Sound reproduction apparatus, signal processing apparatus, and signal processing method

Abstract

The sound reproduction apparatus according to the present application includes a first microphone for noise cancellation processing performed by a feedback scheme, a second microphone for noise cancellation processing performed by a feedback scheme and having a sound collecting surface in a direction different from that of the sound collecting surface of the first microphone, and an acoustic signal processing unit which generates a noise cancellation signal using a first sound collecting signal obtained by sound collection by the first microphone and a second sound collecting signal obtained by sound collection by the second microphone.

Description

Technical Field

[0001] This disclosure relates to an audio reproduction apparatus, a signal processing apparatus, and a signal processing method. In particular, this disclosure relates to the generation of a noise cancellation signal. Background Technology

[0002] As disclosed in the following patent documents 1, 2 and 3, a noise cancellation system is known that reduces noise in the external environment in headphones or earphones used in portable audio players, etc., and provides the listener with a well-reproduced sound field space with reduced external noise.

[0003] Citation List

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-122729

[0006] Patent Document 2: Japanese Patent Application Publication No. 2008-116782

[0007] Patent Document 3: Japanese Patent Application Publication No. 2008-250270 Summary of the Invention

[0008] The problem to be solved by the present invention

[0009] An example of this type of noise cancellation system is an active noise reduction system that performs active noise reduction and basically has the following configuration.

[0010] In other words, external noise (noise) is collected by a microphone, which acts as a sound-to-electric conversion device, and a noise cancellation signal that is acoustically out of phase with the noise is generated from the acoustic signal of the collected noise. The noise cancellation signal is then combined with the acoustic signal of the original listening object, such as music, and the sound is acoustically reproduced through a loudspeaker. As a result, the external noise is acoustically cancelled, thereby reducing noise.

[0011] In such a noise reduction system, it is believed that noise cancellation performance can be improved by using multiple microphones to collect sound and generating a noise cancellation signal through appropriate filtering.

[0012] In this disclosure, assuming the use of multiple microphones as described above, a more suitable microphone arrangement is proposed.

[0013] Solutions to the problem

[0014] The sound reproduction apparatus according to this disclosure includes: a first microphone for noise cancellation processing using a feedback scheme; a second microphone including a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone, and for noise cancellation processing using a feedback scheme; and an audio signal processing unit configured to generate a noise cancellation signal using a first sound collection signal collected by the first microphone and a second sound collection signal collected by the second microphone.

[0015] In a configuration that includes multiple microphones for noise cancellation processing using a feedback scheme, it is easy to collect sound in multiple acoustic spaces within the sound reproduction device.

[0016] In the aforementioned audio reproduction device, the sound collection surface of the first microphone can be located closer to the driver unit configured to perform audio output based on a noise cancellation signal, compared to the sound collection surface of the second microphone.

[0017] This makes it unlikely that the transfer function of the space from the driver unit to the sound collection surface of the first microphone will change.

[0018] In the aforementioned audio reproduction device, the sound collection surface of the first microphone can be located in the direction of sound emission of the driver unit configured to perform audio output based on a noise cancellation signal.

[0019] This makes it unlikely that the transfer function of the space from the driver unit to the sound collection surface of the first microphone will change.

[0020] The aforementioned sound reproduction device may further include a housing in which a driver unit configured to perform sound output based on a noise cancellation signal is disposed, and has a sound output outlet through which output sound from the driver unit is emitted, wherein the first microphone and the second microphone may be disposed in the housing, and the second microphone may be located closer to the sound output outlet than the first microphone.

[0021] As a result, the second microphone can collect sound at a location closer to the eardrum than the first microphone.

[0022] In the aforementioned audio reproduction device, the sound collecting surface of the second microphone may be located in a position not facing the sound emission direction of the driver unit configured to perform audio output based on the noise cancellation signal.

[0023] This makes it easier for the second microphone to collect noise.

[0024] In the aforementioned sound reproduction device, at least one acoustic space in the housing may be located in the sound emission direction of the driver unit, and the first microphone and the second microphone may be located in one acoustic space.

[0025] As a result, noise components in the acoustic space where the microphone is placed can be collected with high precision.

[0026] In the aforementioned sound reproduction device, the first microphone can be positioned such that its sound collecting surface faces the sound emission direction of the driver unit, and the second microphone can be positioned such that its sound collecting surface faces the same direction as the sound emission direction of the driver unit.

[0027] As a result, the spatial transfer function from the driver unit to the sound collection surface of the first microphone is unlikely to change. Furthermore, the second microphone can easily collect noise at a location closer to the eardrum.

[0028] In the aforementioned sound reproduction device, the first microphone and the second microphone can be placed in different sound spaces.

[0029] This causes the noise collected by the first microphone to be different from the noise collected by the second microphone.

[0030] In the aforementioned sound reproduction device, multiple sound spaces can be provided in the housing, and the first microphone and the second microphone can be located in different spaces among the multiple sound spaces.

[0031] This makes the noise collected by the first microphone even more different from the noise collected by the second microphone.

[0032] In the aforementioned sound reproduction device, an acoustic damping component can be installed to separate the first acoustic space where the first microphone is located from the second acoustic space where the second microphone is located.

[0033] This allows for a stable space, where, for an acoustic space, the transfer function of the space from the driver unit to the microphone is unlikely to change.

[0034] The aforementioned sound reproduction device may further include a housing in which a driver unit configured to perform sound output based on a noise cancellation signal is disposed, and has a sound output outlet through which output sound from the driver unit is emitted, wherein the first sound space may be a space surrounded by the driver unit, the acoustic damping member and the housing, and the second sound space may be a space surrounded by the acoustic damping member, the housing and the sound output outlet.

[0035] As a result, the first acoustic space becomes a stable space, in which the transfer function is unlikely to change. Furthermore, the second acoustic space becomes a space where noise from locations closer to the eardrum is easily collected.

[0036] In the aforementioned sound reproduction device, the first microphone may be located in front of the sound emission direction of the driver unit that performs sound output based on the noise cancellation signal, and the second microphone may be located behind the driver unit.

[0037] Therefore, the second microphone located behind the driver unit can collect sound with a phase opposite to the audio output. Furthermore, the transfer function of the space from the driver unit to the sound collection surface of the second microphone is designed to be unlikely to change with the listener's wearing posture.

[0038] The aforementioned sound reproduction device may further include: a first feedback filter configured to generate a first noise cancellation signal based on the high-frequency component of the first sound collection signal; and a second feedback filter configured to generate a second noise cancellation signal based on the low-frequency component of the second sound collection signal, wherein the sound signal processing unit may generate the noise cancellation signal based on the first noise cancellation signal and the second noise cancellation signal.

[0039] The first microphone is positioned closer to the driver unit than the second microphone, so the filter coefficients set for the first FB filter are less likely to be inappropriate than those set for the second FB filter. This makes the noise cancellation signal based on the first sound collection signal less likely to cause feedback than the noise cancellation signal based on the second sound collection signal.

[0040] In the aforementioned sound reproduction device, the high-frequency component of the first sound collection signal can be extracted by a high-pass filter, a high-shelf filter, or a high-peak EQ filter, and the low-frequency component of the second sound collection signal can be extracted by a low-pass filter, a low-shelf filter, or a low-peak EQ filter.

[0041] As a result, the high-frequency component of the sound signal, which is more likely to cause feedback, can be input into the feedback loop of the first microphone, where the spatial transfer function from the driver unit to the microphone is unlikely to change. Furthermore, the low-frequency component of the sound signal can be input into the feedback loop of the second microphone, which is more likely to collect noise closer to the eardrum.

[0042] The aforementioned audio reproduction device may further include: a third microphone for noise cancellation processing using a feedforward scheme, wherein the audio signal processing unit may generate a noise cancellation signal by using a first sound collection signal, a second sound collection signal, and a third sound collection signal collected by the third microphone.

[0043] For example, one could envision setting up a third microphone to collect sound from outside the audio reproduction device.

[0044] The signal processing apparatus according to this disclosure includes an audio signal processing unit configured to generate a noise cancellation signal using a first sound collection signal collected by a first microphone for noise cancellation processing using a feedback scheme and a second sound collection signal collected by a second microphone, the second microphone including a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone, and for noise cancellation processing using a feedback scheme.

[0045] The signal processing method according to this disclosure includes generating a noise cancellation signal using a first sound collection signal collected by a first microphone for noise cancellation processing using a feedback scheme and a second sound collection signal collected by a second microphone, the second microphone including a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone, and for noise cancellation processing using a feedback scheme.

[0046] According to the signal processing device and signal processing method, in a configuration including multiple microphones for noise cancellation processing using a feedback scheme, sound can be easily collected in multiple acoustic spaces in the sound reproduction device. Attached Figure Description

[0047] Figure 1 This is a block diagram illustrating an example configuration of an acoustic reproduction device that applies a noise cancellation system using a feedback scheme, from the perspective of the transfer function.

[0048] Figure 2 This is a diagram showing the headphones of the first embodiment.

[0049] Figure 3 This is a block diagram of the sound reproduction device according to the first embodiment.

[0050] Figure 4 This is a block diagram of the first DSP in the first embodiment.

[0051] Figure 5 This is a block diagram of the second DSP in the first embodiment.

[0052] Figure 6 This is a diagram illustrating a headset according to a first embodiment.

[0053] Figure 7 This is a diagram showing the headphones according to the second embodiment.

[0054] Figure 8 This is a diagram illustrating a second embodiment of the headset.

[0055] Figure 9 This is a diagram showing the headphones according to the third embodiment.

[0056] Figure 10 This is a diagram illustrating a third embodiment of the headset.

[0057] Figure 11 This is a diagram showing the headphones according to the fourth embodiment.

[0058] Figure 12 This is a block diagram of an audio reproduction device according to the fourth embodiment.

[0059] Figure 13 This is a block diagram of the third DSP in the fourth embodiment.

[0060] Figure 14 This is a block diagram of the first modified sound reproduction device.

[0061] Figure 15 This is a diagram showing an example of attaching an acoustic damping component.

[0062] Figure 16 This is a diagram showing an example of attaching an acoustic damping component.

[0063] Figure 17 This is a diagram showing an example of attaching an acoustic damping component.

[0064] Figure 18 This is a diagram showing an example of attaching an acoustic damping component.

