horn 15 coincides with the positive direction of the X-axis.

[0044] First horn 15 has inner surface 16 which gradually becomes wider in the positive direction of the X-axis. In the example shown in Fig. 1, the angle between the normal to inner surface 16 and the positive direction of the X-axis changes in two steps so that the angle becomes smaller on the positive direction side of the X-axis. The angle between the normal to inner surface 16 and the positive direction of the X-axis may change in three or more steps, may change continuously, or may be constant and not change. The angle between the normal to inner surface 16 and the positive direction of the X-axis (the average angle if it changes) is, for example, larger than a predetermined angle θ described later.

[0045] The second speaker 20 is disposed on the negative X-axis side with respect to the first speaker 10, and outputs the second sound S2 in the negative X-axis direction. The second speaker 20 is provided at the end of the second housing 21 on the negative X-axis side. When viewed from the positive X-axis side, the center of the first speaker 10 and the center of the second speaker 20 coincide with each other. The second sound S2 includes a cancellation sound that can cancel the first sound S1 by being out of phase with the first sound S1. Therefore, at a certain position, the first sound S1 and the second sound S2 overlap, and the sound pressure of the composite sound of the first sound S1 and the second sound S2 at that position decreases. The second speaker 20 is composed of, for example, a diaphragm, a magnetic circuit, a voice coil, and the like. The second speaker 20 is fixed to the second housing 21 at the end of the second housing 21 on the negative X-axis side in a direction in which the diaphragm of the second speaker 20 is exposed. The diaphragm of the second speaker 20 vibrates in the front-rear direction, whereby a second sound S2 is output in the negative direction of the X-axis.

[0046] The second housing 21 is a cylindrical housing with the X-axis positive direction as its axial direction. The second housing 21 is connected to the end of the first housing 11 on the X-axis negative direction side. The first housing 11 and the second housing 21 may be connected via a connecting member. The second housing 21 has an internal space for accommodating the second speaker 20, and is also called a speaker cabinet or a speaker box. The outer shape of the second housing 21 is, for example, cylindrical. An opening in which the second speaker 20 is installed is provided at the end of the second housing 21 on the X-axis negative direction side, and the opening is blocked by the second speaker 20. In addition, the end of the second housing 21 on the X-axis positive direction side is blocked by a plate-shaped member. When viewed from the X-axis positive direction side, the center of the second speaker 20 and the center of the second housing 21 coincide with each other. In addition, no through-hole is formed in the side wall of the second housing 21.

[0047] The diffuser 23 is a member that diffuses the second sound S2 output from the second speaker 20. Since the diffuser 23 diffuses the second sound S2, it is possible to expand the range in which the second sound S2 cancels out the first sound S1. In addition, it is possible to suppress an increase in the sound pressure of the second sound S2 in a specific location.

[0048] The diffuser 23 is disposed on the output direction side of the second speaker 20 from which the second sound S2 is output, that is, on the negative X-axis direction side of the second speaker 20, facing the second speaker 20. The diffuser 23 is fixed to an end of the third housing 31 on the positive X-axis direction side. In the example shown in Fig. 1, the diffuser 23 has a cone-shaped portion that protrudes toward the second speaker 20. Note that the shape of the diffuser 23 is not particularly limited as long as it can diffuse the second sound S2.

[0049] The substrate 30 is a substrate on which a signal processing circuit 50, which will be described later, and the like are formed. The substrate 30 is disposed inside the third housing 31.

[0050] The third housing 31 is a housing that houses the substrate 30. The third housing 31 is disposed on the negative X-axis direction side of the second housing 21 at a distance from the second housing 21, and is connected to the second housing 21 via a connecting member 32. In the example shown in FIG. 1, the shape of the third housing 31 is a truncated pyramid shape, but it may be a cylindrical shape or a rectangular prism shape. Although not shown, a mounting member for mounting the speaker device 1 on a ceiling or the like may be provided on the end of the third housing 31 on the negative X-axis direction side. The posture in which the speaker device 1 is mounted is not particularly limited, but for example, the speaker device 1 is hung directly or via a rail or the like from the ceiling so that the positive X-axis direction is vertically downward. The speaker device 1 may also be supported by a stand or the like so that the positive X-axis direction is horizontal.

[0051] 2, the speaker device 1 further includes a signal processing circuit 50, a processor 60, a memory 61, an input interface (I / F) 62, and a communication interface (I / F) 63. The signal processing circuit 50, the processor 60, the memory 61, the input interface 62, and the communication interface 63 are mounted on, for example, the board 30 shown in FIG.

[0052] The signal processing circuit 50 performs signal processing on the first audio signal input to the signal processing circuit 50 via the input interface 62, and generates a first output signal OUT1 and a second output signal OUT2. The first audio signal is an audio signal input from an output device for audio signals, such as an external sound source player. The first speaker 10 outputs a first sound S1 based on the first output signal OUT1 generated by the signal processing circuit 50. The second speaker 20 outputs a second sound S2 based on the second output signal OUT2 generated by the signal processing circuit 50. The first audio signal based on audio data stored in the memory 61 may be input to the signal processing circuit 50.

[0053] The signal processing circuit 50 includes a first FIR (Finite Impulse Response) filter 51, a second FIR filter 52, a low-pass filter 53, a high-pass filter 54, and an adder 55. The first FIR filter 51 is an example of a first filter, and the second FIR filter 52 is an example of a second filter.

[0054] The first FIR filter 51 and the second FIR filter 52 perform signal processing on the output of the low-pass filter 53, which is a signal in a partial frequency band of the first audio signal. The first FIR filter 51 and the second FIR filter 52 are adaptive filters set to filter characteristics determined by adaptive filter design. The first FIR filter 51 and the second FIR filter 52 adjust the phase and amplitude of the input signal for each frequency. Specifically, the first FIR filter 51 and the second FIR filter 52 apply (multiply) a control coefficient for the phase and amplitude for each frequency to the input signal and output the signal. The filter characteristics of the first FIR filter 51 and the second FIR filter 52 are determined by, for example, the information processing device 100. Details of the filter characteristics of the first FIR filter 51 and the second FIR filter 52 will be described later.

[0055] The first audio signal is input to the low-pass filter 53 via the input interface 62. The low-pass filter 53 is set to a predetermined cutoff frequency, and passes signals in a frequency band lower than the cutoff frequency, out of the first audio signal. The cutoff frequency of the low-pass filter 53 is, for example, 1 kHz or more and 5 kHz or less. The cutoff frequency of the low-pass filter 53 may be 2 kHz or more and 4 kHz or less. By inputting the first audio signal to the low-pass filter 53, it is possible to reduce the processing in the subsequent stages. In addition, it is difficult to cancel out the first sound S1 by overlapping the first sound S1 and the second sound S2 with each other in a high-pitched range, and even if the first sound S1 is blocked by the low-pass filter 53, the influence on the directivity of the speaker device 1 is small.

[0056] The first audio signal is input to the high-pass filter 54 via the input interface 62. The high-pass filter 54 is set to a predetermined cutoff frequency, and passes signals of the first audio signal having a frequency higher than the cutoff frequency. The cutoff frequency of the high-pass filter 54 is set to be the same as the cutoff frequency of the low-pass filter 53, for example.

