Speaker device

Abstract

A speaker device (1) comprises: a signal processing circuit that performs signal processing on an inputted first sound signal and generates a first output signal and a second output signal; a first speaker (10) that outputs, in a first direction, a first sound (S1) based on the first output signal; a first horn (15) that emits, in the first direction, the first sound (S1) outputted from the first speaker (10); and a second speaker (20) that is disposed, relative to the first speaker (10), in a second direction 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 for adjusting the phase and amplitude of inputted signals at each frequency so that the sound pressure of a sound based on the first sound signal at a second position decreases by a predetermined value or more with respect to the sound pressure of a sound based on the first sound signal at a first position.

Description

Speaker device

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

[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.

[0004] JP 2013-33104 A

[0005] The present disclosure provides a speaker device that has directionality for sounds in a wide frequency range.

[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 and generates 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, wherein the signal processing circuit has a first filter and a second filter that perform signal processing on a signal in at least a part of a frequency band of the first audio signal, and the first output signal is output through the first filter. 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 the 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 the first speaker in the first direction.

[0007] According to the present disclosure, it is possible to provide a speaker device that has directionality for sounds in a wide frequency range.

[0008] FIG. 1 is a plan view showing an example of the appearance of a speaker device according to an embodiment. FIG. 2 is a block diagram showing an example of the functional configuration of the speaker device according to the embodiment. FIG. 3 is a diagram for explaining a design method for filter characteristics of a first FIR filter and a second FIR filter. FIG. 4 is a flowchart showing an example of a method for determining the filter characteristics of a first FIR filter and a second FIR filter. FIG. 5 is a diagram for explaining an effect of the speaker device according to the embodiment. FIG. 6 is a graph showing an example of the directivity of sound output from a speaker device according to a comparative example. FIG. 7 is a graph showing an example of the directivity of sound output from a speaker device according to the embodiment. FIG. 8 is a plan view showing an example of the appearance of a speaker device according to a first modification of the embodiment. FIG. 9 is a plan view showing an example of the appearance of another speaker device according to the first modification of the embodiment. FIG. 10 is a block diagram showing an example of the functional configuration of a speaker device according to a second modification of the embodiment. FIG. 11 is a plan view showing an example of the appearance of a speaker device according to a third modification of the embodiment. 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 Modification 3 of the embodiment. Fig. 13 is a graph showing an example of the directivity of sound emitted from the speaker device according to Modification 3 of the embodiment. Fig. 14 is a plan view showing an example of the appearance of a first alternative speaker device according to Modification 3 of the embodiment. Fig. 15 is a plan view showing an example of the appearance of a second alternative speaker device according to Modification 3 of the embodiment. Fig. 16 is a plan view showing an example of the appearance of a third alternative speaker device according to Modification 3 of the embodiment.

[0009] (Summary of the Present Disclosure) As an overview 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 and generates 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, wherein the signal processing circuit has a first filter and a second filter that perform signal processing on a signal in at least a part of a frequency band of the first audio signal, and the first output signal is output through the first filter. 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 the 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 the first speaker in the first direction.

[0011] This allows for a speaker device that has directivity for sounds over a wide frequency range. Specifically, the first horn enhances the linearity of the first sound, thereby improving the directivity of the sound emitted by the speaker device. This improved directivity is particularly effective for high-frequency sounds that have a high linearity. Furthermore, the first sound and the second sound are based on the outputs of the first and second filters. The sound pressure of the sound based on the first audio signal at the second position is reduced by a predetermined value or more relative to the sound pressure of the sound based on the first audio signal at the first position due to the first sound being canceled out by the second sound. This improves the directivity of sounds in the mid-to-low frequency range, where interference between the first sound and the second sound is likely to occur. Furthermore, because the first and second filters adjust the phase and amplitude of the first audio signal for each frequency, the first sound is canceled out by the second sound over a wider frequency range, and the amount of cancellation is greater, than when a sound that is simply the opposite phase of the first sound is 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] This allows sounds of opposite phase to the first sound to be output from the multiple through holes, and the first sound can be canceled out by the sounds of 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 allows 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 to be increased 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 a speaker device according to any one of the first to fourth aspects, and includes a diffuser that diffuses the second sound output from the second speaker.

[0019] This allows the second sound to be diffused, and the range in which the second sound can cancel out the first sound can be expanded.

[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 is provided with a second horn that emits the second sound output from the second speaker in the first direction.

