Sound playback device, signal processing device, signal processing method

Abstract

A sound reproduction device comprises a first microphone used for noise cancellation processing by a feedback method, a second microphone having a sound collecting surface in a direction different from that of the first microphone and used for noise cancellation processing by a feedback method, and a sound signal processing unit that generates a noise canceling signal using a first collected signal collected by the first microphone and a second collected signal collected by the second microphone.

Description

Technology Field

[0001] The present disclosure relates to an audio playback device, a signal processing device, and a signal processing method. In particular, it relates to the generation of a noise canceling signal. Background Technology

[0002] As disclosed in the following patent documents 1, 2, and 3, a noise canceling system is known for headphones or earphones used in portable audio players, etc., which reduces external environmental noise and provides a good playback sound field space with reduced external noise to the listener. Prior art literature

[0003] Japanese Patent Publication No. 2008-122729 Japanese Patent Publication No. 2008-116782 Japanese Patent Publication No. 2008-250270 The problem to be solved

[0004] An example of this type of noise canceling system is an active noise reduction system that performs active noise reduction, and basically has the following configuration.

[0005] In other words, external noise is collected using a microphone acting as an acoustic-to-electrical converter, and a noise-canceling signal is generated from the acoustic signal of the collected noise that is acoustically inverse with the noise. This noise-canceling signal is then combined with an acoustic signal intended for listening, such as music, and reproduced through a speaker. This process reduces noise by acoustically canceling out external noise.

[0006] 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 canceling signal through appropriate filter processing.

[0007] In this disclosure, a more appropriate microphone arrangement is proposed by assuming a case where multiple microphones are used in this manner. means of solving the problem

[0008] The sound reproduction device of the present disclosure comprises a first microphone used for noise cancellation processing by a feedback method, a second microphone having a sound collecting surface in a direction different from that of the first microphone and used for noise cancellation processing by a feedback method, and a sound signal processing unit that generates a noise canceling signal using a first sound collecting signal collected by the first microphone and a second sound collecting signal collected by the second microphone.

[0009] In a configuration equipped with multiple microphones for use in noise cancellation processing by a feedback method, it is easy to make sound collection possible in multiple acoustic spaces within the sound reproduction device.

[0010] In the above-described sound reproduction device, the sound collecting surface of the first microphone may be located closer to the driver unit that performs sound output based on the noise canceling signal than the sound collecting surface of the second microphone.

[0011] This makes it difficult for the spatial transfer function from the driver unit to the sound-collecting surface of the first microphone to change.

[0012] In the above-described sound reproduction device, the sound collecting surface of the first microphone may be positioned opposite the sound discharging direction of the driver unit that performs sound output based on the noise canceling signal.

[0013] This makes it difficult for the spatial transfer function from the driver unit to the sound-collecting surface of the first microphone to change.

[0014] In the above-described sound reproduction device, a driver unit that performs sound output based on the noise canceling signal is disposed, and a housing having a soundproof hole that is soundproofed from the output sound from the driver unit is provided, and the first microphone and the second microphone are disposed within the housing, and the second microphone may be located at a position closer to the soundproof hole than the first microphone.

[0015] By this, the second microphone can collect sound at a position closer to the eardrum than the first microphone.

[0016] In the above-described sound reproduction device, the sound-collecting surface of the second microphone may be positioned so as not to face the sound insulation direction of the driver unit that performs sound output based on the noise canceling signal.

[0017] This makes it easier for the second microphone to pick up noise.

[0018] In the above-described sound reproduction device, at least one acoustic space is located within the housing in the soundproofing direction of the driver unit, and the first microphone and the second microphone may be located in the one acoustic space.

[0019] By this, noise components in an acoustic space where a microphone is placed can be collected with high precision.

[0020] In the above-described sound reproduction device, the first microphone may be positioned such that its sound-collecting surface faces the sound insulation direction of the driver unit, and the second microphone may be positioned such that its sound-collecting surface is oriented in the same direction as the sound insulation direction of the driver unit.

[0021] Due to this, the spatial transfer function from the driver unit to the sound-collecting surface of the first microphone is difficult to change. Additionally, the second microphone makes it easier to collect noise located closer to the eardrum.

[0022] In the above-described sound reproduction device, the first microphone and the second microphone may be placed in different acoustic spaces.

[0023] By this, the noise picked up by the first microphone and the second microphone is made different.

[0024] In the above-described sound reproduction device, a plurality of acoustic spaces are provided within the housing, and the first microphone and the second microphone may be located in different spaces among the plurality of acoustic spaces.

[0025] As a result, the noise picked up by the first microphone and the second microphone becomes different.

[0026] In the above-described sound reproduction device, an acoustic resistance member may be disposed to isolate a first acoustic space where the first microphone is located and a second acoustic space where the second microphone is located.

[0027] By this, for one acoustic space, the transfer function of the space from the driver unit to the microphone can be made into a stable space where it is difficult to change.

[0028] In the above-described sound reproduction device, a driver unit that performs sound output based on the noise canceling signal is disposed, and a housing having a soundproof hole that is soundproofed from the driver unit is provided, and the first sound space may be a space enclosed by the driver unit, the sound resistance member, and the housing, and the second sound space may be a space enclosed by the sound resistance member, the housing, and the soundproof hole.