[0057] The adder 55 adds the output of the first FIR filter 51 and the output of the high-pass filter 54, and outputs the added signal.

[0058] In the signal processing circuit 50, the first output signal OUT1 is generated based on the output of the first FIR filter 51. In the example shown in FIG. 2, the output of the first FIR filter 51 and the output of the high-pass filter 54 are added by the adder 55 to generate the first output signal OUT1. That is, the first output signal OUT1 is the output of the adder 55. Moreover, the second output signal OUT2 is generated based on the output of the second FIR filter 52. In the example shown in FIG. 2, the second output signal OUT2 is the output of the second FIR filter 52.

[0059] The processor 60 is a processing circuit that performs various information processes for the speaker device 1 to output sound. The processor 60 executes programs stored in the memory 61 to realize various functions.

[0060] The processor 60 stores information received from an external information processing device 100 or the like via the communication interface 63 in the memory 61. The information received by the processor 60 is, for example, the filter characteristics of the first FIR filter 51, the second FIR filter 52, the low-pass filter 53, and the high-pass filter 54. The processor 60 may also update the filter characteristics of the first FIR filter 51, the second FIR filter 52, the low-pass filter 53, and the high-pass filter 54 stored in the memory 61 based on the information received from the external information processing device 100 or the like. For example, when the speaker device 1 is powered on, the processor 60 reads the filter characteristics of the first FIR filter 51, the second FIR filter 52, the low-pass filter 53, and the high-pass filter 54 from the memory 61 and sets them in each filter.

[0061] The memory 61 is a storage device that stores the programs executed by the processor 60 and data necessary for the processes executed by the processor 60. The memory 61 stores, for example, the filter characteristics of the first FIR filter 51, the second FIR filter 52, the low-pass filter 53, and the high-pass filter 54. The memory 61 is configured, for example, with a semiconductor memory such as a flash memory. The storage device may include an HDD (Hard Disk Drive) or the like.

[0062] The input interface 62 receives a first audio signal from the outside and inputs the received first audio signal to the signal processing circuit 50. The input interface 62 is, for example, an analog audio input interface or an optical digital input interface, but may also be a Bluetooth (registered trademark) interface, a USB (Universal Serial Bus) interface, or a Wi-Fi (registered trademark) interface. Furthermore, when the first audio signal is an analog signal, AD conversion is performed in the signal processing circuit 50 or the input interface 62.

[0063] The communication interface 63 is a communication circuit for communicating with an external device such as the information processing device 100. The speaker device 1 is connected to an external device such as the information processing device 100 via the communication interface 63. The communication by the communication interface 63 may be wireless communication or wired communication. The communication standard of the communication by the communication interface 63 is not particularly limited. Note that the speaker device 1 does not need to be constantly connected to an external device such as the information processing device 100, and may be connected to an external device when communication is required, such as when determining the filter characteristics of the first FIR filter 51 and the second FIR filter 52 as described later.

[0064] The information processing device 100 is a computer for determining the filter characteristics of the first FIR filter 51 and the second FIR filter 52. The information processing device 100 has, for example, a processor, a memory, a communication interface, and a user interface. The information processing device 100 determines the filter characteristics of the first FIR filter 51 and the second FIR filter 52 by the processor executing a program stored in the memory. The filter characteristics of the first FIR filter 51 and the second FIR filter 52 determined by the information processing device 100 are transmitted to the speaker device 1.

[0065] [Filter characteristics of the 1st FIR filter and the 2nd FIR filter] Here, the filter characteristics of the first FIR filter 51 and the second FIR filter 52 will be described with reference to FIGS.

[0066] Fig. 3 is a diagram for explaining a method for designing the filter characteristics of the first FIR filter 51 and the second FIR filter 52. Fig. 4 is a flowchart showing an example of a method for determining the filter characteristics of the first FIR filter 51 and the second FIR filter 52.

[0067] First, the filter characteristics of the first FIR filter 51 and the second FIR filter 52 will be described in detail with reference to FIG.

[0068] The first speaker 10 emits the first sound S1 and the second speaker 20 emits the second sound S2, so that the first sound S1 and the second sound S2 overlap at the first position P1 and the second position P2, and the sound output by the speaker device 1 is heard as a composite sound of the first sound S1 and the second sound S2. The first FIR filter 51 and the second FIR filter 52 are adaptive filters set so that the sound output by the speaker device 1 has desired acoustic characteristics at the first position P1 and the second position P2. The first FIR filter 51 and the second FIR filter 52 have filter characteristics that adjust the phase and amplitude of the input signal for each frequency so that the sound pressure of the sound based on the first audio signal at the second position P2 is reduced by a predetermined value or more when the first sound S1 and the second sound S2 overlap, relative to the sound pressure of the sound based on the first audio signal at the first position P1. The filter characteristics include phase and amplitude characteristics for each frequency, specifically, phase and amplitude control coefficients for each frequency. Such filter characteristics can be realized by adaptive filter design, which will be described later.

[0069] As shown in FIG. 3, the first position P1 is located in front of the first speaker 10 in the positive direction of the X-axis. The second position P2 is located in a direction that forms a predetermined angle θ with respect to the positive direction of the X-axis with respect to the first speaker 10. The reference position for determining the predetermined angle θ is, for example, the sound output position of the first speaker 10, but may be shifted from the sound output position of the first speaker 10 in the X-axis direction. For example, the reference position for determining the predetermined angle θ may be located between the sound output position of the first speaker 10 and the sound output position of the second speaker 20. Also, for example, the reference position for determining the predetermined angle θ may be located between the center of the tip of the first horn 15 and the sound output position of the second speaker 20. The center of the tip of the first horn 15 is specifically the intersection point between a straight line that passes through the center of the first speaker 10 and is parallel to the positive direction of the X-axis, and a plane that includes the tip of the first horn 15 and is perpendicular to the positive direction of the X-axis. The predetermined angle θ is, for example, 60 degrees, but is set according to the angle range of the directivity of the speaker device 1. The predetermined angle θ is, for example, 30 degrees or more and 180 degrees or less. The predetermined angle θ may be 45 degrees or more and 120 degrees or less. The first position P1 and the second position P2 are located, for example, on concentric circles centered on the sound output position of the first speaker 10. The radius of the concentric circle is, for example, 0.5 m or more and 2 m or less.

[0070] The filter characteristics of the first FIR filter 51 and the second FIR filter 52 are set so that the composite sound of the first sound S1 and the second sound S2 based on the first audio signal has the desired amplitude frequency characteristics at the first position P1 and the second position P2. Specifically, in designing the filter characteristics of the first FIR filter 51 and the second FIR filter 52, the target amplitude frequency characteristic at the second position P2 is set lower by a predetermined sound pressure than the target amplitude frequency characteristic at the first position P1. As a result, at the second position P2, the second sound S2 is close to being in antiphase with the first sound S1, and the sound pressure at the second position P2 is lower than the sound pressure at the first position P1. In addition, the first FIR filter 51 has a filter characteristic that increases the amplitude of the input signal in a predetermined frequency range of frequencies below 1 kHz, for example. As a result, it is possible to compensate for the sound pressure in the low frequency range of the composite sound, which may be reduced by the overlap of the first sound S1 and the second sound S2 at the first position P1.