[0021] This allows the second horn to prevent the path difference between the first sound and the second sound traveling in the second direction of the speaker device from becoming too large, making it easier for the first sound to be canceled out by the second sound even in the second direction 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 the output of the second filter.

[0023] This causes the second sound to include a masking sound, so that even when 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 by the masking sound.

[0024] Furthermore, 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 that is 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 that are about to travel in the second direction side, and the predetermined angle is an angle between a first angle formed by a direction in which the 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 that passes 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 the end of the surface and the first direction in the cross-sectional view.

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

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

[0027] This allows the components of the first and second sounds that are 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 increasing the directionality.

[0028] Furthermore, 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, wherein the first angle is 90 degrees.

[0029] This makes it possible to prevent the sound pressure characteristics of the sound emitted by the speaker device from being disturbed when part of the sound emitted by the speaker device is reflected by the sound-absorbing material.

[0030] Hereinafter, embodiments will be described with reference to the drawings as appropriate. However, more detailed explanations than necessary may be omitted. For example, detailed explanations of well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art.

[0031] The present inventors have provided the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims.

[0032] In the following embodiments, for convenience of explanation, the front-to-rear direction is designated as the X-axis direction, the left-to-right direction (horizontal direction) as the Y-axis direction, and the up-to-down direction as the Z-axis direction. However, these correspondences do not limit the posture of the speaker device according to the present disclosure during manufacture or use. Furthermore, the X-axis, Y-axis, and Z-axis represent the three axes of a three-dimensional Cartesian coordinate system. In the following description, for example, the positive X-axis direction indicates the direction of the arrow on the X-axis, and the negative X-axis direction indicates the direction opposite to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. The positive X-axis direction (forward) is an example of a first direction, and the negative X-axis direction (rear) is an example of a second direction. Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like in each figure are not necessarily the same.

[0033] Furthermore, 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) Hereinafter, a speaker device according to the present embodiment will be described.

[0035] [Configuration] First, the configuration of the speaker device according to this embodiment will be described with reference to FIGS. 1 and 2. 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 as viewed from above (the positive Z-axis direction). Note that, for the sake of explanation, FIG. 1 shows a cross section of the first horn 15 cut in half along the XY plane. In reality, the remaining half of the first horn 15 is located on the front side of the page in FIG. 1 (the positive Z-axis direction). 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, sound output from the first speaker 10 through the first horn 15 is schematically indicated by a solid arrow A, sound output from the multiple through-holes 12 is typically indicated by a dashed arrow B, and sound output from the second speaker 20 is typically indicated by a dashed 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, approximately 40 cm long in the front-to-rear direction and approximately 20 cm long in the left-to-right direction. The speaker device 1 is configured to include two speakers, namely, a first speaker 10 and a second speaker 20, and while having directionality, it is easy to make it compact and to easily achieve high-quality sound. The speaker device 1 is expected to be installed in, for example, shared spaces in homes, offices, commercial facilities, etc.

[0039] The speaker device 1, which is a directional speaker, allows people 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 outside the predetermined range. In particular, with a directional speaker, it is important to reduce the sound pressure of sounds in a wide frequency range 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 sounds in a wide frequency range 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, which will be described later. The first speaker 10 is composed of, for example, a diaphragm, a magnetic circuit, a voice coil, etc. 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-to-rear direction, and thereby the first sound S1 is output in the positive direction of the X-axis.

[0041] The first housing 11 is a cylindrical housing with its axis aligned in the positive direction of the X axis. The first housing 11 has an internal space for accommodating the first speaker 10, and is also referred to as 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 side of the X axis, and this opening is closed by the first speaker 10. In addition, the end of the first housing 11 on the negative side of the X axis is closed by a plate-shaped member. When viewed from the positive 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, connecting the internal space of the first housing 11 with the outside of the first housing 11. Sound that is in the 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. Note that 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 its center. The first horn 15 is disposed on the positive side of the X axis relative 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 and has openings in the positive and negative directions of the X axis (in other words, the front-to-back direction). It 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, while 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] The first horn 15 has an inner surface 16 that gradually widens in the positive direction of the X-axis. In the example shown in Fig. 1, the angle formed between the normal to the inner surface 16 and the positive direction of the X-axis changes in two stages so that it becomes smaller toward the positive direction of the X-axis. The angle formed between the normal to the inner surface 16 and the positive direction of the X-axis may change in three or more stages, may change continuously, or may remain constant. The angle formed between the normal to the 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 below.