[0065] Figure 19 This is a graph showing the frequency characteristics of each filter. Detailed Implementation

[0066] The embodiments will be described below in the following order.

[0067] <1. Description of noise cancellation technology>

[0068] <2. First Embodiment>

[0069] <2-1. Configuration of the Sound Reproduction Device>

[0070] <2-2. Internal Configuration of the Sound Reproduction Device>

[0071] <2-3. Sound reproduction device as a headphone>

[0072] <3. Second Embodiment>

[0073] <3-1. As an audio reproduction device for headphones>

[0074] <3-2. Sound reproduction device as a headphone>

[0075] <4. Third Embodiment>

[0076] <4-1. As an audio reproduction device for headphones>

[0077] <4-2. Sound reproduction device as a headphone>

[0078] <5. Fourth Embodiment>

[0079] <5-1. Configuration of the Sound Reproduction Device>

[0080] <5-2. Internal Configuration of the Sound Reproduction Device>

[0081] <6. Revision>

[0082] <6-1. First Revision>

[0083] <6-2. Second Revision>

[0084] <6-3. Other>

[0085] <7. Conclusion>

[0086] <8. This technology>

[0087] Note that the sound reproduction device described in the embodiments and defined in the claims refers to a device worn on the ears of a listener, including not only headband-type devices (headphones) worn on the head, but also types called "earphones" worn on the auricle or ear canal.

[0088] <1. Description of Noise Cancellation Technology>

[0089] This section will describe noise cancellation techniques that utilize feedback schemes. Figure 1 This is a block diagram illustrating an example configuration of an acoustic reproduction device that applies a noise cancellation system using a feedback scheme, from the perspective of the transfer function.

[0090] Notice, Figure 1 Only the configuration of the sound reproduction device on one ear side of the listener is shown. The configuration of the sound reproduction device in each of the left and right ears is similar. Figure 1 The configuration in [the system / system].

[0091] The sound reproduction device is equipped with a driver unit that serves as an electroacoustic conversion device for reproducing sound signals as electrical signals.

[0092] Then, the sound source signal Sm, which is the signal of the music or other music that the listener wants to reproduce, is provided as an output audio signal to the power amplifier through an equalizer and adder. The audio signal passed through the power amplifier is provided to the driver unit and reproduced by the audio amplifier, and the reproduced sound is emitted to the listener's ears.

[0093] An equalizer, adder, power amplifier, microphone, microphone amplifier, and feedback (FB) filter for noise cancellation are positioned in the signal transmission path between the input terminal of the input sound source signal Sm and the driver units for the left and right ears.

[0094] In this configuration, a feedback scheme is used to reduce the noise N from outside the sound reproduction device to the listener's listening position within the sound reproduction device, thus allowing for music listening in a favorable environment.

[0095] In a noise cancellation system using a feedback scheme, noise at the sound synthesis location (noise cancellation point Pc) is collected, and a sound reproduction of the noise and sound signal is synthesized at that location. The listener at that location then hears the sound.

[0096] Therefore, the microphone used for noise collection is positioned at a location where it can collect noise from the noise cancellation point Pc inside the housing of the sound reproduction device. The sound at the microphone location is the control point; therefore, considering the noise attenuation effect, the noise cancellation point Pc is typically positioned near the ear (i.e., the front surface of the driver unit's diaphragm), and the microphone is positioned at this location.

[0097] Then, a component with a phase opposite to that of the noise collected by the microphone is generated by the FB filter as a noise cancellation signal, and the generated noise cancellation signal is provided to the driver unit for sound reproduction, thereby reducing the noise entering the housing of the sound reproduction device from the outside.

[0098] The analog audio signal collected by the microphone is converted into a digital audio signal by an analog-to-digital converter (ADC) via a microphone amplifier. The digital audio signal is then fed into a digital filter (FB filter) used to generate a feedback noise cancellation signal.

[0099] The digital filter generates a noise cancellation signal with characteristics corresponding to the filter coefficients, which are parameters set to the input digital audio signal.

[0100] The generated noise cancellation signal is provided to the adder.

[0101] As described above, the sound source signal Sm that the listener wants to hear is provided to the adder through an equalizer. The equalizer corrects the sound quality of the input audio signal.

[0102] The output of the equalizer and the noise cancellation signal from the FB filter are combined by an adder and supplied as an output audio signal to the driver unit through a power amplifier, where it is reproduced as audio.

[0103] Note that a digital-to-analog converter (DAC) is set up in the stage before or after the adder to convert each signal from a digital signal to an analog signal.

[0104] The reproduced sound includes an acoustic reproduction component generated by the noise cancellation signal produced in the FB filter. The acoustic reproduction component of the noise cancellation signal and the noise are acoustically synthesized, thereby reducing (eliminating) the noise at the noise cancellation point Pc.

[0105] Figure 1 The transfer function for each unit is shown. Specifically, "A" represents the transfer function of the power amplifier, "D" represents the transfer function of the driver unit, "M" represents the transfer function corresponding to the microphone and microphone amplifier section, and "-β" represents the transfer function of the filter designed for feedback. Furthermore, "H" represents the transfer function of the space from the driver unit to the microphone, and "E" represents the transfer function of the equalizer to be applied to the sound source signal Sm for listening purposes. It is assumed that each of the above transfer functions is expressed by a complex number.

[0106] also, Figure 1 In the diagram, "N" represents the noise entering the housing of the audio reproduction device from an external noise source near the microphone location, and "P" represents the sound pressure reaching the listener's ear. Note that possible reasons for external noise being transmitted into the housing of the audio reproduction device may include, for example, external noise leaking as sound pressure from gaps in the ear pad portion, and sound being transmitted into the housing of the audio reproduction device due to the audio reproduction device receiving sound pressure and vibrating.

[0107] Figure 1 The transfer function block in the code can be represented by the following (expression 1).

[0108] (Expression 1)

[0109] P={1 / (1+ADHMβ)}·N+{AHD / (1+ADHMβ)}·ES

[0110] In (Equation 1), focusing on noise, we find that the noise N attenuates to 1 / (1+ADHMβ). However, in order for the system in (Equation 1) to operate stably as a noise cancellation mechanism in the frequency band where noise reduction is desired, the following (Equation 2) needs to be satisfied.

[0111] (Expression 2)

[0112] |1 / (1+ADHMβ)|<1

[0113] Sufficient noise reduction can be achieved by setting the filter coefficients of the FB filter to "-β" that satisfies the above (expression 2).

[0114] <2. First Embodiment>

[0115] <2-1. Configuration of the Sound Reproduction Device>

[0116] Reference Figure 2 A first embodiment of the sound reproduction device 1 is described. Note that... Figure 2 An audio reproduction device 1, which serves as an example, is shown as headphones.

[0117] The sound reproduction device 1 includes a housing 3 forming an internal space 2 and a driver unit 4 arranged in the internal space 2.

[0118] The driver unit 4 includes a diaphragm 4a to enable audio output.

[0119] In the following description, the direction in which the sound is emitted by driver unit 4 will be referred to as "forward".

[0120] The housing 3 includes: a box-shaped portion 5 having a cylindrical shape axial in the front-rear direction and being formed as a box with a front opening; and a tubular sound conduit 6 formed as extending forward from the front opening of the box-shaped portion 5.

[0121] The internal space 2 of the housing 3 includes an arrangement space 7 and a sound guiding space 8. The arrangement space 7 is a space surrounded by a box-shaped portion 5 and each unit, such as the driver unit 4, is placed therein. The sound guiding space 8 is a space surrounded by a sound conduit 6.

[0122] The front opening of the sound duct 6 is configured as a sound outlet 9 for outputting audio output from the driver unit 4 to the outside of the housing 3.

[0123] The actuator unit 4 is, for example, placed at the basic central part in the front-rear direction of the arrangement space 7. The arrangement space 7 is divided by the actuator unit 4 into a front space 7a, which is the space in front of the actuator unit 4, and a rear space 7b, which is the space behind the actuator unit 4.

[0124] For example, the rear space 7b can accommodate a substrate, battery, etc., for driving the driver unit 4.

[0125] In the sound reproduction device 1, a front-detachable earpiece 10 is attached to the outer peripheral surface of the sound outlet 9 in the housing 3. The earpiece 10 is formed of an elastic deformable component such as silicone, rubber, or polyurethane.

[0126] The sound reproduction device 1 includes multiple microphones housed in the interior space 2. Figure 2 This is an example of an audio reproduction device 1 that includes two microphones.

[0127] Specifically, the sound reproduction device 1 includes a first microphone 11 and a second microphone 12 for noise cancellation processing using a feedback scheme.

[0128] The first microphone 11 is positioned in the front space 7a such that the sound collection surface 11a is substantially facing the diaphragm 4a of the driver unit 4.

[0129] The second microphone 12 is positioned in the sound guiding space 8 such that the sound collecting surface 12a faces a different direction than the sound collecting surface 11a of the first microphone 11. Specifically, the second microphone 12 is attached such that the sound collecting surface 12a faces the central axis of the sound duct 6. In other words, the second microphone 12 is positioned so as not to face the diaphragm 4a of the driver unit 4.

[0130] In other words, the first microphone 11 is positioned closer to the driver unit 4 than the second microphone 12.

[0131] In addition, the second microphone 12 is positioned closer to the sound output outlet than the first microphone 11.

[0132] By placing the first microphone 11 and the second microphone 12 in different acoustic spaces, sound can be collected in the front space 7a and the sound guiding space 8, which are different acoustic spaces. In other words, the first sound collection signal S1 of the first microphone 11 is a signal that includes noise in the front space 7a. Furthermore, the second sound collection signal S2 of the second microphone 12 is a signal that includes noise in the sound guiding space 8.

[0133] In addition, the second microphone 12 can collect sound at a position closer to the eardrum than the first microphone 11.

[0134] By adopting the above configuration, feedback control is performed using sound collection signals collected from the first microphone 11 and the second microphone 12 to generate a noise cancellation signal.

[0135] For example, the generated noise cancellation signal is added to the sound source signal Sm to generate an output signal from the driver unit 4. The output signal generated in this way is output from the driver unit 4, so that the listener hears the reproduced sound with reduced noise at a predetermined cancellation point.