[0071] Next, a method in which the information processing device 100 determines the filter characteristics of the first FIR filter 51 and the second FIR filter 52 will be described with reference to Fig. 3 and Fig. 4. Fig. 4 shows a process in which the information processing device 100 performs adaptive filter design.

[0072] The information processing device 100 determines the filter characteristics of the first FIR filter 51 and the second FIR filter 52, for example, by using the microphone 111 arranged at the first position P1 and the microphone 112 arranged at the second position P2. The information processing device 100 first transmits a test audio signal to the speaker device 1 (step S11). The speaker device 1 receives the transmitted test audio signal by the input interface 62. The received test audio signal is processed by the signal processing circuit 50 and output to the first speaker 10 and the second speaker 20, and a test sound based on the test audio signal is output from the first speaker 10 and the second speaker 20. At this time, the initial values ​​of the filter characteristics of the first FIR filter 51 and the second FIR filter 52 are arbitrarily set by, for example, the user.

[0073] Next, the test sound sent from the speaker device 1 is collected by the microphone 111 and the microphone 112, and the information processing device 100 acquires the results of the test sound at the first position P1 and the second position P2 where the microphone 111 and the microphone 112 have collected the sound, respectively (step S12). Then, the information processing device 100 determines the filter characteristics of the first FIR filter 51 and the second FIR filter 52 based on the results of the test sound acquired in step S12 (step S13). Specifically, the user sets the target amplitude frequency characteristics of the test sound at the first position P1 and the second position P2 in the information processing device 100. The information processing device 100 determines the filter characteristics of the first FIR filter 51 and the second FIR filter 52 so that the amplitude frequency characteristics of the results of the test sound acquired at the first position P1 and the second position P2 asymptotically approach the target amplitude frequency characteristics at the first position P1 and the second position P2, respectively. In this case, a known algorithm such as an LMS (Least Mean Square) algorithm (least square method) is used to determine the filter characteristics.

[0074] For example, the amplitude frequency characteristic of the target test sound at the first position P1 is set to be the same as the amplitude frequency characteristic of the test audio signal to be transmitted. Also, for example, the amplitude frequency characteristic of the target test sound at the second position P2 is set to be an amplitude frequency characteristic lowered by a predetermined sound pressure from the amplitude frequency characteristic of the target test sound at the first position P1. The average value of the predetermined sound pressure in the frequency range in which the adaptive filter is designed is, for example, 10 dB or more and 30 dB or less. Note that such amplitude frequency characteristics of the target test sound at the first position P1 and the second position P2 are just examples, and ideal amplitude frequency characteristics at the first position P1 and the second position P2 are set according to the acoustic design, etc.

[0075] Next, the information processing device 100 determines whether or not a termination condition for the adaptive filter design is satisfied (step S14). The termination condition is, for example, whether or not the difference between the amplitude-frequency characteristics of the acquired test sound results at the first position P1 and the second position P2 and the amplitude-frequency characteristics of the target test sound for each of them is equal to or smaller than a threshold value.

[0076] If the difference exceeds the threshold value, the information processing device 100 determines that the termination condition is not satisfied (No in step S14), and performs the process from step S11 again using the filter characteristics determined above of the first FIR filter 51 and the second FIR filter 52. By repeating the processes from step S11 to step S13, the filter characteristics of the first FIR filter 51 and the second FIR filter 52 are designed so as to approach the amplitude-frequency characteristics of the target test sound at the first position P1 and the second position P2.

[0077] On the other hand, if the difference is equal to or smaller than the threshold value, the information processing device 100 determines that the termination condition is satisfied (Yes in step S14), and transmits filter characteristic information indicating the filter characteristics of the first FIR filter 51 and the second FIR filter 52 determined in step S13 to the speaker device 1 (step S15). The speaker device 1 receives the transmitted filter characteristic information via the communication interface 63, and the processor 60 updates the filter characteristics of the first FIR filter 51 and the second FIR filter 52 stored in the memory 61 to the filter characteristics indicated by the received filter characteristic information. The processor 60 also sets the updated filter characteristics to the first FIR filter 51 and the second FIR filter 52.

[0078] In step S14, the information processing device 100 may also determine that the end condition is satisfied if a predetermined time (number of times) has elapsed.

[0079] By such adaptive filter design by the information processing device 100, the filter characteristics of the first FIR filter 51 and the second FIR filter 52 are determined so that the difference in sound pressure of the test sound at the second position P2 relative to the sound pressure of the test sound at the first position P1 is lower by a predetermined sound pressure. The processor 60 operates the signal processing circuit 50 with the determined filter characteristics. As a result, the filter characteristics of the first FIR filter 51 and the second FIR filter 52 are set so that the sound pressure of the sound based on the first audio signal at the second position P2 is lower by a predetermined value or more than the sound pressure of the sound based on the first audio signal at the first position P1.

[0080] The adaptive filter design by the information processing device 100 is performed as an initial setting when the speaker device 1 is manufactured, for example, but may be performed after the speaker device 1 is installed.

[0081] [Effects, etc.] Next, the effect of the speaker device 1 will be described. With the above-described configuration, the speaker device 1 can obtain directivity for sounds in a wide frequency range. This will be described with reference to FIG. 5. FIG. 5 is a diagram for explaining the effect of the speaker device 1. In FIG. 5, the vertical axis indicates the difference in sound pressure of the sound based on the first audio signal at the second position P2 with respect to the sound pressure of the sound based on the first audio signal at the first position P1. That is, the more negative the vertical axis of FIG. 5 is, the lower the sound pressure of the sound based on the first audio signal at the second position P2 is compared to the sound pressure of the sound based on the first audio signal at the first position P1, indicating that the directivity is higher. In FIG. 5, the horizontal axis indicates frequency. In FIG. 5, the region A1 typically indicates the contribution of the first horn 15 to the directivity. In FIG. 5, the region A2 typically indicates the contribution of the second sound S2 of the second speaker 20 to the directivity by canceling out the first sound S1. 5, region A3 diagrammatically illustrates the contribution to directivity of a plurality of through holes 12. Note that the contribution to directivity illustrated by regions A1 to A3 is a diagrammatic example, and the size and frequency range of the regions are not limited to those illustrated in FIG.

[0082] The first sound S1 output from the first speaker 10 has its straightness in the positive direction of the X-axis increased by the first horn 15. The first horn 15 mainly increases the directivity in the high frequency range of 3 kHz or more, which has a high straightness. On the other hand, the lower the frequency of the sound, the less straight the sound is, and therefore the contribution of the first horn 15 to the directivity decreases, as shown in area A1. By increasing the size of the first horn 15, the straightness of a sound with a relatively low frequency can be increased, but this is disadvantageous in miniaturizing the speaker device 1.