[0045] The second speaker 20 is disposed on the negative X-axis side of the first speaker 10 and outputs a 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. The second sound S2 includes a canceling sound that is out of phase with the first sound S1 and can cancel out the first sound S1. Therefore, at a certain position, the first sound S1 and the second sound S2 overlap, reducing the sound pressure of the combined sound of the first sound S1 and the second sound S2 at that position. The second speaker 20 is composed of, for example, a diaphragm, a magnetic circuit, and a voice coil. 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, with the diaphragm of the second speaker 20 exposed. The diaphragm of the second speaker 20 vibrates in the front-rear direction, and a second sound S2 is output in the negative direction of the X axis.

[0046] The second housing 21 is a cylindrical housing whose axis is in the positive direction of the X axis. The second housing 21 is connected to the end of the first housing 11 on the negative side of the X axis. The first housing 11 and the second housing 21 may be connected via a connecting member. The second housing 21 has an internal space that houses the second speaker 20 and is also referred to as a speaker cabinet or 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 negative side of the X axis, and the opening is closed by the second speaker 20. The end of the second housing 21 on the positive side of the X axis is closed by a plate-shaped member. When viewed from the positive side of the X axis, the center of the second speaker 20 and the center of the second housing 21 coincide with each other. No through-holes are formed in the side walls of the second housing 21.

[0047] The diffuser 23 is a member that diffuses the second sound S2 output from the second speaker 20. Because the second sound S2 is diffused by the diffuser 23, it is possible to widen the range in which the second sound S2 cancels out the first sound S1. It is also possible to prevent the sound pressure of the second sound S2 from increasing in a specific location.

[0048] The diffuser 23 is disposed on the output side of the second speaker 20 from which the second sound S2 is output, i.e., on the negative X-axis side of the second speaker 20, so as to face the second speaker 20. The diffuser 23 is fixed to the end of the third housing 31 on the positive X-axis side. In the example shown in Fig. 1 , the diffuser 23 has a conical portion that protrudes toward the second speaker 20. There are no particular limitations on the shape of the diffuser 23 as long as it can diffuse the second sound S2.

[0049] The substrate 30 is a substrate on which a signal processing circuit 50 (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 circuit board 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 third housing 31 has a frustum shape, but it may also have a cylindrical or rectangular prism shape. Although not shown, an attachment member for attaching the speaker device 1 to a ceiling or the like may be provided on the end of the third housing 31 on the negative X-axis direction side. The orientation in which the speaker device 1 is attached is not particularly limited. For example, the speaker device 1 may be hung from the ceiling directly or via a rail or the like 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 substrate 30 shown in FIG.

[0052] The signal processing circuit 50 performs signal processing on a 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 audio signal output device 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 signal processing circuit 50 may also receive the first audio signal based on audio data stored in a memory 61.

[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) phase and amplitude control coefficients for each frequency to the input signal and output the result. The filter characteristics of the first FIR filter 51 and the second FIR filter 52 are determined, for example, by 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 of the first audio signal in a frequency band lower than the cutoff frequency. The cutoff frequency of the low-pass filter 53 is, for example, 1 kHz to 5 kHz. The cutoff frequency of the low-pass filter 53 may be 2 kHz to 4 kHz. By inputting the first audio signal to the low-pass filter 53, it is possible to reduce the amount of processing in subsequent stages. Furthermore, 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-frequency range, and even if the first sound S1 is blocked by the low-pass filter 53, the effect on the directionality 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 that have frequencies higher than the cutoff frequency. The cutoff frequency of the high-pass filter 54 is set to 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 together, and outputs the resulting 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 together in an adder 55 to generate the first output signal OUT1. That is, the first output signal OUT1 is the output of the adder 55. Furthermore, 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 includes, 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 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 formed of, for example, 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 an external device 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, if 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 the external device such as the information processing device 100 via the communication interface 63. The communication via the communication interface 63 may be wireless communication or wired communication. There is no particular limitation on the communication standard for the communication via the communication interface 63. Note that the speaker device 1 does not need to be constantly connected to the external device such as the information processing device 100, and may be connected to the 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 below.

[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, a user interface, etc. The information processing device 100 determines the filter characteristics of the first FIR filter 51 and the second FIR filter 52 by causing the processor to execute 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 First FIR Filter and Second 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. 3 and 4. FIG.