[0136] <2-2. Internal Configuration of the Sound Reproduction Device>

[0137] Figure 3 This is a block diagram of the internal configuration of the sound reproduction device 1. Note that... Figure 3 In the accompanying figures, for the sake of simplicity, only one of the left and right channels of the stereo signal is shown. This is achieved by using a similar approach in the other channel. Figure 3 The configuration in the settings allows for noise cancellation processing of stereo sound.

[0138] Please note that the left and right channels can share each component.

[0139] The sound source signal Sm, as a digital signal, is input to the sound reproduction device 1 from an external music / sound source device such as an audio player (not shown). The sound source signal Sm is, for example, a digital signal, such as music that the listener wants to hear.

[0140] The sound reproduction device 1 includes a first amplifier 21A, a first ADC 22A and a first digital signal processor (DSP) 23A, as a unit for performing processing on the first sound collection signal S1 of the first microphone 11.

[0141] In addition, the sound reproduction device 1 includes a second amplifier 21B, a second ADC 22B, and a second DSP 23B as a unit for processing the sound collection signal S2 from the second microphone 12.

[0142] In addition, the audio reproduction device 1 includes adders 24 and 25, equalizer circuit 26, DAC 27 and power amplifier 28.

[0143] As described above, the first sound collection signal S1 is obtained by collecting sound containing noise in the space 7a in front of the diaphragm 4a of the driver unit 4.

[0144] The first sound collection signal S1 is amplified by the first amplifier 21A, converted into a digital signal by the first ADC 22A, and input to the first DSP 23A.

[0145] The first DSP 23A includes a digital filter for generating a feedback noise cancellation signal.

[0146] Figure 4 This is a diagram illustrating a configuration example of the first DSP 23A. As shown, the first DSP 23A includes a high-pass filter (HPF) 31 and a first FB filter 32.

[0147] HPF 31 is a digital filter that removes low-frequency components from the input digital signal from the first ADC 22A.

[0148] The first FB filter 32 is a digital filter used to generate a feedback digital noise cancellation signal.

[0149] In other words, the first FB filter 32 generates a first noise cancellation signal Snc1 based on the high-frequency components in the first sound collection signal S1.

[0150] The signal generated by the first DSP 23A is input to the adder 24.

[0151] As described above, the second sound collection signal S2 is obtained by collecting sound containing noise from the sound guiding space 8, which is the internal space of the sound conduit 6.

[0152] The second sound collection signal S2 is amplified by the second amplifier 21B, converted into a digital signal by the second ADC 22B, and input to the second DSP 23B.

[0153] The second DSP 23B includes a digital filter for generating a feedback noise cancellation signal.

[0154] Figure 5 This is a diagram illustrating a configuration example of the second DSP 23B. As shown, the second DSP 23B includes a low-pass filter (LPF) 33 and a second FB filter 34.

[0155] LPF 33 is a digital filter that removes high-frequency components from the input digital signal from the second ADC 22B.

[0156] The second FB filter 34 is a digital filter used to generate a feedback digital noise cancellation signal.

[0157] In other words, the second FB filter 34 generates the second noise cancellation signal Snc2 based on the low-frequency components in the second sound collection signal S2.

[0158] The signal generated by the second DSP 23B is input to the adder 24.

[0159] Adder 24 adds and synthesizes the first noise cancellation signal Snc1 generated based on the first sound collection signal S1 of the first microphone 11 and the second noise cancellation signal Snc2 generated based on the second sound collection signal S2 of the second microphone 12, and outputs the result as the synthesized noise cancellation signal Snc to adder 25.

[0160] In addition to the synthesized noise cancellation signal Snc, a digital signal based on the sound source signal Sm is also input to the adder 25.

[0161] The sound source signal Sm is input to the equalizer circuit 26.

[0162] The equalizer circuit 26 performs equalization processing on the input sound source signal Sm for sound quality correction and sound quality effect processing, and outputs the obtained digital signal to the adder 25.

[0163] The equalizer circuit 26 can be configured, for example, within a DSP.

[0164] Adder 25 adds and synthesizes the synthesized noise cancellation signal Snc and the signal from equalizer circuit 26, and outputs the result as an output audio signal to DAC 27.

[0165] The output signal from adder 25 is converted into an analog signal by DAC 27, then amplified by power amplifier 28 and provided to driver unit 4.

[0166] In driver unit 4, audio output processing based on the input audio signal is performed. As a result, the listener hears a reproduced sound with reduced noise at a predetermined noise cancellation point.

[0167] like Figure 2 As shown, the first microphone 11 is positioned such that the sound collecting surface 11a faces the diaphragm 4a of the driver unit 4. With this arrangement of the first microphone 11, the transfer function of the space from the driver unit 4 to the first microphone 11 is unlikely to change.

[0168] If the transfer function of the space remains unchanged, the filter coefficients set in the first FB filter 32 can be used to generate a noise-cancelled signal with sufficient noise cancellation performance.

[0169] In other words, the first noise cancellation signal Snc1 generated using the first sound collection signal S1 can fully demonstrate the noise cancellation performance.

[0170] Note that, as Figure 2 As shown, the second microphone 12 is disposed in the sound guiding space 8, and the transfer function of the space from the driver unit 4 to the second microphone 12 may change.

[0171] If the transfer function of the space changes, the filter coefficients set in the second FB filter 34 may be inappropriate, and howling may occur in this case.

[0172] Generally, howling is often caused by high-frequency components equal to or higher than 1 kHz.

[0173] Therefore, for high-frequency components, a first noise cancellation signal Snc1 is generated using a first microphone 11 that utilizes the space transfer function, which is unlikely to change.

[0174] This prevents howling caused by high-frequency components from occurring.

[0175] In addition, for other low-frequency components, a second noise cancellation signal Snc2 is generated using a second microphone 12 that is able to collect sound at a location closer to the listener's eardrum.

[0176] This allows the elimination point to be closer to the eardrum.

[0177] For example, a first noise cancellation signal Snc1 is generated based on the high-frequency component of the first sound collection signal S1 extracted by the HPF 31 with a cutoff frequency of 200Hz.

[0178] Furthermore, a second noise cancellation signal Snc2 is generated based on the low-frequency component of the second sound collection signal S2 extracted from the LPF 33 with a cutoff frequency of 200Hz.

[0179] According to the above configuration, a synthesized noise cancellation signal Snc is generated by synthesizing a first noise cancellation signal Snc1 based on the high-frequency component of the first sound collection signal S1 and a second noise cancellation signal Snc2 based on the low-frequency component of the second sound collection signal S2, so that the noise cancellation performance at the tympanic membrane position can be improved while preventing howling.

[0180] Although Figure 3 An example is shown in which a first DSP 23A and a second DSP 23B are configured, but a digital filter for the first sound collection signal S1 and a digital filter for the second sound collection signal S2 can be formed in one DSP.

[0181] Furthermore, in this case, the equalizer circuit 26 can be formed in the same DSP.

[0182] Note that, although Figure 3 An example is shown where the sound source signal Sm is a digital signal, but the sound source signal Sm can also be an analog signal. In this case, an ADC is used to convert the sound source signal Sm into a digital signal and input it to the equalizer circuit 26.

[0183] The HPF 31 included in the first DSP 23A can be replaced by a shelving filter or a peak equalizer (EQ) filter (see [link]). Figure 19 ).

[0184] Furthermore, the LPF 33 included in the second DSP 23B can be replaced by a low-shelf filter or a low-peak EQ filter (see [link]). Figure 19 ).

[0185] Note that the internal configuration of the sound reproduction device 1 may differ from that of the other devices. Figure 3 , 4 The configuration shown in Figure 5. As an example, at least one of the first FB filter 32 or the second FB filter 34 can be a filter for analog signals. In this case, the first ADC 22A and the second ADC 22B are unnecessary.

[0186] In addition, instead of the first DSP 23A and the second DSP 23B, a central processing unit (CPU), a hardwired circuit that performs hardwired signal processing, etc., can be used.

[0187] Furthermore, the first microphone 11 and the second microphone 12 can be digital microphones. In this case, the first ADC 22A and the second ADC 22B are unnecessary.

[0188] also, Figure 4 The HPF 31 shown may not be located in the stage preceding the first FB filter 32, but rather in the stage following the first FB filter 32. Alternatively, the HPF 31 may be located inside the first FB filter 32.

[0189] Similarly, Figure 5 The LPF 33 shown can be set at the stage after the second FB filter 34, or it can be set inside the second FB filter 34.

[0190] This also applies to subsequent units.

[0191] <2-3. Sound reproduction device as a headphone>

[0192] Reference Figure 6 An example is described of applying the configuration of the first embodiment described above to an audio reproduction device 1A as a headset.

[0193] Note that, with Figure 2 The components shown as the audio reproduction device 1 for headphones will be represented by the same reference numerals.

[0194] The sound reproduction device 1A includes a housing 3 forming an internal space 2 and a driver unit 4 disposed in the internal space 2.

[0195] The driver unit 4 includes a diaphragm 4a to enable audio output.

[0196] The housing 3 includes a base portion 42 and an ear pad 43. The base portion 42 has an arrangement recess 41 to which the driver unit 4 is to be attached, and the ear pad 43 is to be attached to the front peripheral portion of the arrangement recess 41.

[0197] The inner front periphery of the ear pad 43 forms the sound outlet 9.

[0198] The internal space 2 includes: a front space 7a, which is a space surrounded by the ear pad 43, the front surface of the driver unit 4 and the sound outlet 9; and a rear space 7b, which is a space surrounded by the base portion 42 and the rear surface of the driver unit 4.

[0199] The sound reproduction device 1A includes a first microphone 11 and a second microphone 12 for noise cancellation processing using a feedback scheme.

[0200] For example, a protective member 44, which is formed in a mesh shape, is attached to the front of the diaphragm 4a of the driver unit 4 to protect the diaphragm 4a.

[0201] In the protective member 44, the first attachment portion 44a to which the first microphone 11 is to be attached and the second attachment portion 44b to which the second microphone 12 is to be attached are substantially positioned in the center.

[0202] The second microphone 12 is positioned such that the sound collecting surface 12a faces a different direction than the sound collecting surface 11a of the first microphone 11.

[0203] For example, the first attachment portion 44a is made into a recess that opens rearward (in the direction of the diaphragm) and laterally, and the first microphone 11 is attached such that the sound collection surface 11a is substantially facing the diaphragm 4a.