[0083] The first sound S1 and the second sound S2 are sounds based on the outputs of the first FIR filter 51 and the second FIR filter 52, respectively. As described above, the first FIR filter 51 and the second FIR filter 52 have filter characteristics that adjust the phase and amplitude for each frequency of the first audio signal so that the sound pressure of the sound based on the first audio signal at the second position P2 is lower than the sound pressure of the sound based on the first audio signal at the first position P1 by a predetermined value or more. In other words, the phase and amplitude of the second sound S2 output from the second speaker 20 are adjusted so that the second sound S2 cancels out the first sound S1 by overlapping with the first sound S1 at the second position P2. The cancellation of the sounds caused by the overlapping of the first sound S1 and the second sound S2 is easier to achieve a phase difference that cancels out the sounds at lower frequencies, so the directivity is mainly increased in the low frequency range of 1 kHz or less. Furthermore, since the phase and amplitude of the first sound S1 and the second sound S2 for each frequency are adjusted by the first FIR filter 51 and the second FIR filter 52, the second sound S2 cancels out the first sound S1 even at frequencies higher than 1 kHz. Therefore, at frequencies where it is difficult to sufficiently increase the directivity with the first horn 15, it is possible to increase the directivity by canceling out the first sound S1 with the second sound S2. Therefore, in the speaker device 1, the area A1 and the area A2 overlap each other in the frequency range of 1 kHz to 3 kHz, for example, and the directivity can be increased.

[0084] In this way, the first horn 15 increases the straightness of high-frequency sounds, and the second sound S2 cancels out the first sound S1, thereby providing directionality for sounds in a wide frequency range in the speaker device 1. In addition, since the directivity can be increased for low and mid-frequency sounds without increasing the size of the first horn 15, the speaker device 1 can be made smaller.

[0085] In addition, the first speaker 10 outputs the first sound S1 in the positive direction of the X-axis by vibrating the diaphragm, and outputs a sound having an opposite phase to the first sound S1 to the internal space of the first housing 11. Since a plurality of through holes 12 are formed in the side wall of the first housing 11, the sound having an opposite phase to the first sound S1 outputted to the internal space of the first housing 11 is outputted to the outside of the first housing 11 from the plurality of through holes 12. The sound of the first sound S1 that wraps around in the left and right and up and down directions after leaving the first horn 15 is cancelled by the sound outputted from the plurality of through holes 12. Therefore, as shown in the area A3, the plurality of through holes 12 enhances the directivity in the low frequency range of 1 kHz or less where wraparound is particularly likely to occur. Therefore, at a frequency where the first horn 15 hardly contributes to the directivity, it is possible to enhance the directivity by canceling the first sound S1 with the sound outputted from the plurality of through holes 12.

[0086] Next, the measurement result of the directivity of the sound sent from the speaker device 1 will be described with reference to Figs. 6 and 7. Fig. 6 is a graph showing an example of the directivity of the sound sent from the speaker device according to the comparative example. Fig. 7 is a graph showing an example of the directivity of the sound sent from the speaker device 1 according to the present embodiment. Figs. 6 and 7 show the sound pressure (unit: dB) based on the sound pressure at the first position P1 as a reference. Figs. 6 and 7 also show the sound pressures of the sounds of 300 Hz, 500 Hz, 2 kHz, and 8 kHz. The speaker device according to the comparative example has a configuration in which the first horn 15 is not provided in the speaker device 1, and the first housing 11 does not have a plurality of through holes 12. In addition, in the speaker device according to the comparative example, the second sound S2 based on the second output signal OUT2 having an opposite phase to the first output signal OUT1 is output from the second speaker 20. In the speaker device 1 used in the sound measurement shown in FIG. 7, the above-mentioned predetermined angle θ is 60 degrees.

[0087] As shown in FIG. 6, the direction in which the sound pressure decreases varies depending on the frequency in the sound output from the speaker device according to the comparative example. In addition, for some sounds of different frequencies, the sound pressure cannot be sufficiently reduced in a direction other than the positive direction of the X-axis. In other words, the speaker device according to the comparative example cannot improve the directivity for sounds of a wide frequency range. In addition, in the speaker device according to the comparative example, even if the time at which the second sound S2 based on the second output signal OUT2 is output is delayed as in Patent Document 1, the direction in which the sound pressure decreases cannot be uniformed, and for some sounds of different frequencies, the sound pressure cannot be sufficiently reduced in a direction other than the positive direction of the X-axis.

[0088] In contrast, as shown in Fig. 7, in the sound output from the speaker device 1 according to the present embodiment, the sound pressure of the sound is low at any frequency in a direction forming an angle of 60 degrees with respect to the positive direction of the X-axis. In other words, in the speaker device 1 according to the present embodiment, the directivity can be increased for sounds in a wide frequency range. Also, in the sound output from the speaker device 1 according to the present embodiment, the range in which the sound pressure increases centered on the positive direction of the X-axis is narrower than that of the sound output from the speaker device according to the comparative example, and narrow directivity can be realized.

[0089] As described above, the speaker device 1 is provided with the first horn 15, the first sound S1 and the second sound S2 based on the outputs of the first FIR filter 51 and the second FIR filter 52 are output from the first speaker 10 and the second speaker 20, respectively, and a plurality of through holes 12 are formed in the first housing 11, thereby enabling the speaker device 1 to increase directionality for sounds in a wide frequency range.

[0090] Furthermore, the longer the distance between the output position of the first sound S1 of the first speaker 10 and the output position of the second sound S2 of the second speaker 20, the more effective it is to cancel out the first sound S1 with the second sound S2 at the second position P2. In the speaker device 1, the second speaker 20 outputs the second sound S2 in the negative X-axis direction opposite to the positive X-axis direction in which the first speaker 10 outputs the first sound S1, so that the distance between the output position of the first sound S1 of the first speaker 10 and the output position of the second sound S2 of the second speaker 20 can be increased while preventing the overall size of the speaker device 1 from increasing.

[0091] [Variation 1] Next, a first modification of the embodiment will be described. In the following description of the first modification, differences from the embodiment will be mainly described, and descriptions of commonalities will be omitted or simplified.

[0092] FIG. 8 is a plan view showing an example of the appearance of the speaker device 2 according to this modified example. FIG. 8 shows the appearance of the speaker device 2 when viewed from above (Z-axis positive direction side). Note that, for the sake of explanation, FIG. 8 shows a cross section of the first horn 15 and the second horn 25 cut in half along the XY plane, and the remaining half of the first horn 15 and the second horn 25 is actually present on the front side of the paper in FIG. 8 (Z-axis positive direction side). Also, in FIG. 8, the first speaker 10, the second speaker 20, and the substrate 30 housed in the first housing 11, the second housing 21, and the third housing 31, respectively, are shown by dashed lines. Also, in FIG. 8, the sound output from the second speaker 20 is typically shown by a dashed arrow D.

[0093] As shown in FIG. 8, the speaker device 2 differs from the speaker device 1 according to the embodiment in that a second horn 25 is further provided.