[0066] 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] When the first speaker 10 emits the first sound S1 and the second speaker 20 emits the second sound S2, the first sound S1 and the second sound S2 overlap at the first position P1 and the second position P2, and the sound output from 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 from 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 decreases by a predetermined value or more relative to the sound pressure of the sound based on the first audio signal at the first position P1 due to the overlap of the first sound S1 and the second sound S2. 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 directly in front of the first speaker 10 in the positive X-axis direction. The second position P2 is located in a direction that forms a predetermined angle θ with respect to the positive X-axis direction 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 offset 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. Furthermore, 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. Specifically, the center of the tip of the first horn 15 is the intersection of a line that passes through the center of the first speaker 10 and is parallel to the positive X-axis direction and includes the tip of the first horn 15, and a plane that is perpendicular to the positive X-axis direction and includes the tip of the first horn 15. The predetermined angle θ is, for example, 60 degrees, but is set depending on the angular range of the directivity of the speaker device 1. The predetermined angle θ is, for example, not less than 30 degrees and not more than 180 degrees. The predetermined angle θ may be not less than 45 degrees and not more than 120 degrees. 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 circles is, for example, not less than 0.5 m and not more than 2 m.

[0070] The filter characteristics of the first FIR filter 51 and the second FIR filter 52 are set so that a composite sound of the first sound S1 and the second sound S2 based on the first audio signal has desired amplitude-frequency characteristics at the first position P1 and the second position P2, respectively. 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. Furthermore, 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. This makes it possible to compensate for the sound pressure in the low frequency range of the synthesized sound, which may be reduced due to the overlap of the first sound S1 and the second sound S2 at the first position P1.

[0071] 3 and 4, a method by 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. Fig. 4 shows a process by 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, 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 via 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 test sounds based on the test audio signal are output from the first speaker 10 and the second speaker 20. At this time, 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 transmitted from the speaker device 1 is picked up 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 picked up 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 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 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 characteristics of the target test sound at the first position P1 are set to be the same as the amplitude-frequency characteristics of the test audio signal to be transmitted. Furthermore, for example, the amplitude-frequency characteristics of the target test sound at the second position P2 are set to be lower than the amplitude-frequency characteristics of the target test sound at the first position P1 by a predetermined sound pressure. The average value of the predetermined sound pressure in the frequency range for which the adaptive filter is designed is, for example, 10 dB or more and 30 dB or less. Note that these amplitude-frequency characteristics of the target test sound at the first position P1 and the second position P2 are merely examples, and ideal amplitude-frequency characteristics at the first position P1 and the second position P2 are set depending on the acoustic design, etc.

[0075] Next, the information processing device 100 determines whether a termination condition for the adaptive filter design is satisfied (step S14). The termination condition is, for example, whether the difference between the amplitude-frequency characteristics of the acquired test sounds at the first position P1 and the second position P2 and the amplitude-frequency characteristics of the target test sounds for each position P2 is equal to or less 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 processing from step S11 again using the filter characteristics of the first FIR filter 51 and the second FIR filter 52 determined above. By repeating the processing from step S11 to step S13, the filter characteristics of the first FIR filter 51 and the second FIR filter 52 are designed so that the amplitude-frequency characteristics of the target test sound 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 less 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 termination condition is satisfied when a predetermined time (number of times) has elapsed.

[0079] Through 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 reduced 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 effects of the speaker device 1 will be described. With the configuration described above, the speaker device 1 can obtain directivity for sounds over a wide frequency range. This will be described with reference to FIG. 5 . FIG. 5 is a diagram illustrating the effects of the speaker device 1. In FIG. 5 , the vertical axis represents the difference in sound pressure of the sound based on the first audio signal at the second position P2 relative to the sound pressure of the sound based on the first audio signal at the first position P1. That is, as the vertical axis in FIG. 5 becomes more negative, the sound pressure of the sound based on the first audio signal at the second position P2 decreases compared to the sound pressure of the sound based on the first audio signal at the first position P1, indicating higher directivity. In FIG. 5 , the horizontal axis represents frequency. In FIG. 5 , region A1 schematically represents the contribution to directivity of the first horn 15. In FIG. 5 , region A2 schematically represents the contribution to directivity of the second sound S2 from the second speaker 20 canceling out the first sound S1. 5, an area A3 schematically shows the contribution to directivity of the plurality of through holes 12. Note that the contribution to directivity shown by areas A1 to A3 is a schematic example, and the size of the areas, the frequency range, etc. are not limited to those shown in FIG.