[0029] As a result, the first acoustic space is composed of a stable space where the spatial transfer function is difficult to change. Additionally, the second acoustic space is composed of a space that is easy to pick up noise located closer to the eardrum.

[0030] In the above-described sound reproduction device, the first microphone may be located on the front side, which is the soundproofing direction of the driver unit that performs sound output based on the noise canceling signal, and the second microphone may be located on the rear side of the driver unit.

[0031] By this, the second microphone located at the rear of the driver unit is able to pick up the sound of the inverse phase of the acoustic output. In addition, the second microphone makes it difficult for the spatial transfer function from the driver unit to the picking surface of the second microphone to change depending on the mounting state of the listener.

[0032] The above-described sound reproduction device comprises a first feedback filter that generates a first noise canceling signal based on a high-frequency component of the first sound collection signal, and a second feedback filter that generates a second noise canceling signal based on a low-frequency component of the second sound collection signal, and the sound signal processing unit may generate the noise canceling signal based on the first noise canceling signal and the second noise canceling signal.

[0033] Since the first microphone is positioned closer to the driver unit than the second microphone, the filter coefficients set in the first FB filter are less likely to be inappropriate than the filter coefficients set in the second FB filter. By doing so, the noise canceling signal based on the first sound collection signal can be made less prone to howling than the noise canceling signal based on the second sound collection signal.

[0034] In the above-described sound reproduction device, the high-frequency component of the first sound collection signal may be extracted by a high-pass filter, a high-shelving filter, or a high-peak EQ filter, and the low-frequency component of the second sound collection signal may be extracted by a low-pass filter, a low-shelving filter, or a low-peak EQ filter.

[0035] By this, a sound collection signal of high-frequency components prone to howling can be input to the feedback loop of the first microphone, where the spatial transfer function from the driver unit to the microphone is difficult to change. Additionally, a sound collection signal of low-frequency components can be input to the feedback loop of the second microphone, which is more prone to picking up noise located closer to the eardrum.

[0036] In the above-described sound reproduction device, a third microphone used for noise cancellation processing by a feedforward method is provided, and the sound signal processing unit may generate the noise canceling signal using the first sound collection signal, the second sound collection signal, and the third sound collection signal collected by the third microphone.

[0037] For example, one can consider providing a third microphone to pick up external sound from the sound playback device.

[0038] The signal processing device of the present disclosure comprises an acoustic signal processing unit that generates a noise canceling signal using a first sound-collected signal collected by a first microphone used for noise canceling processing by a feedback method, and a second sound-collected signal collected by a second microphone used for noise canceling processing by a feedback method, the second microphone having a sound-collecting surface in a direction different from that of the first microphone.

[0039] The signal processing method of the present disclosure generates a noise canceling signal using a first sound-collected signal collected by a first microphone used for noise canceling processing by a feedback method, and a second sound-collected signal collected by a second microphone having a sound-collecting surface in a direction different from that of the first microphone and used for noise canceling processing by a feedback method. Effects of the invention

[0040] According to these signal processing devices or signal processing methods, in a configuration equipped with multiple microphones for use in noise cancellation processing by a feedback method, it is easy to make sound collection occur in multiple acoustic spaces within the sound reproduction device. Brief explanation of the drawing

[0041] FIG. 1 is a block diagram illustrating an example configuration of an audio playback device with a feedback-type noise canceling system in terms of a transfer function. FIG. 2 is a drawing illustrating an earphone of a first embodiment. FIG. 3 is a block diagram of a sound reproduction device of a first embodiment. FIG. 4 is a block diagram of the first DSP of the first embodiment. FIG. 5 is a block diagram of the second DSP of the first embodiment. FIG. 6 is a drawing illustrating headphones of a first embodiment. FIG. 7 is a drawing illustrating an earphone of a second embodiment. FIG. 8 is a drawing illustrating headphones of a second embodiment. FIG. 9 is a drawing illustrating an earphone of a third embodiment. FIG. 10 is a drawing illustrating headphones of a third embodiment. FIG. 11 is a drawing illustrating an earphone of the fourth embodiment. FIG. 12 is a block diagram of a sound reproduction device of a fourth embodiment. FIG. 13 is a block diagram of the third DSP of the fourth embodiment. FIG. 14 is a block diagram of an acoustic reproduction device of the first variant example. FIG. 15 is a drawing illustrating an example of the installation of an acoustic resistance member. FIG. 16 is a drawing illustrating an example of the installation of an acoustic resistance member. FIG. 17 is a drawing illustrating an example of the installation of an acoustic resistance member. FIG. 18 is a drawing illustrating an example of the installation of an acoustic resistance member. Figure 19 is a diagram showing the frequency characteristics of each filter. Specific details for implementing the invention

[0042] The embodiments are described below in the following order.