[0204] Furthermore, the second attachment portion 44b is made into a recess that opens forward and laterally, and the second microphone 12 is attached such that the sound collection surface 12a faces the same direction as the sound emission direction of the driver unit 4.

[0205] The first microphone 11 and the second microphone 12 are both located in the front space 7a. In other words, the first microphone 11 and the second microphone 12 are located in the same acoustic space.

[0206] The first microphone 11 and the second microphone 12 are placed in the same acoustic space, and the direction of the sound collecting surface 11a of the first microphone 11 is different from the direction of the sound collecting surface 12a of the second microphone 12, so that noise components can be collected in the acoustic space where the microphones are placed with high precision.

[0207] Therefore, noise cancellation performance can be improved.

[0208] The block diagram of the internal configuration of the sound reproduction device 1A has a similar shape to... Figure 3 The configuration is so specific that its description will be omitted.

[0209] Due to such Figure 3 and 6 The sound reproduction device 1A configured as a headset, as shown, generates a synthesized noise cancellation signal Snc by synthesizing a first noise cancellation signal Snc1 based on the high-frequency component of the first sound collection signal S1 and a second noise cancellation signal Snc2 based on the low-frequency component of the second sound collection signal S2, thereby improving the noise cancellation performance at the tympanic membrane position while preventing feedback.

[0210] <3. Second Embodiment>

[0211] <3-1. As an audio reproduction device for headphones>

[0212] The second embodiment of the sound reproduction device 1B, which is an earphone, includes a sound-resistant member 51 for dividing the internal space 2 into multiple sound spaces.

[0213] Reference Figure 7 Describe the specific configuration. Note that, compared to... Figure 2 The components of the sound reproduction device 1 in the first embodiment shown will be represented by the same reference numerals, and their descriptions will be omitted as appropriate.

[0214] The sound reproduction device 1B includes a housing 3 forming an internal space 2, a driver unit 4 disposed in the internal space 2, a first microphone 11, and a second microphone 12.

[0215] The interior space 2 includes an arrangement space 7 containing each unit and a sound guiding space 8 surrounded by sound conduits 6.

[0216] The arrangement space 7 includes a front space 7a, which is the space in front of the driver unit 4, and a rear space 7b, which is the space behind the driver unit 4.

[0217] The front opening of the sound duct 6 is configured to output the audio output from the driver unit 4 to the sound outlet 9 outside the housing 3.

[0218] The sound reproduction device 1B includes a sound-resistant component 51 that separates the front space 7a from the sound guiding space 8.

[0219] In other words, the front space 7a is the space surrounded by the box-shaped portion 5 of the housing 3, the driver unit 4, and the acoustic damping member 51, and is therefore an acoustically stable space. This makes it unlikely that the transfer function of the space from the driver unit 4 to the first microphone 11 will change.

[0220] In addition, the sound guiding space 8 is a space surrounded by the sound conduit 6 of the housing 3, the sound resistance component 51 and the sound outlet 9.

[0221] Note that dividing the space into two acoustic spaces is not limited to the case where the space is completely divided into two spaces by the acoustic damping member 51, and it is only necessary to obtain an effect similar to (or a similar effect to) the case where the space is acoustically completely divided into two spaces. For example, even as described later... Figure 17 and 18 As shown, a similar effect can be achieved by placing the acoustic damping member 51 in the portion between the two acoustic spaces, which can be regarded as an acoustically divided space.

[0222] The block diagram of the internal configuration of the sound reproduction device 1B has the same characteristics as... Figure 3 Similar configuration.

[0223] Through having Figure 3 and 7 The sound reproduction device 1B with the configuration shown can further prevent feedback while improving the noise cancellation performance of the first noise cancellation signal Snc1 generated based on the high-frequency component of the first sound collection signal S1, which is a signal collected in the front space 7a that becomes a stable space.

[0224] In addition, the second noise cancellation signal Snc2 is a signal that can bring the cancellation point closer to the tympanic membrane.

[0225] Therefore, by synthesizing a first noise cancellation signal Snc1 based on the high-frequency component of the first sound collection signal S1 and a second noise cancellation signal Snc2 based on the low-frequency component of the second sound collection signal S2 to generate a synthesized noise cancellation signal Snc, the noise cancellation performance at the tympanic membrane position can be further improved while preventing howling.

[0226] <3-2. Sound reproduction device as a headphone>

[0227] Figure 8 An example configuration of the audio reproduction device 1C as a headset is shown.

[0228] Note that, with Figure 2 The sound reproduction device 1 shown Figure 6 The sound reproduction device 1A shown is Figure 7 The components of the sound reproduction device 1B shown will be represented by the same reference numerals, and their descriptions will be omitted as appropriate.

[0229] The sound reproduction device 1C includes a housing 3 forming an internal space 2 therein, a driver unit 4 disposed in the internal space 2, and a first microphone 11 and a second microphone 12 for noise cancellation processing using a feedback scheme.

[0230] The driver unit 4 includes a diaphragm 4a to enable audio output.

[0231] The housing 3 includes a base portion 42 and an ear pad 43. The base portion 42 has an arrangement recess 41 to which the driver unit 4 is to be attached, and the ear pad 43 is to be attached to the front peripheral portion of the arrangement recess 41.

[0232] The inner front periphery of the ear pad 43 forms the sound outlet 9.

[0233] For example, a protective member 44, which is formed in a mesh shape, is attached to the front of the diaphragm 4a of the driver unit 4 to protect the diaphragm 4a.

[0234] The internal space 2 includes: a front space 7a, which is a space surrounded by the ear pad 43, the front surface of the driver unit 4 and the sound outlet 9; and a rear space 7b, which is a space surrounded by the base portion 42 and the rear surface of the driver unit 4.

[0235] The sound reproduction device 1C is provided with an acoustic damping member 51, which further divides the front space 7a into two acoustic spaces. Specifically, the front space 7a is divided by the acoustic damping member 51 into an inner space 52, which serves as the space on the side of the driver unit 4, and an outer space 53, which serves as the space on the side of the sound outlet 9. Note that the inner space 52 and the outer space 53 can also be regarded as the front space 7a and the sound guiding space 8 in the sound reproduction device 1 of the headphones.

[0236] Acoustic damping member 51 is attached to protective member 44, for example.

[0237] The first microphone 11 is attached to the rear surface of the protective member 44 such that the sound collecting surface 11a is substantially facing the diaphragm 4a.

[0238] The second microphone 12 is attached to the front surface of the acoustic damping member 51, such that the sound collecting surface 12a faces the sound emitting outlet 9.

[0239] In other words, the first microphone 11 and the second microphone 12 included in the sound reproduction device 1C are placed in different sound spaces separated by the acoustic damping member 51.

[0240] The block diagram of the internal configuration of the sound reproduction device 1C has a similar shape to... Figure 3 The configuration. In other words, in the sound reproduction device 1C, a first noise cancellation signal Snc1 is generated based on the high-frequency component of the first sound collection signal S1 from the first microphone 11.

[0241] Therefore, by using the first sound collection signal S1 of the first microphone 11 placed in the inner space 52, which serves as an acoustically stable space, to generate a synthetic noise cancellation signal Snc, it is possible to further prevent howling.

[0242] Furthermore, by using the low-frequency component of the second sound collection signal S2 to generate the synthesized noise cancellation signal Snc, the noise cancellation performance at the tympanic membrane position can be improved.

[0243] <4. Third Embodiment>

[0244] <4-1. As an audio reproduction device for headphones>

[0245] The sound reproduction device 1D, which serves as an earphone in the third embodiment, includes an acoustic damping member 51 that divides the internal space 2 into multiple sound spaces, and a second microphone 12 is positioned behind the driver unit 4.

[0246] This will refer to Figure 9 Detailed description.

[0247] The sound reproduction device 1D includes a housing 3 forming an internal space 2, a driver unit 4 disposed in the internal space 2, a first microphone 11, and a second microphone 12.

[0248] The interior space 2 includes the arrangement space 7 for each unit and the sound guiding space 8 surrounded by the sound conduit 6.

[0249] The arrangement space 7 includes a front space 7a, which serves as the space in front of the driver unit 4, and a rear space 7b, which serves as the space behind the driver unit 4.

[0250] The sound reproduction device 1D includes a sound-resistant component 51 that separates the front space 7a from the sound guiding space 8.

[0251] In other words, the front space 7a is a space surrounded by the box-shaped part 5 of the housing 3, the driver unit 4, and the acoustic damping member 51, and is therefore an acoustically stable space.

[0252] The first microphone 11 is positioned such that the sound-collecting surface 11a in the front space 7a is substantially facing the diaphragm 4a.

[0253] The second microphone 12 is positioned such that the sound collection surface 12a in the rear space 7b does not face the diaphragm 4a.

[0254] The block diagram of the internal configuration of the sound reproduction device 1D has a similar shape to... Figure 3 Configuration.

[0255] The second microphone 12, located in the rear space 7b, can collect sound pressure with a phase opposite to that emitted forward from the diaphragm 4a, as well as noise entering through the housing 3. Furthermore, the signal collected by the second microphone 12 can be made less susceptible to changes in the transfer function of the space from the driver unit to the microphone.

[0256] Therefore, by using the second sound collection signal S2 of the second microphone 12 to generate the synthetic noise cancellation signal Snc, the noise cancellation performance can be improved.

[0257] Note that in this example, an example has been described in which the first microphone 11 is placed in the front space 7a and the second microphone 12 is placed in the rear space 7b, but the first microphone 11 can be placed in the rear space 7b and the second microphone 12 can be placed in the sound guiding space 8.

[0258] <4-2. Sound reproduction device as a headphone>

[0259] Reference Figure 10 The third embodiment describes an audio reproduction device 1E as a headset.

[0260] Note that, compared with the various sound reproduction devices mentioned above (e.g., Figure 2 The sound reproduction device 1 shown Figure 6 Components of the sound reproduction device 1A shown in the figure will be represented by the same reference numerals and their descriptions will be omitted as appropriate.

[0261] The sound reproduction device 1E includes a housing 3 forming an internal space 2, a driver unit 4 disposed in the internal space 2, and a first microphone 11 and a second microphone 12 for noise cancellation processing using a feedback scheme.

[0262] The driver unit 4 includes a diaphragm 4a to enable audio output.