[0082] The first sound S1 output from the first speaker 10 has its tendency to travel in a straight line in the positive direction of the X axis enhanced by the first horn 15. The first horn 15 mainly enhances the directivity in the high frequency range of 3 kHz or higher, which has a tendency to travel in a straight line. On the other hand, the lower the frequency of the sound, the less the straight line it travels, and therefore the contribution of the first horn 15 to the directivity also decreases, as shown in area A1. Increasing the size of the first horn 15 can also improve the straight line of sounds with relatively low frequencies, but this is disadvantageous for miniaturizing the speaker device 1.

[0083] Furthermore, 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 reduced by a predetermined value or more relative to the sound pressure of the sound based on the first audio signal at the first position P1. 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 overlaps with the first sound S1 at the second position P2 to cancel out the first sound S1. The lower the frequency, the easier it is to achieve a phase difference that cancels out the sounds caused by the overlapping of the first sound S1 and the second sound S2, and so the directivity is mainly increased in the low-frequency range of 1 kHz or less. Furthermore, because the first FIR filter 51 and the second FIR filter 52 adjust the phase and amplitude of the first sound S1 and the second sound S2 for each frequency, 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, for example, in the frequency range of 1 kHz to 3 kHz, and the directivity can be increased.

[0084] In this way, by increasing the linearity of high-frequency sounds with the first horn 15 and canceling out the first sound S1 with the second sound S2, it is possible to obtain directionality for sounds in a wide frequency range with the speaker device 1. Furthermore, since the directionality for mid- and low-frequency sounds can be increased without increasing the size of the first horn 15, it is possible to make the speaker device 1 more compact.

[0085] Furthermore, as the diaphragm vibrates, the first speaker 10 outputs a first sound S1 in the positive direction of the X-axis and also outputs a sound of opposite phase to the first sound S1 into the internal space of the first housing 11. Because multiple through-holes 12 are formed in the sidewall of the first housing 11, the sound of opposite phase to the first sound S1 output into the internal space of the first housing 11 is output to the outside of the first housing 11 through the multiple through-holes 12. Part of the first sound S1 that veers around in the left, right, up, and down directions after leaving the first horn 15 is canceled out by the sound output from the multiple through-holes 12. Therefore, as shown in area A3, the multiple through-holes 12 enhance directivity in the low-frequency range below 1 kHz, where veeraround is particularly likely to occur. Therefore, at frequencies where the first horn 15 makes little contribution to directivity, the sound output from the multiple through-holes 12 cancels out the first sound S1, thereby enhancing directivity.

[0086] Next, measurement results of the directivity of sound output 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 sound output from a speaker device according to a comparative example. FIG. 7 is a graph showing an example of the directivity of sound output from the speaker device 1 according to the present embodiment. FIGS. 6 and 7 show sound pressures (unit: dB) based on the sound pressure at the first position P1. Also, FIGS. 6 and 7 show sound pressures of 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. Furthermore, in the speaker device according to the comparative example, a second sound S2 based on a 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 predetermined angle θ is 60 degrees.

[0087] As shown in Figure 6, the direction in which the sound pressure decreases varies depending on the frequency of the sound output from the speaker device according to the comparative example. Furthermore, for some 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 is unable to improve the directivity for sounds over a wide frequency range. Furthermore, for 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 made uniform, and for some 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 at any frequency is low in the direction forming an angle of 60 degrees with respect to the positive direction of the X-axis. In other words, the speaker device 1 according to the present embodiment can enhance the directivity for sounds in a wide frequency range. Furthermore, 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, thereby realizing narrow directivity.

[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 multiple through holes 12 are formed in the first housing 11, thereby enabling the speaker device 1 to have increased 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 that the second sound S2 cancels out the first sound S1 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 that is opposite to the positive X-axis direction in which the first speaker 10 outputs the first sound S1. This allows 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 to be increased while preventing the overall size of the speaker device 1 from increasing.

[0091] [Modification 1] Next, a description will be given of Modification 1 of the embodiment. In the following description of Modification 1, 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 as viewed from above (the positive Z-axis direction). For ease of explanation, FIG. 8 illustrates a cross section of the first horn 15 and the second horn 25 cut in half along the XY plane. In reality, the remaining halves of the first horn 15 and the second horn 25 are located on the near side of the page in FIG. 8 (the positive Z-axis direction). In FIG. 8 , the first speaker 10, the second speaker 20, and the circuit board 30 housed in the first housing 11, the second housing 21, and the third housing 31, respectively, are indicated by dashed lines. In FIG. 8 , sound output from the second speaker 20 is schematically indicated 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 it further includes a second horn 25 .