[0094] The second horn 25 emits the second sound S2 output from the second speaker 20 in the positive direction of the X axis. In the example shown in FIG. 8, the second horn 25 emits the second sound S2 output from the second speaker 20 and further diffused by the diffuser 23 in the positive direction of the X axis. The second horn 25 is disposed so as to surround the second speaker 20 and the diffuser 23. When viewed from the positive direction of the X axis, the center of the second speaker 20, the center of the second horn 25, and the center of the diffuser 23 coincide with each other. The second horn 25 is cylindrical, opens in the positive direction of the X axis and the negative direction of the X axis (in other words, the front-rear direction), and is attached to the end of the third housing 31 on the positive direction of the X axis so as to surround the space on the positive direction of the X axis of the diffuser 23. The opening of second horn 25 on the negative X-axis direction side is blocked by diffuser 23 and third housing 31, and the opening of second horn 25 on the positive X-axis direction side is open. The axial direction of second horn 25 coincides with the positive X-axis direction. When viewed from the positive X-axis direction side, second horn 25 extends further outward than first horn 15.

[0095] The second horn 25 has an inner surface 26 that gradually becomes wider in the positive direction of the X-axis. In the example shown in FIG. 8, the angle between the normal to the inner surface 26 and the positive direction of the X-axis is constant. The angle between the normal to the inner surface 26 and the positive direction of the X-axis may change in two or more steps, or may change continuously. The angle between the normal to the inner surface 26 and the positive direction of the X-axis (the average angle when it changes) is smaller than the above-mentioned predetermined angle θ, for example. Also, the angle between the normal to the inner surface 26 and the positive direction of the X-axis is smaller than the angle between the normal to the inner surface 16 of the first horn 15 and the positive direction of the X-axis, for example.

[0096] The shape of second horn 25 is not limited to a cylindrical shape, and may be a flat plate shape. In this case, an opening is provided in the center of second horn 25 in a plan view. Second horn 25 is attached to the end portion on the positive side of the X-axis of third housing 31, for example, so that the opening is blocked by diffuser 23 and third housing 31.

[0097] The presence of the second horn 25 makes it possible to suppress the second sound S2 from traveling in the negative direction on the X-axis beyond the second speaker 20 and to increase the amount of the second sound S2 traveling in the positive direction on the X-axis, thereby enabling the second sound S2 to be effectively sent to the second position P2.

[0098] Furthermore, in the absence of the second horn 25, the second sound S2 travels directly to the negative X-axis direction of the speaker device 2, so the path difference between the first sound S1 and the second sound S2 traveling to the negative X-axis direction of the speaker device 2 becomes large, and the first sound S1 is less likely to be cancelled by the second sound S2 on the negative X-axis direction of the speaker device 2. In contrast, the presence of the second horn 25 lengthens the travel path of the second sound S2 traveling to the negative X-axis direction of the speaker device 2, so the path difference between the first sound S1 and the second sound S2 traveling to the negative X-axis direction of the speaker device 2 becomes smaller than when the second horn 25 is not present. Therefore, the first sound S1 is more likely to be cancelled by the second sound S2 even on the negative X-axis direction of the speaker device 2.

[0099] In the speaker device 2, the second speaker 20 outputs the second sound S2 in the negative direction of the X-axis, but the second speaker 20 may output the second sound S2 in the positive direction of the X-axis. FIG. 9 is a plan view showing an example of the appearance of another speaker device 2A according to this modification. FIG. 9 shows the appearance of the speaker device 2A when viewed from above (the positive direction of the Z-axis). In FIG. 9, for the purpose of explanation, a cross section of the first horn 15 and the second horn 25 cut in half along the XY plane is shown, and the remaining half of the first horn 15 and the second horn 25 is actually present on the front side of the paper in FIG. 9 (the positive direction of the Z-axis). In FIG. 9, the first speaker 10, the second speaker 20, and the substrate 30 housed in the first housing 11, the second housing 21, and the third housing 31, respectively, are shown by dashed lines.

[0100] As shown in FIG. 9, in the speaker device 2A, the second speaker 20, the second housing 21 and the diffuser 23 are arranged in the opposite direction to those of the speaker device 2 in the X-axis direction.

[0101] Specifically, in the speaker device 2A, the second speaker 20 outputs the second sound S2 in the positive direction of the X-axis. The second speaker 20 is provided at the end of the second housing 21 on the positive side of the X-axis.

[0102] Moreover, in the speaker device 2A, the second housing 21 is connected to an end portion on the negative X-axis direction side of the first housing 11 via a connection member 32. An opening in which the second speaker 20 is installed is provided at the end portion on the positive X-axis direction side of the second housing 21, and the opening is blocked by the second speaker 20. Moreover, the end portion on the negative X-axis direction side of the second housing 21 is blocked by a plate-shaped member.

[0103] In the speaker device 2A, the diffuser 23 is disposed on the output side of the second speaker 20 from which the second sound S2 is output, that is, on the positive side of the X-axis from the second speaker 20, facing the second speaker 20. The diffuser 23 is fixed to an end of the first housing 11 on the negative side of the X-axis.

[0104] In speaker device 2A, second horn 25 is disposed on the positive X-axis direction side with respect to second speaker 20. Second horn 25 is cylindrical, opens in the positive X-axis direction and the negative X-axis direction (in other words, the front-to-rear direction), and is attached to the end of second housing 21 on the positive X-axis direction side so as to surround the space on the positive X-axis direction side of diffuser 23. The opening on the negative X-axis direction side of second horn 25 is blocked by second speaker 20 and second housing 21, and the opening on the positive X-axis direction side of second horn 25 is open.

[0105] Also in the speaker device 2A, by providing the second horn 25, the same effect as in the speaker device 2 can be obtained.

[0106] The speaker device 2A may not include the second horn 25. That is, in the speaker device 1 according to the embodiment, the second speaker 20, the second housing 21, and the diffuser 23 may be arranged in the opposite direction, and the second speaker 20 may output the second sound S2 in the positive direction of the X-axis.

[0107] [Variation 2] Next, a description will be given of Modification 2 of the embodiment. In the following description of Modification 2, differences from the embodiment and Modification 1 will be mainly described, and descriptions of commonalities will be omitted or simplified.

[0108] FIG. 10 is a block diagram showing an example of a functional configuration of the speaker device 3 according to this modification.

[0109] 10, the speaker device 3 differs from the speaker device 1 according to the embodiment in that, instead of the signal processing circuit 50, the speaker device 3 includes a signal processing circuit 350 having a configuration in which an adder 56 is further added to the signal processing circuit 50. The appearance of the speaker device 3 is, for example, any of the appearances of the speaker devices described in the above embodiment and modification example 1.

[0110] The adder 56 generates and outputs a second output signal OUT2 by adding the output of the second FIR filter 52 and a second audio signal indicating a masking sound. The masking sound is a sound unrelated to the first audio signal, for example, an environmental sound such as a river sound. For example, audio data of the masking sound is stored in the memory 61, and the processor 60 generates a second audio signal based on the audio data and inputs it to the adder 56. Note that the speaker device 3 may further include an input interface for receiving the second audio signal, and the second audio signal from the outside may be input to the adder 56 via the input interface. Also, the second audio signal may be subjected to signal processing by the signal processing circuit 350 or another signal processing circuit before being input to the adder 56.