[0263] The housing 3 includes a base portion 42 and an ear pad 43. The front inner periphery of the ear pad 43 forms a sound outlet 9.

[0264] The protective member 44 is attached to the front of the diaphragm 4a of the driver unit 4.

[0265] The first microphone 11 is positioned in the front space 7a. Specifically, the first microphone 11 is attached to the rear surface of the protective member 44 such that the sound collecting surface 11a faces substantially the diaphragm 4a.

[0266] The second microphone 12 is housed in the rear space 7b. Specifically, the second microphone 12 is attached to the housing 3 such that the sound collecting surface 12a faces a different direction than the sound collecting surface 11a of the first microphone 11.

[0267] In other words, the first microphone 11 and the second microphone 12 included in the sound reproduction device 1E are placed in different sound spaces.

[0268] In the second microphone 12, which is placed in the rear space 7b, sound pressure with a phase opposite to that emitted forward from the diaphragm 4a, as well as noise entering through the housing 3, can be collected.

[0269] Therefore, by using the second sound collection signal S2 of the second microphone 12 to generate the synthetic noise cancellation signal Snc, the noise cancellation performance can be improved.

[0270] <5. Fourth Embodiment>

[0271] <5-1. Configuration of the Sound Reproduction Device>

[0272] Figure 11 An audio reproduction device 1F as an earphone is shown in the fourth embodiment. The audio reproduction device 1F according to the fourth embodiment includes a third microphone 61 for generating a feedforward noise cancellation signal.

[0273] Specifically, will refer to Figure 11 Describe the configuration of the sound reproduction device 1F.

[0274] The sound reproduction device 1F includes a housing 3 forming an internal space 2, a driver unit 4 disposed in the internal space 2, a first microphone 11 and a second microphone 12 for noise cancellation processing using a feedback scheme, and a third microphone 61 for noise cancellation processing using a feedforward scheme.

[0275] The interior space 2 includes the arrangement space 7 for each unit and the sound guiding space 8 surrounded by the sound conduit 6.

[0276] The arrangement space 7 includes a front space 7a, which is the space in front of the driver unit 4, and a rear space 7b, which is the space behind the driver unit 4.

[0277] The first microphone 11 is positioned such that the sound-collecting surface 11a in the front space 7a is substantially facing the diaphragm 4a.

[0278] The second microphone 12 is placed in the sound guiding space 8 such that the sound collecting surface 12a faces a different direction than the sound collecting surface 11a of the first microphone 11.

[0279] The third microphone 61 is attached to the housing 3 such that the sound collection surface 61a is located in the external space so as to be able to collect sound outside the sound reproduction device 1F.

[0280] As a result, feedback noise cancellation processing and feedforward noise cancellation processing can be combined to improve noise cancellation performance.

[0281] Note that the sound reproduction device 1F may include a sound-damping member 51 that separates the front space 7a from the sound guiding space 8.

[0282] As a result, the front space 7a is an acoustically stable space surrounded by the box-shaped portion 5 of the housing 3, the driver unit 4, and the acoustic damping member 51.

[0283] <5-2. Internal Configuration of the Sound Reproduction Device>

[0284] Figure 12 This is a block diagram of the internal configuration of the sound reproduction device 1F.

[0285] The sound reproduction device 1F includes a first amplifier 21A, a first ADC 22A, and a first DSP 23A, as units for performing processing on the first sound collection signal S1 from the first microphone 11.

[0286] In addition, the sound reproduction device 1F includes a second amplifier 21B, a second ADC 22B, and a second DSP 23B as units for performing processing on the sound collection signal S2 from the second microphone 12.

[0287] In addition, the sound reproduction device 1 includes a third amplifier 21C, a third ADC 22C and a third DSP 23C as units for performing processing on the sound collection signal S3 of the third microphone 61.

[0288] The audio reproduction device 1F includes adders 24 and 25, an equalizer circuit 26, a DAC 27, and a power amplifier 28, and also includes adder 62.

[0289] As described above, the first sound collection signal S1 is obtained by collecting the sound of noise contained in the space 7a in front of the diaphragm 4a of the driver unit 4.

[0290] The first sound collection signal S1 is amplified by the first amplifier 21A, converted into a digital signal by the first ADC 22A, and input to the first DSP 23A.

[0291] The first DSP 23A includes a digital filter for generating a feedback noise cancellation signal (see [link]). Figure 4 ).

[0292] The signal generated by the first DSP 23A is input to the adder 24.

[0293] As described above, the second sound collection signal S2 is obtained by collecting sound containing noise from the sound guiding space 8, which is the internal space of the sound conduit 6.

[0294] The second sound collection signal S2 is amplified by the second amplifier 21B, converted into a digital signal by the second ADC 22B, and input to the second DSP 23B.

[0295] The second DSP 23B includes a digital filter for generating a feedback noise cancellation signal (see [link]). Figure 5 ).

[0296] The signal generated by the second DSP 23B is input to the adder 24.

[0297] Adder 24 adds and synthesizes the first noise cancellation signal Snc1 generated based on the first sound collection signal S1 of the first microphone 11 and the second noise cancellation signal Snc2 generated based on the second sound collection signal S2 of the second microphone 12, and outputs the result to adder 62.

[0298] A third sound collection signal S3 is obtained by collecting the sound contained in the external space of the sound reproduction device 1F.

[0299] The third sound collection signal S3 is amplified by the third amplifier 21C, converted into a digital signal by the third ADC 22C, and input to the third DSP 23C.

[0300] The third DSP 23C includes a digital filter for generating a feedforward noise cancellation signal. Specifically, such as... Figure 13 As shown, the third FF filter 63 is set.

[0301] The third FF filter 63 is a digital filter used to generate a feedforward digital noise cancellation signal. In other words, the third FF filter 63 generates a third noise cancellation signal Snc3 based on the third sound collection signal S3.

[0302] The third noise cancellation signal Snc3 generated in the third DSP 23C is input to adder 62.

[0303] Adder 62 adds the first noise cancellation signal Snc1 generated based on the first sound collection signal S1 of the first microphone 11, the second noise cancellation signal Snc2 generated based on the second sound collection signal S2 of the second microphone 12, and the third noise cancellation signal Snc3 generated based on the third sound collection signal S3 of the third microphone 61 and synthesizes the synthesized signal, and outputs the result as the synthesized noise cancellation signal Snc to adder 25.

[0304] In addition to the synthesized noise cancellation signal Snc, a digital signal based on the sound source signal Sm is also input to the adder 25.

[0305] The sound source signal Sm is input to the equalizer circuit 26.

[0306] The equalizer circuit 26 performs equalization processing on the input sound source signal Sm for sound quality correction and sound quality effect processing, and outputs the obtained digital signal to the adder 25.

[0307] The equalizer circuit 26 can be configured, for example, within a DSP.

[0308] Adder 25 adds and synthesizes the synthesized noise cancellation signal Snc and the signal from equalizer circuit 26, and outputs the result as an output audio signal to DAC 27.

[0309] The output signal from adder 25 is converted into an analog signal by DAC 27, then amplified by power amplifier 28 and provided to driver unit 4.

[0310] In driver unit 4, audio output processing based on input and output audio signals is performed. As a result, the listener hears a reproduced sound with reduced noise at a predetermined noise cancellation point.

[0311] like Figure 11 As shown, the first microphone 11 is positioned such that the sound collecting surface 11a faces the diaphragm 4a of the driver unit 4, so that the first noise cancellation signal Snc1 can prevent howling from occurring.

[0312] Furthermore, by using the second sound collection signal S2 of the second microphone 12 (where the sound collection surface 12a faces a direction different from that of the first microphone 11), the cancellation point can be made closer to the tympanic membrane.

[0313] Furthermore, the sound collection surface 61a is configured to pick up noise in the external space of the sound reproduction device 1F, so that noise cancellation processing can be performed using a feedforward scheme.

[0314] Noise cancellation performance can be improved by using the third sound collection signal S3 of the third microphone 61.

[0315] Although Figure 12 An example is shown in which a first DSP 23A, a second DSP 23B, and a third DSP 23C are configured, but a digital filter for the first sound collection signal S1, a digital filter for the second sound collection signal S2, and a digital filter for the third sound collection signal S3 can be formed in a single DSP.

[0316] Furthermore, in this case, the equalizer circuit 26 can be formed in the same DSP.

[0317] Note that, although Figure 3 An example is shown where the sound source signal Sm is a digital signal, but the sound source signal Sm can also be an analog signal. In this case, an ADC is used to convert the sound source signal Sm into a digital signal and input it to the equalizer circuit 26.

[0318] Furthermore, the sound reproduction device 1F in the fourth embodiment can be a sound reproduction device as headphones, including a third microphone 61, in which case a similar effect can be obtained.

[0319] <6. Revision>

[0320] <6-1. First Revision>

[0321] In each of the above examples, an example has been described in which a digital filter is set for each of the first sound collection signal S1 and the second sound collection signal S2 to generate a noise cancellation signal.

[0322] In other words, as referenced Figure 3 , 4 As described in 5, in the sound reproduction device 1, a first FB filter 32 is provided as a digital filter for generating a first noise cancellation signal Snc1 using a first sound collection signal S1, and a second FB filter 34 is provided as a digital filter for generating a second noise cancellation signal Snc2 using a second sound collection signal S2.

[0323] To reduce the computational load of digital filter processing, only one digital filter can be set up to generate the synthetic noise cancellation signal Snc.

[0324] Specifically, will refer to Figure 14 The description describes the internal configuration of an audio reproduction device 1G with only one digital filter for generating the synthetic noise cancellation signal Snc.

[0325] The sound reproduction device 1G includes a first amplifier 21A, a first ADC 22A, and an HPF71 as units for processing the first sound collection signal S1 from the first microphone 11. In other words, the sound reproduction device 1G does not include a first DSP that performs digital filtering processing on the first sound collection signal S1.

[0326] The first sound collection signal S1 is amplified by the first amplifier 21A, then converted into a digital signal by the first ADC 22A, and further, the low-frequency component is removed by the HPF 71 and input to the adder 73.

[0327] The sound reproduction device 1G includes a second amplifier 21B, a second ADC 22B, and an LPF 72 as units for processing the second sound collection signal S2 from the second microphone 12. In other words, the sound reproduction device 1G does not include a second DSP for performing digital filtering processing on the second sound collection signal S2.