[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 arranged to surround the second speaker 20 and the diffuser 23. When viewed from the positive side of the X axis, the centers of the second speaker 20, the second horn 25, and the diffuser 23 are aligned. The second horn 25 is cylindrical and opens in the positive and negative directions of the X axis (in other words, the front-to-rear direction). The second horn 25 is attached to the end of the third housing 31 on the positive side of the X axis so as to surround the space on the positive side of the X axis of the diffuser 23. The opening of the second horn 25 on the negative X-axis direction side is blocked by the diffuser 23 and the third housing 31, and the opening of the second horn 25 on the positive X-axis direction side is open. The axial direction of the second horn 25 coincides with the positive X-axis direction. When viewed from the positive X-axis direction, the second horn 25 extends further outward than the first horn 15.

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

[0096] The shape of second horn 25 is not limited to a cylindrical shape, but 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 of third housing 31 on the positive side of the X axis so that the opening is covered by diffuser 23 and third housing 31, for example.

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

[0098] Furthermore, without the second horn 25, the second sound S2 travels directly toward the negative X-axis direction of the speaker device 2, increasing the path difference between the first sound S1 and the second sound S2 traveling toward the negative X-axis direction of the speaker device 2, making it difficult for the second sound S2 to cancel out the first sound S1 on the negative X-axis direction of the speaker device 2. In contrast, with the presence of the second horn 25, the path of the second sound S2 traveling toward the negative X-axis direction of the speaker device 2 is lengthened, making the path difference between the first sound S1 and the second sound S2 traveling toward the negative X-axis direction of the speaker device 2 smaller than when the second horn 25 is not present. Therefore, the first sound S1 is more likely to be canceled out by the second sound S2 even on the negative X-axis direction of the speaker device 2.

[0099] Although the second speaker 20 of the speaker device 2 outputs the second sound S2 in the negative direction of the X axis, 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 as viewed from above (the positive direction of the Z axis). Note that for the sake of explanation, FIG. 9 shows a cross section of the first horn 15 and the second horn 25 cut in half along the XY plane. In reality, the other halves of the first horn 15 and the second horn 25 are located on the front side of the page in FIG. 9 (the positive direction of the Z axis). In FIG. 9, the first speaker 10, the second speaker 20, and the circuit board 30 housed in the first housing 11, the second housing 21, and the third housing 31, respectively, are indicated 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 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] In the speaker device 2A, the second housing 21 is connected to the end of the first housing 11 on the negative X-axis direction side via a connecting member 32. An opening in which the second speaker 20 is installed is provided at the end of the second housing 21 on the positive X-axis direction side, and this opening is closed by the second speaker 20. In addition, the end of the second housing 21 on the negative X-axis direction side is closed 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 emitted, that is, on the positive side of the X-axis from the second speaker 20, and facing the second speaker 20. The diffuser 23 is fixed to the 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, has openings 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] The speaker device 2A also has the second horn 25, so that the same effect as that of 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] [Modification 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 it includes a signal processing circuit 350 having a configuration in which an adder 56 is further added to the signal processing circuit 50, instead of 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 variant 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 the masking sound. The masking sound is a sound unrelated to the first audio signal, such as an environmental sound such as the sound of a river. For example, audio data of the masking sound is stored in the memory 61, and the processor 60 generates the 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 an external device may be input to the adder 56 via the input interface. Note that 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. Therefore, the second sound S2 based on the second output signal OUT2 includes not only a canceling sound that cancels out the first sound S1, but also a masking sound that is unrelated to the sound desired to be heard by the speaker device 3. At the second position P2, the sound pressure of the sound based on the first audio signal is lower than at the first position P1, but it is difficult to reduce the sound pressure to 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 is bothersome to 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 less audible at the second position P2, even when the speaker device 3 is installed in a quiet environment.

[0112] [Modification 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 in detail below. As will be described in detail below, the sound-absorbing material absorbs sound, thereby reducing the sound pressure on the negative X-axis side of the speaker device, where the first sound S1 is less likely to be canceled out by the second sound S2, and further improving the directivity.