[0111] In the speaker device 3, the second output signal OUT2 is obtained by adding the second audio signal to the output of the second FIR filter 52, so that the second sound S2 based on the second output signal OUT2 includes a masking sound that is unrelated to the sound to be heard by the speaker device 3, in addition to a cancellation sound that cancels out the first sound S1. At the second position P2, the sound pressure of the sound based on the first audio signal is lower than that at the first position P1, but it is difficult to make it zero. Therefore, when the speaker device 3 is installed in a quiet environment, the sound based on the first audio signal may be heard at a level that bothers people even at the second position P2. According to the speaker device 3, the masking sound can be heard around the speaker device 3, so that the sound based on the first audio signal can be made difficult to hear at the second position P2 by the masking sound, even when the speaker device 3 is installed in a quiet environment.

[0112] [Variation 3] Next, a description will be given of Modification 3 of the embodiment. In the following description of Modification 3, differences from the embodiment and Modifications 1 and 2 will be mainly described, and descriptions of commonalities will be omitted or simplified.

[0113] In this modified example, an example in which the speaker device further includes a sound absorbing material will be described. As will be described in detail below, the sound absorbing material absorbs sound, and thereby the sound pressure can be reduced and the directivity can be further improved on the negative X-axis side of the speaker device where the first sound S1 is less likely to be cancelled out by the second sound S2.

[0114] First, the configuration of the speaker device according to this modified example will be described.

[0115] Fig. 11 is a plan view showing an example of the appearance of the speaker device 4 according to this modified example. Fig. 11 shows the appearance of the speaker device 4 when viewed from above (Z-axis positive direction side). For the sake of explanation, Fig. 11 shows a cross section of the first horn 15, the sound absorbing material 70, and the sound reflecting material 71 cut in half along the XY plane, and the remaining half of the first horn 15, the sound absorbing material 70, and the sound reflecting material 71 is actually located on the front side of the paper in Fig. 11 (Z-axis positive direction side). In Fig. 11, the first speaker 10, the second speaker 20, and the substrate 30 housed in the first housing 11, the second housing 21, and the third housing 31, respectively, are shown by dashed lines.

[0116] 11, the speaker device 4 differs from another speaker device 2A according to the first modification of the embodiment in that the speaker device 4 does not include the second horn 25 and further includes a sound absorbing material 70 and a sound reflecting material 71. Note that the speaker device 4 does not necessarily have to include the sound reflecting material 71.

[0117] The sound absorbing material 70 is a plate-shaped member that absorbs the first sound S1 and the second sound S2 traveling in the negative direction of the X-axis. The sound absorbing material 70 is arranged so as to include a portion surrounding the first speaker 10 and the second speaker 20 when viewed from the positive direction of the X-axis. The sound absorbing material 70 extends outward beyond the first speaker 10 and the second speaker 20 when viewed from the positive direction of the X-axis.

[0118] When viewed from the positive direction of the X-axis, the center of the sound-absorbing material 70 coincides with, for example, the center of the first speaker 10. The outer shape of the sound-absorbing material 70 when viewed from the positive direction of the X-axis is, for example, rectangular, but may be other shapes such as circular or elliptical.

[0119] The sound-absorbing material 70 has a first surface 70a on the positive side of the X-axis and a second surface 70b located on the negative side of the X-axis from the first surface 70a as two surfaces facing each other in the thickness direction of the sound-absorbing material 70. In the example shown in Fig. 11, the first surface 70a and the second surface 70b are perpendicular to the thickness direction of the sound-absorbing material 70 and parallel to each other.

[0120] At least a part of the sound absorbing material 70 is located in the X-axis direction at the same position as the outlet position of the second sound S2 in the speaker device 4, or on the negative X-axis side of the outlet position. In the case where the second horn 25 is not provided as in the speaker device 4, the outlet position of the second sound S2 is the sound output position of the second speaker 20. In the example shown in FIG. 11, the first surface 70a is located in the X-axis direction at the same position as the sound output position of the second speaker 20. Therefore, the entire sound absorbing material 70 is located in the X-axis direction at the same position as the sound output position of the second speaker 20, or on the negative X-axis side of the sound output position of the second speaker 20. The first surface 70a may be located in the X-axis direction at the negative X-axis side of the sound output position of the second speaker 20.

[0121] The sound-absorbing material 70 is attached to a side surface of the second housing 21. In the example shown in Fig. 11, a through hole is provided in the center of the sound-absorbing material 70, and the sound-absorbing material 70 and the second housing 21 are fixed together so that the second housing 21 is disposed in the through hole. The sound-absorbing material 70 may be attached directly to the second housing 21, or may be attached to the second housing 21 via an attachment member (not shown). In this case, the sound-absorbing material 70 and the second housing 21 do not need to be in contact with each other.

[0122] In the speaker device 4, the predetermined angle θ for defining the second position P2 is, for example, an angle between a first angle α1 formed by the direction in which the first surface 70a extends and the X-axis positive direction in a cross-sectional view on a plane parallel to the X-axis positive direction passing through the center of the first speaker 10, and a second angle α2 formed by a direction connecting the sound output position of the first speaker 10 and the end of the first surface 70a (in other words, the outer peripheral position of the first surface 70a) in the cross-sectional view. As a result, the sound pressure of the sound heading in the direction along the sound absorbing material 70 is reduced, so that the sound is less likely to wrap around to the X-axis negative direction side, and the sound pressure of the sound on the X-axis negative direction side of the sound absorbing material 70 can be effectively reduced. In addition, the sound absorbing material 70 can be made smaller. The cross-sectional view plane is also the plane on which the first position P1 and the second position P2 are located. In FIG. 11, for the sake of explanation, the X-axis plus direction (D1 in the figure) in which the first sound S1 is output from the first speaker 10, the direction in which the first surface 70a extends (D2 in the figure), and the arrow indicating the direction connecting the sound output position of the first speaker 10 and the end of the first surface 70a (D3 in the figure) are shown starting from the sound output position of the first speaker 10. Therefore, in FIG. 11, the arrow indicating the direction in which the first surface 70a extends is translated from the position of the first surface 70a to the sound output position of the first speaker 10. In addition, the predetermined angle θ being an angle between the first angle α1 and the second angle α2 includes the case where the predetermined angle θ is the same angle as the first angle α1 and the case where the predetermined angle θ is the same angle as the second angle α2. The predetermined angle θ may be the same angle as the first angle α1.

[0123] The difference between the first angle α1 and the second angle α2 is, for example, 20 degrees or less. The difference between the first angle α1 and the second angle α2 may be 10 degrees or less.

[0124] 11, the sound absorbing material 70 is flat, and the first angle α1 is 90 degrees. This effectively prevents the sound pressure characteristics of the sound emitted by the speaker device 4 from being disturbed when a part of the sound emitted by the speaker device 4 is reflected by the sound absorbing material 70 and the sound reflecting material 71. The first angle α1 may be other than 90 degrees, and may be, for example, 45 degrees or more and 135 degrees or less.