[0328] The second sound collection signal S2 is amplified by the second amplifier 21B, then converted into a digital signal by the second ADC 22B, and further, the high-frequency components are removed by the LPF 72 and input to the adder 73.

[0329] Adder 73 adds and synthesizes the high-frequency component of the first sound collection signal S1 from the first microphone 11 and the low-frequency component of the second sound collection signal S2 from the second microphone 12, and outputs the result to FB filter 74, which is a digital filter used to generate noise cancellation signal.

[0330] The FB filter 74 performs digital filtering processing on the summed and synthesized sound collection signal to generate the noise cancellation signal Snc'.

[0331] The generated noise cancellation signal Snc' can be regarded as the above-mentioned synthetic noise cancellation signal Snc.

[0332] Adder 25 adds and synthesizes the noise cancellation signal Snc' and the signal from equalizer circuit 26, and outputs the result as the output audio signal to DAC 27.

[0333] DAC 27 converts the input signal from adder 25 into an analog signal and outputs the analog signal to power amplifier 28.

[0334] Power amplifier 28 amplifies the input signal and provides the amplified signal to driver unit 4.

[0335] In driver unit 4, audio output processing based on the input audio signal is performed.

[0336] Note that it is possible to set it in the pre-stage instead of the post-stage of the first ADC 22. Figure 14 The HPF 71 shown here. In other words, it can perform filtering on analog signals.

[0337] Similarly, LPF 72 can be set in the preamp of the second ADC 22B.

[0338] Note that the HPF 71 can be replaced with a high-shelf filter, a high-peak EQ filter, etc. Similarly, the LPF 72 can be replaced with a low-shelf filter, a low-peak EQ filter, etc.

[0339] Alternatively, a configuration can be used in which only the FB filter 74 is set instead of HPF 71 and LPF 72.

[0340] <6-2. Second Revision>

[0341] In the second embodiment, an example of providing an acoustic damping member 51 in the sound reproduction devices 1B and 1C is described.

[0342] Here, the attachment mode of the acoustic impedance member 51 will be described by way of example using a headphone-type audio reproduction device 1C.

[0343] Figure 15A first example of attaching acoustic damping member 51 to protective member 44 is shown. Acoustic damping member 51 (shown by shading) can be attached to the entire front surface of protective member 44.

[0344] As a result, the space in front of the acoustic damping member 51 (e.g., the outer space 53) and the space behind the acoustic damping member 51 (e.g., the inner space 52) can be acoustically separated. This makes the rear space more acoustically stable and can prevent howling.

[0345] Figure 16 A second example of attaching acoustic damping member 51 to protective member 44 is shown. Acoustic damping member 51 (shown by shading) can be attached from the front to cover approximately the central portion of protective member 44.

[0346] In this case, it is preferable to position the first microphone 11 at the center of the acoustic impedance member 51.

[0347] Figure 17 A third example of attaching acoustic damping member 51 to protective member 44 is shown. Acoustic damping member 51 (shown by shading) can be attached from the front to cover the upper, lower, right, and left halves of protective member 44.

[0348] Furthermore, in this case, preferably, the acoustic damping member 51 is positioned offset relative to the central portion of the protective member 44 to the portion covered by the acoustic damping member 51.

[0349] Figure 18 A fourth example of attaching acoustic damping member 51 to protective member 44 is shown. Acoustic damping member 51 (shown by shading) can be attached from the front to cover the central portion of protective member 44 from top to bottom.

[0350] Furthermore, in this case, the first microphone 11 is preferably positioned at the center of the acoustic impedance member 51.

[0351] In addition to Figure 15 The acoustic damping member 51 shown is attached to the entire surface of the protective member 44 in a configuration that, even with, Figure 16 , 17 With the configuration shown in Figure 18, the rear space can also become an acoustically stable space, thereby preventing feedback.

[0352] <6-3. Other>

[0353] Note that in each of the examples above, headphones and earphones are considered as examples of sound reproduction devices, but other examples are conceivable. For example, the above configuration can also be applied to noise cancellation signals generated for performing noise cancellation processing in a space of a specific size (e.g., a room).

[0354] In other words, the first and second control rooms (MCs) used for FB control are located within the room. In this case, the second MC is positioned closer to the window or door than the first MC.

[0355] In addition, a third MC for FF control can be set up outside the room.

[0356] In this way, when the listener is listening to music in a room that serves as an audio space, a space with reduced noise can be provided, which is suitable for listening.

[0357] <7. Conclusion>

[0358] The audio reproduction device 1 (1A, 1B, 1C, 1D, 1E and 1G) such as headphones or earphones as described above includes: a first microphone 11 for noise cancellation processing using a feedback scheme; a second microphone 12 including a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone 11, and for noise cancellation processing using a feedback scheme; and an audio signal processing unit (first DSP 23A, second DSP 23B, etc.) configured to generate a noise cancellation signal using a first sound collection signal S1 collected by the first microphone 11 and a second sound collection signal S2 collected by the second microphone 12.

[0359] In a configuration that includes multiple microphones for noise cancellation processing using a feedback scheme, sound can be easily collected in multiple acoustic spaces (e.g., the front space 7a of the driver unit 4 and the space in the sound duct (sound guiding space 8)) in the sound reproduction device 1.

[0360] Using multiple microphones for a feedback scheme can help improve noise cancellation. Furthermore, by changing the sound collection direction of each microphone, acoustic signals containing noise can be appropriately collected in multiple spaces, which is suitable for using a feedback scheme to improve noise cancellation.

[0361] As in the first embodiment ( Figure 2 As described in the document, in the audio reproduction device 1, the sound collecting surface 11a of the first microphone 11 can be located closer to the driver unit 4 than the sound collecting surface 12a of the second microphone 12, and the driver unit 4 is configured to perform audio output based on the noise cancellation signal.

[0362] This makes it unlikely that the transfer function of the space from the driver unit 4 to the sound collection surface 11a of the first microphone 11 will change.

[0363] Therefore, the filter coefficients set in the first FB filter 32 can be used to generate a first noise cancellation signal Snc1 with sufficient noise cancellation performance. In other words, the noise cancellation performance can be improved by adding the first noise cancellation signal Snc1 generated by the sound collection signal from the first microphone 11.

[0364] As in the first embodiment ( Figure 2 As described above, in the sound reproduction device 1, the sound collection surface 11a of the first microphone 11 can be positioned toward the sound emission direction (front) of the driver unit 4, which is configured to perform sound output based on a noise cancellation signal.

[0365] This makes it unlikely that the transfer function of the space from the driver unit 4 to the sound collection surface 11a of the first microphone 11 will change.

[0366] Therefore, the filter coefficients set in the first FB filter 32 can be used to generate a first noise cancellation signal Snc1 with sufficient noise cancellation performance. In other words, the noise cancellation performance can be improved by adding the first noise cancellation signal Snc1 generated by the sound collection signal from the first microphone 11.

[0367] As in the first embodiment ( Figure 2 As described in the document, the sound reproduction device 1 may further include a housing 3 in which a driver unit 4 is disposed, the driver unit 4 being configured to output sound based on a noise cancellation signal and having a sound output outlet 9 through which output sound from the driver unit 4 is emitted, and a first microphone 11 and a second microphone 12 may be disposed in the housing 3, and the second microphone 12 may be closer to the sound output outlet 9 than the first microphone 11.

[0368] As a result, the second microphone 12 can collect sound at a location closer to the eardrum than the first microphone 11.

[0369] This allows the cancellation point to be closer to the eardrum, thereby improving noise cancellation performance.

[0370] As in the first embodiment ( Figure 2 and Figure 6 ), Second embodiment ( Figure 7 and Figure 8 ), Third embodiment ( Figure 9 and Figure 10 ) and the fourth embodiment ( Figure 11As described in the above, in the sound reproduction device 1, the sound collection surface 12a of the second microphone 12 can be positioned not towards the sound emission direction (front) of the driver unit 4 configured to perform sound output based on the noise cancellation signal.

[0371] This makes it easier for the second microphone 12 to collect noise.

[0372] Therefore, noise cancellation performance can be improved.

[0373] As in the first embodiment ( Figure 6 As described in the document, in the sound reproduction device 1, at least one sound space can be positioned in the housing 3 along the sound emission direction of the driver unit 4, and the first microphone 11 and the second microphone 12 can be positioned in one sound space.

[0374] As a result, noise components in the acoustic space where the microphone is placed can be collected with high precision.

[0375] This allows for more appropriate settings of the filter coefficients, thereby improving noise cancellation performance.

[0376] Furthermore, there is no need for components to divide the sound space into multiple spaces. This reduces manufacturing-related costs. Additionally, the reduced number of parts allows for a reduction in the number of assembly steps.

[0377] As in the first embodiment ( Figure 6 ), Second embodiment ( Figure 8 ) and the third embodiment ( Figure 10 As described in the above, in the sound reproduction device 1, the first microphone 11 can be positioned such that the sound collecting surface 11a faces the sound emission direction of the driver unit 4, and the second microphone 12 can be positioned such that the sound collecting surface 12a faces the same direction as the sound emission direction of the driver unit 4.

[0378] As a result, the transfer function of the space from the driver unit 4 to the sound collection surface 11a of the first microphone 11 is unlikely to change. Furthermore, the second microphone 12 readily collects noise near the tympanic membrane.

[0379] Therefore, by using both the first sound collection signal S1 from the first microphone 11 and the second sound collection signal S2 from the second microphone 12 to generate a noise cancellation signal, noise cancellation performance can be improved while preventing howling.

[0380] As in the first embodiment ( Figure 2 ), Second embodiment ( Figure 7 and 8 ), Third embodiment ( Figure 9 , Figure 10As described above, in the sound reproduction device 1, the first microphone 11 and the second microphone 12 can be placed in different sound spaces.

[0381] This makes the noise collected by the first microphone 11 different from the noise collected by the second microphone 12.

[0382] Therefore, noise cancellation performance can be improved by generating a noise cancellation signal based on both the first sound collection signal S1 from the first microphone 11 and the second sound collection signal S2 from the second microphone 12.