[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 (the positive direction of the Z axis). Note that, 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. In reality, the remaining halves of the first horn 15, the sound absorbing material 70, and the sound reflecting material 71 are located on the front side of the paper in Fig. 11 (the positive direction of the Z axis). 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 that surrounds 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 external 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 two surfaces facing each other in the thickness direction of the sound-absorbing material 70: 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 relative to the first surface 70a. 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 portion 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 a 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 the 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 positioned within 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, the angle between a first angle α1 formed between the extension direction of the first surface 70a and the positive X-axis direction in a cross-sectional view on a plane parallel to the positive X-axis direction passing through the center of the first speaker 10, and a second angle α2 formed between the 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. This reduces the sound pressure of sound directed along the sound-absorbing material 70, making it less likely for sound to bend toward the negative X-axis direction, effectively reducing the sound pressure of sound on the negative X-axis side of the sound-absorbing material 70. Furthermore, 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. 11 , for the sake of explanation, the arrows indicating the positive X-axis direction (D1 in the figure), which is the direction 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 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. Furthermore, the phrase "the predetermined angle θ is an angle between the first angle α1 and the second angle α2" includes cases in which the predetermined angle θ is the same as the first angle α1 and the second angle α2. The predetermined angle θ may be the same 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 from the speaker device 4 from being disturbed when part of the sound emitted from the speaker device 4 is reflected by the sound-absorbing material 70 and the sound-reflecting material 71. The first angle α1 may be an angle other than 90 degrees, and may be, for example, between 45 degrees and 135 degrees.

[0125] The sound-absorbing material constituting the sound-absorbing material 70 is not particularly limited, but may include, for example, a Helmholtz resonator or a foam having open cells such as a sponge. The sound-absorbing material 70 may also be a composite material containing multiple types of sound-absorbing materials. For example, the sound-absorbing material 70 may be formed by laminating a plate-shaped Helmholtz resonator and a plate-shaped foam. By including a Helmholtz resonator in the sound-absorbing material 70, it is possible to absorb mid- and low-frequency sounds, the directionality of which is difficult to increase using 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 side of the speaker device 4, thereby improving the directivity.

[0127] The sound reflecting material 71 is disposed on the negative X-axis side of the sound absorbing material 70. The sound reflecting material 71 is provided on the second surface 70b of the sound absorbing material 70. When viewed from the positive X-axis side, the outline of the sound reflecting material 71 coincides with, for example, the outline of the sound absorbing material 70. When viewed from the positive X-axis side, 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 positioned within 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 emitted from the speaker device 4 will be described.

[0131] 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 70 and the sound reflecting material 71 are removed from the speaker device 4 according to this modified example. FIG. 13 is a graph showing an example of the directivity of sound emitted from the speaker device 4 according to this modified example. FIGS. 12 and 13 show sound pressures (unit: dB) based on the sound pressure at the first position P1. Also, FIGS. 12 and 13 show sound pressures of sounds of 300 Hz, 500 Hz, 2 kHz, and 8 kHz. In the speaker device used for the sound measurement shown in FIG. 12, the predetermined angle θ is 90 degrees. In the speaker device 4 used for the sound measurement shown in FIG. 13, the 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 the sound-absorbing material 70 and the sound-reflecting material 71, the sound pressure of sounds of all frequencies is low in directions that form an angle of 90 degrees with respect to the positive direction of the X-axis relative to the first speaker 10, and the directionality can be improved for sounds over a wide frequency range compared to the speaker device according to the comparative example shown in FIG. 6 above.

[0133] As shown in FIG. 13 , the sound emitted 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. First, the sound absorbing material 70 absorbs the first sound S1 and the second sound S2 traveling in the negative X-axis direction. Second, the predetermined angle θ is 90 degrees, the same as the first angle α1, so that the sound pressure of the sound traveling along the sound absorbing material 70 is lower, making it less likely for the sound to bend in the negative X-axis direction. Third, 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 transmitted in the positive direction of the X axis 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 but are reflected by the sound-reflecting material 71 overlap with the characteristics of the sound transmitted in the positive direction of the X axis.

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

[0136] The positions at which 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 appearances of 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 Fig. 16 ), the sound-absorbing material 70, and the sound-reflecting material 71 cut in half along the XY plane. In reality, the remaining halves of the first horn 15, the second horn 25 (only in Fig. 16 ), the sound-absorbing material 70, and the sound-reflecting material 71 are located on the front side of the paper (the positive Z-axis direction) in Figs. 14 to 16 . Furthermore, 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 indicated by dashed lines.