[0125] The sound absorbing material constituting the sound absorbing material 70 is not particularly limited, but the sound absorbing material 70 includes, for example, a Helmholtz resonator or a foam having open cells such as a sponge. The sound absorbing material 70 may be a composite material including a plurality of types of sound absorbing materials. For example, the sound absorbing material 70 may include a laminate of a plate-shaped Helmholtz resonator and a plate-shaped foam. When the sound absorbing material 70 includes a Helmholtz resonator, it can absorb low-midrange sounds, the directionality of which is difficult to increase by the first horn 15.

[0126] The sound reflecting material 71 is a plate-like member that reflects components of the first sound S1 and the second sound S2 that are incident on the sound absorbing material 70 and that are not absorbed by the sound absorbing material 70. By reflecting these components, the sound pressure can be further reduced on the negative X-axis direction side of the speaker device 4, thereby improving the directivity.

[0127] The sound reflecting material 71 is disposed on the negative side of the X-axis with respect to the sound absorbing material 70. The sound reflecting material 71 is provided on a second surface 70b of the sound absorbing material 70. When viewed from the positive side of the X-axis, the outline of the sound reflecting material 71 coincides with, for example, the sound absorbing material 70. When viewed from the positive side of the X-axis, the entire sound absorbing material 70 overlaps with the sound reflecting material 71.

[0128] The sound reflecting material 71 is attached to the side surface of the second housing 21 together with the sound absorbing material 70. In the example shown in Fig. 11, a through hole is provided in the center of the sound reflecting material 71, and the sound reflecting material 71 and the second housing 21 are fixed together so that the second housing 21 is disposed in the through hole.

[0129] The sound reflecting material 71 is, for example, a metal or resin plate material. The sound reflecting material 71 may be integrated with the sound absorbing material 70.

[0130] Next, the measurement results of the directivity of the sound sent from the speaker device 4 will be described.

[0131] FIG. 12 is a graph showing an example of the directivity of the sound emitted from the speaker device 4 according to this modification, which has a configuration in which the sound absorbing material 70 and the sound reflecting material 71 are removed. FIG. 13 is a graph showing an example of the directivity of the sound emitted from the speaker device 4 according to this modification. In FIG. 12 and FIG. 13, the sound pressure (unit: dB) is shown when the sound pressure at the first position P1 is used as a reference. In FIG. 12 and FIG. 13, the sound pressures of the sounds of 300 Hz, 500 Hz, 2 kHz, and 8 kHz are shown. In the speaker device used in the sound measurement shown in FIG. 12, the above-mentioned predetermined angle θ is 90 degrees. In the speaker device 4 used in the sound measurement shown in FIG. 13, the above-mentioned predetermined angle θ and the first angle α1 are both 90 degrees, and the second angle α2 is 95 degrees.

[0132] As shown in FIG. 12, even in a speaker device having a configuration excluding sound-absorbing material 70 and sound-reflecting material 71, the sound pressure of all sounds at any frequency is low in a direction forming an angle of 90 degrees with respect to the positive X-axis direction relative to the first speaker 10, and the directionality for sounds over a wide frequency range is improved compared to the speaker device of the comparative example shown in FIG. 6 above.

[0133] As shown in FIG. 13, the sound output by the speaker device 4 according to this modification has a lower sound pressure at each frequency on the negative X-axis side than the first speaker 10 in the case shown in FIG. 12. This is due to the following three effects. The first point is that the first sound S1 and the second sound S2 traveling in the negative X-axis direction are absorbed by the sound absorbing material 70. The second point is that the predetermined angle θ is 90 degrees, which is the same as the first angle α1, so that the sound pressure of the sound traveling in the direction along the sound absorbing material 70 is lowered, and the sound is less likely to wrap around in the negative X-axis direction. The third point is that the sound reflecting material 71 reflects the components of the first sound S1 and the second sound S2 that are incident on the sound absorbing material 70 and are not absorbed by the sound absorbing material 70.

[0134] Furthermore, because the first angle α1 is 90 degrees, no disturbance occurs in the sound pressure characteristics of the sound sent to the positive X-axis direction from the first speaker 10. This is because the components of the first sound S1 and the second sound S2 that are incident on the sound-absorbing material 70 and that are not absorbed by the sound-absorbing material 70 and are reflected by the sound-reflecting material 71 overlap with the characteristics of the sound sent to the positive X-axis direction.

[0135] As described above, it can be seen that the speaker device 4 is provided with the sound absorbing material 70, so that the sound pressure can be reduced and the directivity can be improved on the negative X-axis direction side of the speaker device 4.

[0136] The positions where the sound absorbing material 70 and the sound reflecting material 71 are attached are not limited to the example shown in FIG. 11. FIGS. 14 to 16 are plan views showing examples of the appearance of other speaker devices 4A to 4C according to this modification, respectively. For the sake of explanation, FIGS. 14 to 16 show cross sections of the first horn 15, the second horn 25 (only in the case of FIG. 16), the sound absorbing material 70, and the sound reflecting material 71 cut in half along the XY plane, and the remaining halves of the first horn 15, the second horn 25 (only in the case of FIG. 16), the sound absorbing material 70, and the sound reflecting material 71 are actually located on the front side of the paper in FIGS. 14 to 16 (the Z-axis plus direction side). In addition, in FIGS. 14 to 16, the first speaker 10, the second speaker 20, and the substrate 30 housed in the first housing 11, the second housing 21, and the third housing 31, respectively, are shown by dashed lines.

[0137] In the speaker device 4A shown in FIG. 14, the sound absorbing material 70 is attached to the side surface of the second housing 21 via a sound reflecting material 71. In the speaker device 4A, in the X-axis direction, the first surface 70a is located on the X-axis positive side of the sound output position of the second speaker 20, and the second surface 70b is located at the same position as the sound output position of the second speaker 20. The second surface 70b may be located on the X-axis negative side of the sound output position of the second speaker 20 in the X-axis direction. In addition, in the speaker device 4A, a gap is provided between the second housing 21 and the sound absorbing material 70 so that the second sound S2 can travel in the X-axis positive direction when viewed from the X-axis positive direction.

[0138] 15, the sound absorbing material 70 is attached to the third housing 31 together with the sound reflecting material 71. In the example shown in FIG. 15, the sound absorbing material 70 is attached to the side surface of the third housing 31 together with the sound reflecting material 71. At least one of the sound absorbing material 70 and the sound reflecting material 71 may be attached to the rear surface (the surface on the negative X-axis direction side) of the third housing 31. At least one of the sound absorbing material 70 and the sound reflecting material 71 may be attached to an attachment location such as a ceiling or a wall on which the speaker device 4B is attached.