[0383] As in the first embodiment ( Figure 2 ), Second embodiment ( Figure 7 and 8 ), Third embodiment ( Figure 9 , Figure 10 As described above, in the sound reproduction device 1, multiple sound spaces can be provided in the housing 3, and the first microphone 11 and the second microphone 12 can be located in different spaces of the multiple sound spaces.

[0384] In this way, both the first microphone 11 and the second microphone 12 are housed within the housing 3. Furthermore, the noise collected by the first microphone 11 and the noise collected by the second microphone 12 become more distinct from each other.

[0385] Therefore, sound collection signals can be obtained at different locations within the housing, thereby improving noise cancellation performance.

[0386] As in the second embodiment ( Figure 7 and Figure 8 As described above, in the sound reproduction device 1, a sound-blocking member 51 can be installed to separate the first sound space (front space 7a, inner space 52) where the first microphone 11 is located from the second sound space (sound guiding space 8) where the second microphone 12 is located.

[0387] For an acoustic space (front space 7a), this can achieve a stable space in which the transfer function of the space from driver unit 4 to microphone (first microphone 11) is unlikely to change.

[0388] Therefore, high noise cancellation can be achieved using the set filter coefficients.

[0389] As in the second embodiment ( Figure 7 and Figure 8As described in [references to other documents], the sound reproduction device 1 may further include a housing 3 in which a driver unit 4 configured to perform sound output based on a noise cancellation signal is disposed, and has a sound output outlet 9 through which output sound from the driver unit 4 is emitted. The first sound space (front space 7a) may be the space surrounded by the driver unit 4, the acoustic damping member 51 and the housing 3, and the second sound space (sound guiding space 8) may be the space surrounded by the acoustic damping member 51, the housing 3 and the sound output outlet 9.

[0390] As a result, the first acoustic space becomes a stable space, in which the transfer function is unlikely to change. Furthermore, the second acoustic space becomes a space where noise from near the eardrum is easily collected.

[0391] By using a first sound space that is positioned as an acoustically stable space ( Figure 2 The space in front 7a, Figure 8 The first sound collection signal S1 of the first microphone 11 in the inner space 52 (etc.) generates a first noise cancellation signal Snc1, which can make the filter coefficients set for the first FB filter 32 suitable for having high noise cancellation performance.

[0392] Furthermore, there are cases where sound reproduction devices such as headphones and headsets can become deformed depending on the usage conditions. In such cases, the spatial transfer function changes, making the filter coefficients unsuitable, which may lead to feedback, etc. Even in this case, by using the acoustic damping member 51 to shield the first acoustic space from the outside to maintain an acoustically stable state, the proper setting of the filter coefficients can be ensured, which can prevent feedback from occurring.

[0393] However, there exists a situation where the microphone (first microphone 11) positioned in a stable space cannot adequately collect noise near the point where the desired noise cancellation effect is desired (i.e., near the tympanic membrane). When noise cannot be adequately collected, the generated noise cancellation signal is unsuitable, and the active noise cancellation effect is reduced at the tympanic membrane location.

[0394] According to this configuration, a second sound space, located in a different location than the first sound space, is used. Figure 2 Sound-guided space 8 Figure 8 The second sound collection signal S2 of the second microphone 12 in the outer space 53 (etc.) generates a second noise cancellation signal Snc2, so that it can exhibit high noise cancellation performance while preventing howling.

[0395] As in the third embodiment ( Figure 9 and Figure 10As described above, in the sound reproduction device 1, the first microphone 11 may be located in front of the sound emission direction of the driver unit 4, which performs sound output based on the noise cancellation signal, and the second microphone 12 may be located behind the driver unit 4.

[0396] As a result, for example, the second microphone 12 located behind the driver unit 4 can collect sound with a phase opposite to that of the audio output. Furthermore, in the second microphone 12, the transfer function of the space from the driver unit 4 to the sound collection surface 12a of the second microphone 12 is unlikely to change with the listener's wearing state.

[0397] In this case, the second microphone 12 also collects noise that was not completely removed by the noise cancellation signal generated based on the first sound collection signal S1 from the first microphone 11.

[0398] Therefore, by generating a noise cancellation signal based not only on the first sound collection signal S1 of the first microphone 11 but also on the second sound collection signal S2 of the second microphone 12, high noise cancellation performance can be achieved.

[0399] As in the first embodiment ( Figure 4 and Figure 5 The audio reproduction device 1 may further include: a first feedback filter (first FB filter 32) configured to generate a first noise cancellation signal Snc1 based on the high-frequency component of the first sound collection signal S1; and a second feedback filter (second FB filter 34) configured to generate a second noise cancellation signal Snc2 based on the low-frequency component of the second sound collection signal S2, and the audio signal processing unit may generate a noise cancellation signal based on the first noise cancellation signal Snc1 and the second noise cancellation signal Snc2.

[0400] The first microphone 11 is positioned closer to the driver unit 4 than the second microphone 12, so the filter coefficients set for the first FB filter 32 are unlikely to be less suitable than the filter coefficients set for the second FB filter 34. This makes the first noise cancellation signal Snc1 based on the first sound collection signal S1 less likely to cause feedback than the second noise cancellation signal Snc2 based on the second sound collection signal S2.

[0401] Therefore, for the high-frequency components where feedback is likely to occur, a first noise cancellation signal Snc1, which is less likely to cause feedback, is generated using the first sound collection signal S1; and for the low-frequency components where feedback is less likely to occur, a second noise cancellation signal Snc2, which has improved noise cancellation performance, is generated using the second sound collection signal S2. By using these signals to generate the noise cancellation signals, noise cancellation performance can be improved while preventing feedback.

[0402] As in the first embodiment ( Figure 4 and Figure 5 As described above, in the sound reproduction device 1, the high-frequency component of the first sound collection signal S1 can be extracted by a high-pass filter HPF 31, a high-shelf filter or a high-peak EQ filter, and the low-frequency component of the second sound collection signal S2 can be extracted by a low-pass filter LPF 33, a low-shelf filter or a low-peak EQ filter.

[0403] As a result, the high-frequency component of the sound signal, which is more likely to cause feedback, can be input into the feedback loop of the first microphone 11, where the transfer function of the space from the driver unit 4 to the microphone is unlikely to change. Furthermore, the low-frequency component of the sound signal can be input into the feedback loop of the second microphone 12, which is more likely to collect noise closer to the eardrum.

[0404] Therefore, feedback can be prevented. Furthermore, the noise cancellation performance based on the second sound collection signal S2 can be improved by removing the low-frequency component of the first sound collection signal S1.

[0405] As in the fourth embodiment ( Figure 11 As described above, the audio reproduction device 1 may also include a third microphone 61 for noise cancellation processing using a feedforward scheme, and the audio signal processing unit (first DSP 23A, second DSP 23B, third FF filter 63, etc.) may generate a noise cancellation signal by using a first sound collection signal S1, a second sound collection signal S2 and a third sound collection signal S3 collected by the third microphone 61.

[0406] For example, it is conceivable to set up a third microphone 61 to collect external sounds from the sound reproduction device 1F.

[0407] Noise cancellation performance can be improved by using the third sound collection signal S3 of the third microphone 61 described herein.

[0408] As shown in the various embodiments described above, the signal processing apparatus includes an audio signal processing unit (first DSP 23A, second DSP 23B, etc.), which is configured to generate a noise cancellation signal using a first sound collection signal S1 collected by a first microphone 11 for noise cancellation processing using a feedback scheme and a second sound collection signal S2 collected by a second microphone 12, the second microphone 12 including a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone 11, and for noise cancellation processing using a feedback scheme.

[0409] Furthermore, the signal processing method executed by the signal processing device is a method that includes generating a noise cancellation signal using a first sound collection signal S1 collected by a first microphone 11 for noise cancellation processing using a feedback scheme and a second sound collection signal S2 collected by a second microphone 12, the second microphone 12 including a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone 11, and for noise cancellation processing using a feedback scheme.

[0410] Based on such a signal processing device and method, it is easy to set up a state for sound collection in multiple acoustic spaces (e.g., the space 7a in front of the driver unit 4 and the space in the sound duct (sound guiding space 8)) within the sound reproduction device 1. Therefore, by using multiple microphones for the feedback scheme, the noise cancellation effect can be improved. Furthermore, by changing the sound collection direction of each microphone, sound signals containing noise from multiple spaces can be appropriately collected. This can improve the noise cancellation effect through the feedback scheme.

[0411] Furthermore, the beneficial effects described in this specification are merely illustrative and not limiting, and other beneficial effects may be achieved.

[0412] Furthermore, the above examples can be combined in any way, as long as combination is possible.

[0413] <8. This technology>

[0414] Note that the headset device based on this technology can also adopt the following configuration.

[0415] (1) An audio reproduction device, comprising:

[0416] The first microphone is used for noise cancellation processing using a feedback scheme;

[0417] A second microphone, including a sound-collecting surface in a direction different from that of the first microphone, and used for noise cancellation processing using a feedback scheme; and

[0418] The audio signal processing unit is configured to generate a noise cancellation signal using a first sound collection signal collected by a first microphone and a second sound collection signal collected by a second microphone.

[0419] (2) The sound reproduction device according to (1),

[0420] In this configuration, the sound collection surface of the first microphone is located closer to the driver unit configured to perform audio output based on the noise cancellation signal, compared to the sound collection surface of the second microphone.

[0421] (3) The sound reproduction device according to any one of (1) to (2),

[0422] The sound-collecting surface of the first microphone is located in the direction of sound emission of the driver unit configured to perform audio output based on a noise cancellation signal.

[0423] (4) The sound reproduction device according to any one of (1) to (3) further includes:

[0424] The housing contains a driver unit configured to perform audio output based on a noise cancellation signal, and has a sound output outlet through which the output sound from the driver unit is emitted.

[0425] The first microphone and the second microphone are housed within the housing, and

[0426] The second microphone is located closer to the sound output outlet than the first microphone.

[0427] (5) The sound reproduction device according to any one of (1) to (4),

[0428] The sound-collecting surface of the second microphone is located at a position not facing the sound emission direction of the driver unit configured to perform audio output based on the noise cancellation signal.

[0429] (6) The sound reproduction device according to (4),

[0430] Wherein, at least one acoustic space within the housing is located in the direction of sound emission from the driver unit, and

[0431] The first and second microphones are located in an acoustic space.