[0137] 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 positive X-axis 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 negative X-axis side of the sound output position of the second speaker 20. In addition, in the speaker device 4A, when viewed from the positive X-axis side, a gap is provided between the second housing 21 and the sound-absorbing material 70 to allow the second sound S2 to travel in the positive X-axis 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) 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] 16 includes a second horn 25, and a sound-absorbing material 70 is attached to the second horn 25. That is, the speaker device 4C has a configuration in which a sound-absorbing material 70 and a 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 extends outward from the second horn 25. Note that the sound-absorbing material 70 may be attached to the second horn 25 via the sound-reflecting material 71. The sound-absorbing material 70 may be attached to a location other than the end of the second horn 25, or may be attached to a mounting location such as the ceiling or wall on which the second housing 21, the third housing 31, or the speaker device 4C is mounted, instead of the second horn 25.

[0140] In addition, in the speaker device 4C, at least a portion 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 the above examples, the sound-absorbing material 70 and the sound-reflecting material 71 are described as being installed in a configuration in which the second horn 25 is removed from the speaker device 2A, or in the configuration of the speaker device 2A, but they may also be installed in any of the speaker devices 1, 2, and 3 described above.

[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 made as appropriate. Furthermore, it is also possible to combine the components described in the above embodiments to create new embodiments.

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

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

[0145] Furthermore, for example, in the above embodiment, the filter characteristics of the first FIR filter 51 and the second FIR filter 52 are determined by 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] Furthermore, for example, in the above-described embodiment, the signal processing circuits 50 and 350 include 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 embodiments, the processes 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 program may be executed by a single processor or multiple processors. In other words, centralized processing or distributed processing may be performed.

[0148] Furthermore, the general or specific aspects of the present disclosure may be realized as a system, device, method, integrated circuit, computer program, or computer-readable recording medium such as a CD-ROM. Also, the present disclosure may be realized as any combination of a system, device, method, integrated circuit, computer program, and 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 as a single device. Furthermore, when the speaker system is realized by multiple devices, the components of the speaker system may be distributed among the multiple devices in any manner.

[0149] In addition, this disclosure also includes forms obtained by making various modifications to the embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions of the embodiments within the scope that does not deviate from the intent of this disclosure.

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

[0151] 1, 2, 2A, 3, 4, 4A, 4B, 4C Speaker device 10 First speaker 11 First housing 12 Through hole 15 First horn 16, 26 Inner surface 20 Second speaker 21 Second housing 23 Diffuser 25 Second horn 30 Substrate 31 Third housing 32 Connecting member 50, 350 Signal processing circuit 51 First FIR filter 52 Second FIR filter 53 Low-pass filter 54 High-pass filter 55, 56 Adder 60 Processor 61 Memory 62 Input interface 63 Communication interface 70 Sound absorbing material 70a First surface 70b Second surface 71 Sound reflecting material 100 Information processing device 111, 112 Microphone OUT1 First output signal OUT2 Second output signal P1 First position P2 2nd position S1 1st sound S2 2nd sound

Claims

1. A signal processing circuit that performs signal processing on an input first audio signal and generates 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 the 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, wherein the signal processing circuit has 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, the first output signal is generated based on the output of the first filter, and the second output signal is generated based on the output of the second filter, a first filter and a second filter having filter characteristics that adjust a phase and an amplitude for each frequency of a signal of at least a part of a frequency band of the first audio signal so 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, relative to a sound pressure of a sound based on the first audio signal at a 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.

2. The speaker device according to claim 1, 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 an output of the low-pass filter.

3. A speaker device as described in claim 1 or 2, comprising a cylindrical housing whose axial direction is the first direction, the first speaker being provided at an end of the housing on the first direction side, and a plurality of through holes being formed in a circumferential side wall of the housing.

4. The speaker device according to claim 1 or 2, wherein the second speaker outputs the second sound in the second direction.

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

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

7. The speaker device according to claim 1 or 2, wherein 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.

8. A speaker device as described in claim 1 or 2, comprising 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 specified 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 the end of the surface and the first direction in the cross-sectional view.

9. The speaker device according to claim 8, further comprising a plate-shaped sound reflecting material arranged on the second direction side of the sound absorbing material.

10. The speaker device according to claim 8, wherein the first angle is 90 degrees.

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