[0139] In addition, in the speaker device 4C shown in FIG. 16, the second horn 25 is provided, and the sound absorbing material 70 is attached to the second horn 25. That is, the speaker device 4C has a configuration in which the sound absorbing material 70 and the sound reflecting material 71 are added to the speaker device 2A. In the example shown in FIG. 16, the sound absorbing material 70 is attached to the end of the second horn 25 on the positive side of the X-axis. In the speaker device 4C, the sound absorbing material 70 is arranged to include a portion surrounding the second horn 25 when viewed from the positive side of the X-axis, and spreads outward from the second horn 25. The sound absorbing material 70 may be attached to the second horn 25 via the sound reflecting material 71. In addition, the sound absorbing material 70 may be attached to a portion other than the end of the second horn 25, and may be attached to an attachment portion such as a ceiling or a wall to which the second housing 21, the third housing 31, or the speaker device 4C is attached, instead of the second horn 25.

[0140] In addition, in the speaker device 4C, at least a part of the sound absorbing material 70 is located in the same position as the outlet position of the second sound S2 in the speaker device 4C in the X-axis direction, or on the negative X-axis side of the outlet position. In the case where the second horn 25 is provided as in the speaker device 4C, the outlet position of the second sound S2 is the tip position of the second horn 25 on the positive X-axis side. In the example shown in Fig. 15, the entire sound absorbing material 70 is located on the negative X-axis side of the outlet position of the second sound S2 in the speaker device 4C.

[0141] In each of the above examples, the sound absorbing material 70 and the sound reflecting material 71 are described as being installed in a configuration of the speaker device 2A excluding the second horn 25, or in the configuration of the speaker device 2A, but they may be installed in any of the above-mentioned speaker devices 1, 2, and 3.

[0142] (Other embodiments) As described above, the embodiments (including modified examples) have been described as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are appropriately made. In addition, it is also possible to combine the components described in the above embodiments to create new embodiments.

[0143] Also, for example, in the above embodiment, first housing 11 is formed with a plurality of through holes 12, but this is not limited thereto. First housing 11 may not be formed with a plurality of through holes 12, and the internal space of first housing 11 may be a closed space.

[0144] Also, for example, in the above embodiment, at least one of the first speaker 10 and the second speaker 20 may be composed of a plurality of speakers.

[0145] Also, for example, in the above embodiment, the filter characteristics of the first FIR filter 51 and the second FIR filter 52 are determined by performing adaptive filter design, but this is not limiting. The filter characteristics of the first FIR filter 51 and the second FIR filter 52 may be determined by a method other than adaptive filter design. For example, the filter characteristics of the first FIR filter 51 and the second FIR filter 52 may be designed using simulation or the like.

[0146] Also, for example, in the above-described embodiment, the signal processing circuits 50 and 350 have the low-pass filter 53 and the high-pass filter 54, but are not limited to this. For example, the first audio signal may be directly input to the first FIR filter 51 and the second FIR filter 52.

[0147] In the above embodiment, the process executed by a specific processing circuit such as a processor may be executed by another processing circuit. The order of multiple processes may be changed, or multiple processes may be executed in parallel. The number of processors that execute the program may be one or more. That is, centralized processing or distributed processing may be performed.

[0148] In addition, the general or specific aspects of the present disclosure may be realized in a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM. In addition, the present disclosure may be realized in any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. For example, the present disclosure may be realized as a speaker system including a speaker device and an information processing device. The speaker system may be realized by multiple devices, or may be realized as a single device. In addition, when the speaker system is realized by multiple devices, each component of the speaker system may be distributed among the multiple devices in any manner.

[0149] In addition, the present disclosure also includes forms obtained by applying various modifications to the embodiments that would come to mind by a person skilled in the art, and forms realized by arbitrarily combining the components and functions of the embodiments as long as they do not deviate from the spirit of the present disclosure. [Industrial Applicability]

[0150] The present disclosure can be used in a speaker device or the like having directionality. [Explanation of symbols]

[0151] 1, 2, 2A, 3, 4, 4A, 4B, 4C Speaker device 10 1st Speaker 11 First cabinet 12 Through hole 15 First Horn 16, 26 Inside 20 2nd Speaker 21 Second cabinet 23 Diffuser 25 2nd Horn 30 Substrate 31 3rd cabinet 32 Connection parts 50, 350 Signal processing circuit 51 1st FIR filter 52 2nd FIR filter 53 Low-pass filter 54 High Pass Filter 55, 56 Adder 60 processors 61 Memory 62 Input Interface 63 Communication Interface 70 Sound absorbing material 70a 1st page 70b 2nd side 71 Sound reflective material 100 Information processing device 111, 112 Mike OUT1 First output signal OUT2 Second output signal P1 1st position P2 2nd position S1 First sound S2 2nd note

Claims

1. a signal processing circuit that performs signal processing on the input first audio signal to generate a first output signal and a second output signal; a first speaker that outputs a first sound based on the first output signal in a first direction; a first horn that emits the first sound output from the first speaker in the first direction; a second speaker that is disposed on a second direction side, which is an opposite direction to the first direction, with respect to the first speaker and outputs a second sound based on the second output signal; The signal processing circuit includes: a first filter and a second filter for performing signal processing on a signal in at least a part of a frequency band of the first audio signal; the first output signal is generated based on an output of the first filter; the second output signal is generated based on an output of the second filter; the first filter and the second filter have filter characteristics that adjust a phase and an amplitude for each frequency of a signal in at least a part of a frequency band of the first audio signal such that a sound pressure of a sound based on the first audio signal at a second position is reduced by a predetermined value or more when the first sound and the second sound overlap with each other, relative to a sound pressure of a sound based on the first audio signal at a first position; the first position is located in front of the first speaker in the first direction; The second position is located in a direction that forms a predetermined angle with respect to the first direction with respect to the first speaker. Speaker device.

2. the signal processing circuit includes a low-pass filter to which the first audio signal is input; the first filter and the second filter perform signal processing on the output of the low-pass filter; 2. The speaker device according to claim 1.

3. a cylindrical housing having an axial direction aligned in the first direction, The first speaker is provided at an end of the housing on the first direction side, A plurality of through holes are formed in a circumferential side wall of the housing.

3. The speaker device according to claim 1 or 2.

4. The second speaker outputs the second sound in the second direction.

3. The speaker device according to claim 1 or 2.

5. a diffuser that diffuses the second sound output from the second speaker; 3. The speaker device according to claim 1 or 2.

6. a second horn that emits the second sound output from the second speaker in the first direction; 3. The speaker device according to claim 1 or 2.

7. the signal processing circuit has an adder that generates the second output signal by adding a second audio signal indicative of a masking sound to an output of the second filter; 3. The speaker device according to claim 1 or 2.

8. a plate-shaped sound absorbing material disposed so as to include a portion surrounding the first speaker and the second speaker when viewed from the first direction; The sound absorbing material absorbs the first sound and the second sound traveling in the second direction, the predetermined angle is an angle between a first angle formed by a direction in which a surface of the sound absorbing material on the first direction side extends and the first direction in a cross-sectional view on a plane parallel to the first direction passing through the center of the first speaker, and a second angle formed by a direction connecting a sound output position of the first speaker and an end of the surface in the cross-sectional view and the first direction, 3. The speaker device according to claim 1 or 2.

9. A plate-shaped sound reflecting material is provided on the second direction side of the sound absorbing material.

9. The speaker device according to claim 8.

10. the first angle is 90 degrees; 9. The speaker device according to claim 8.

Images