[0432] (7) The sound reproduction device according to (6),

[0433] The first microphone is positioned such that its sound-collecting surface faces the direction of sound emission from the driver unit, and

[0434] The second microphone is positioned such that the sound collection surface faces the same direction as the sound emission direction of the driver unit.

[0435] (8) The sound reproduction apparatus according to any one of (1) to (5),

[0436] The first and second microphones are placed in different audio spaces.

[0437] (9) The sound reproduction device according to (4) or (6),

[0438] Multiple acoustic spaces are provided within the housing, and

[0439] The first microphone and the second microphone are located in different spaces within the plurality of acoustic spaces.

[0440] (10) The sound reproduction device according to (8),

[0441] It includes an acoustic damping component that separates the first acoustic space where the first microphone is located from the second acoustic space where the second microphone is located.

[0442] (11) The sound reproduction device according to (10) further includes:

[0443] The housing contains a driver unit configured to perform audio output based on a noise cancellation signal, and has a sound output outlet through which the output sound from the driver unit is emitted.

[0444] The first acoustic space is a space surrounded by the driver unit, the acoustic damping member, and the housing.

[0445] The second acoustic space is a space surrounded by acoustic damping components, a shell, and a sound outlet.

[0446] (12) The sound reproduction apparatus according to any one of (1) to (11),

[0447] The first microphone is located in front of the sound emission direction of the driver unit that performs audio output based on the noise cancellation signal, and

[0448] The second microphone is located on the rear side of the driver unit.

[0449] (13) The sound reproduction device according to (2) further includes:

[0450] A first feedback filter is configured to generate a first noise cancellation signal based on the high-frequency components of the first sound collection signal; and

[0451] The second feedback filter is configured to generate a second noise cancellation signal based on the low-frequency component of the second sound collection signal.

[0452] The audio signal processing unit generates the noise cancellation signal based on the first noise cancellation signal and the second noise cancellation signal.

[0453] (14) The sound reproduction device according to (13),

[0454] Among them, the high-frequency components of the first sound collection signal are extracted using a high-pass filter, a high-shelf filter, or a high-peak EQ filter, and

[0455] The low-frequency components of the second sound collection signal are extracted using a low-pass filter, a low-shelf filter, or a low-peak EQ filter.

[0456] (15) The sound reproduction device according to any one of (1) to (14) further comprises:

[0457] The third microphone is used for noise cancellation processing using a feedforward scheme.

[0458] The audio signal processing unit generates a noise cancellation signal by using a first sound collection signal, a second sound collection signal, and a third sound collection signal collected by a third microphone.

[0459] (16) A signal processing apparatus, comprising:

[0460] An audio signal processing unit is configured to generate a noise cancellation signal using a first sound collection signal collected by a first microphone for noise cancellation processing using a feedback scheme and a second sound collection signal collected by a second microphone, the second microphone including a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone, and for noise cancellation processing using a feedback scheme.

[0461] (17) A signal processing method, comprising:

[0462] A noise cancellation signal is generated using a first sound collection signal collected by a first microphone for noise cancellation processing using a feedback scheme and a second sound collection signal collected by a second microphone, the second microphone including a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone, and used for noise cancellation processing using a feedback scheme.

[0463] Reference Mark List

[0464] 1, 1A, 1B, 1C, 1D, 1E, 1F Sound reproduction devices

[0465] 3 shells

[0466] 4 driver units

[0467] 7a Front space (first sound space)

[0468] 8. Sound Guiding Space (Second Sound Space)

[0469] 9 sound outputs

[0470] 11 First Microphone

[0471] 11a Sound Collection Surface

[0472] 12 Second Microphone

[0473] 12a Sound Collection Surface

[0474] 23A First DSP (Audio Signal Processing Unit)

[0475] 23B Second DSP (Audio Signal Processing Unit)

[0476] 31HPF

[0477] 32 First FB Filter

[0478] 33LPF

[0479] 34 Second FB Filter

[0480] 51 Acoustic Damper Components

[0481] 52. Inner space (first acoustic space)

[0482] 61 Third Microphone

[0483] 63 Third FF Filter 71HPF

[0484] 72LPF S1 First sound collection signal S2 Second sound collection signal S3 Third sound collection signal Snc1 First noise cancellation signal Snc2 Second noise cancellation signal Snc Synthetic noise cancellation signal

Claims

1. An audio reproduction device, comprising: The first microphone is used for noise cancellation processing using a feedback scheme; The second microphone includes a sound collection surface in a direction different from that of the first microphone, and is used for noise cancellation processing using a feedback scheme; The audio signal processing unit is configured to generate a noise cancellation signal using a first sound collection signal collected by a first microphone and a second sound collection signal collected by a second microphone. A first feedback filter is configured to generate a first noise cancellation signal based on the high-frequency components of the first sound collection signal; The second feedback filter is configured to generate a second noise cancellation signal based on the low-frequency component of the second sound collection signal; The housing contains a driver unit configured to perform audio output based on a noise cancellation signal, and has a sound output outlet through which the output sound from the driver unit is emitted. The audio signal processing unit generates the noise cancellation signal based on the first noise cancellation signal and the second noise cancellation signal. The sound-collecting surface of the first microphone is located closer to the driver unit, which is configured to perform audio output based on noise cancellation signals, compared to the sound-collecting surface of the second microphone. The first and second microphones were placed in different audio spaces. It includes an acoustic damping component that separates the first acoustic space where the first microphone is located from the second acoustic space where the second microphone is located. The first acoustic space is a space surrounded by the driver unit, the acoustic damping member, and the housing. The second acoustic space is a space surrounded by acoustic damping components, a shell, and a sound output outlet. The first microphone is located in front of the sound emission direction of the driver unit that performs audio output based on the noise cancellation signal, and The second microphone is located on the rear side of the driver unit.

2. The sound reproduction device according to claim 1, in, The sound-collecting surface of the first microphone is located in the direction of sound emission of the driver unit configured to perform audio output based on noise cancellation signals.

3. The sound reproduction device according to claim 1, further comprising: The housing contains a driver unit configured to perform audio output based on a noise cancellation signal, and has a sound output outlet through which the output sound from the driver unit is emitted. The first microphone and the second microphone are housed within the housing, and The second microphone is located closer to the sound output outlet than the first microphone.

4. The sound reproduction device according to claim 1, in, The sound-collecting surface of the second microphone is located in a position not facing the sound emission direction of the driver unit configured to perform audio output based on the noise cancellation signal.

5. The sound reproduction device according to claim 3, in, At least one acoustic space within the housing is located in the direction of sound emission from the driver unit, and The first and second microphones are located in an acoustic space.

6. The sound reproduction device according to claim 5, in, The first microphone is positioned such that the sound collection surface faces the direction of sound emission from the driver unit, and The second microphone is positioned such that the sound collection surface faces the same direction as the sound emission direction of the driver unit.

7. The sound reproduction device according to claim 3, in, Multiple acoustic spaces are provided within the housing, and The first microphone and the second microphone are located in different spaces within the plurality of acoustic spaces.

8. The sound reproduction device according to claim 1, in, The high-frequency components of the first sound collection signal are extracted using a high-pass filter, a high-shelf filter, or a high-peak EQ filter. The low-frequency components of the second sound collection signal are extracted using a low-pass filter, a low-shelf filter, or a low-peak EQ filter.

9. The sound reproduction device according to claim 1, further comprising: The third microphone is used for noise cancellation processing using a feedforward scheme. The audio signal processing unit generates a noise cancellation signal by using a first sound collection signal, a second sound collection signal, and a third sound collection signal collected by a third microphone.

10. A signal processing apparatus, comprising: An audio signal processing unit is configured to generate a noise cancellation signal using a first sound collection signal collected by a first microphone for noise cancellation processing using a feedback scheme and a second sound collection signal collected by a second microphone, the second microphone including a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone, and for noise cancellation processing using a feedback scheme; A first feedback filter is configured to generate a first noise cancellation signal based on the high-frequency components of the first sound collection signal; as well as The second feedback filter is configured to generate a second noise cancellation signal based on the low-frequency component of the second sound collection signal. The audio signal processing unit generates the noise cancellation signal based on the first noise cancellation signal and the second noise cancellation signal. The sound-collecting surface of the first microphone is located closer to the driver unit, which is configured to perform audio output based on noise cancellation signals, compared to the sound-collecting surface of the second microphone. The first and second microphones were placed in different audio spaces. It includes an acoustic damping component that separates the first acoustic space where the first microphone is located from the second acoustic space where the second microphone is located. The first acoustic space is a space surrounded by the driver unit, the acoustic damping member, and a housing. The housing houses the driver unit configured to perform acoustic output based on a noise cancellation signal and has a sound output outlet through which the output sound from the driver unit is emitted. The second acoustic space is a space surrounded by acoustic damping components, a shell, and a sound output outlet. The first microphone is located in front of the sound emission direction of the driver unit that performs audio output based on the noise cancellation signal, and The second microphone is located on the rear side of the driver unit.

11. A signal processing method, comprising: A noise cancellation signal is generated using a first sound collection signal collected by a first microphone for noise cancellation processing using a feedback scheme and a second sound collection signal collected by a second microphone, wherein the second microphone includes a sound collection surface in a direction different from the direction of the sound collection surface of the first microphone, and is used for noise cancellation processing using a feedback scheme. A first noise cancellation signal is generated based on the high-frequency components of the first sound collection signal; as well as A second noise cancellation signal is generated based on the low-frequency component of the second sound collection signal. The noise cancellation signal is generated based on the first noise cancellation signal and the second noise cancellation signal. The sound-collecting surface of the first microphone is located closer to the driver unit, which is configured to perform audio output based on noise cancellation signals, compared to the sound-collecting surface of the second microphone. The first and second microphones were placed in different audio spaces. It includes an acoustic damping component that separates the first acoustic space where the first microphone is located from the second acoustic space where the second microphone is located. The first acoustic space is a space surrounded by the driver unit, the acoustic damping member, and a housing. The housing houses the driver unit configured to perform acoustic output based on a noise cancellation signal and has a sound output outlet through which the output sound from the driver unit is emitted. The second acoustic space is a space surrounded by acoustic damping components, a shell, and a sound output outlet. The first microphone is located in front of the sound emission direction of the driver unit that performs audio output based on the noise cancellation signal, and The second microphone is located on the rear side of the driver unit.

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