[0043] <1. Explanation of Noise Canceling Technology>

[0044] <2. First Embodiment>

[0045] <2-1. Configuration of the Sound Playback Device>

[0046] <2-2. Internal Configuration of the Sound Playback Device>

[0047] <2-3. Audio Playback Device as Headphones>

[0048] <3. Second Embodiment>

[0049] <3-1. Audio Playback Device as an Earphone>

[0050] <3-2. Audio Playback Device as Headphones>

[0051] <4. Third Embodiment>

[0052] <4-1. Audio Playback Device as an Earphone>

[0053] <4-2. Audio Playback Device as Headphones>

[0054] <5. Fourth Embodiment>

[0055] <5-1. Configuration of the Sound Playback Device>

[0056] <5-2. Internal Configuration of the Sound Playback Device>

[0057] <6. Variant Example>

[0058] <6-1. First Variation Example>

[0059] <6-2. Second Variation Example>

[0060] <6-3. Others>

[0061] <7. Summary>

[0062] <8. The present technology>

[0063] In addition, the term "sound reproduction device" as used in the description of the embodiment and the claims refers to a device that a listener attaches to their ear to listen to, and includes not only a headset type (headphone) attached to the head, but also a type attached to the outer ear or ear canal called an "earphone."

[0064] <1. Explanation of Noise Canceling Technology>

[0065] A feedback-based noise canceling technology is described. Figure 1 is a block diagram illustrating an example configuration of an audio playback device with a feedback-based noise canceling system in terms of a transfer function.

[0066] In addition, FIG. 1 illustrates only the configuration of the part of the sound reproduction device on one ear of the listener. The configuration of the sound reproduction device for each of the left and right ears is the same as that in FIG. 1.

[0067] The sound reproduction device is provided with a driver unit as an electro-acoustic conversion means for reproducing an acoustic signal which is an electrical signal.

[0068] Then, the sound source signal Sm, which is a signal such as music that the listener intends to play, is supplied to the power amplifier as an output sound signal through an equalizer and an adder. The sound signal through the power amplifier is supplied to the driver unit and sound is reproduced, so that the reproduced sound is soundproofed against the listener's ears.

[0069] In the signal transmission path between the input terminal where the audio signal Sm is input and the left and right ear driver units, an equalizer, an adder, a power amplifier, a microphone, a microphone amplifier, and a noise canceling FB (Feedback) filter are provided.

[0070] In this configuration, in the sound listening environment of the listener, noise N entering the sound listening position of the listener within the sound playback device is reduced by a feedback method among the external noise of the sound playback device, thereby enabling the music to be listened to in a good environment.

[0071] In a feedback-type noise canceling system, noise is collected at an acoustic synthesis location (noise canceling point Pc) that synthesizes the acoustic reproduction sound of the noise and the acoustic signal at the part of the listener's acoustic listening location.

[0072] Accordingly, a noise-collecting microphone is provided at a position capable of collecting noise at a noise-canceling point Pc, which is located inside the housing of the sound reproduction device. Since the sound at the location of this microphone becomes the control point, the noise-canceling point Pc is typically located at a position close to the ear, that is, the front surface of the diaphragm of the driver unit, and a microphone is provided at this position, taking into account the noise attenuation effect.

[0073] Then, the inverse phase component of the noise picked up by the microphone is generated as a noise canceling signal using an FB filter, and the generated noise canceling signal is supplied to a driver unit to reproduce sound, thereby reducing noise that has entered the housing of the sound reproduction device from the outside.

[0074] The analog audio signal captured by the microphone is converted into a digital audio signal by an ADC (Analog-to-digital Converter) through a microphone amplifier. This digital audio signal is then input into a digital filter (FB filter) to generate a feedback-based noise canceling signal.

[0075] A digital filter generates a noise canceling signal with characteristics based on filter coefficients set as parameters from an input digital acoustic signal.

[0076] The generated noise canceling signal is supplied to the adder.

[0077] As described above, the sound source signal Sm that the listener intends to listen to is supplied to the adder through an equalizer. The equalizer performs sound quality correction of the input audio signal.

[0078] The output of this equalizer and the noise canceling signal from the FB filter are combined in an adder and supplied to a driver unit through a power amplifier as an output acoustic signal to reproduce sound.

[0079] In addition, at either the front or rear end of the adder, a Digital-to-Analog Converter (DAC) is provided to convert each signal from a digital signal to an analog signal.

[0080] The reproduced sound includes an acoustic reproduction component based on a noise canceling signal generated in the FB filter. As the acoustic reproduction component based on this noise canceling signal and the noise are acoustically synthesized, the noise is reduced (canceled) at the noise canceling point Pc.

[0081] FIG. 1 illustrates the transfer functions of each part. 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 part, and “-β” represents the transfer function of the filter designed for feedback. Additionally, “H” represents the transfer function of the space from the driver unit to the microphone, and “E” represents the transfer function of the equalizer applied to the sound source signal Sm for listening purposes. Each of the above transfer functions is expressed as a complex number.

[0082] In addition, “N” shown in FIG. 1 is noise that has entered near the microphone position inside the housing of the sound reproduction device from an external noise source, and “P” is the sound pressure reaching the listener’s ear. Furthermore, as for the causes of external noise being transmitted into the housing of the sound reproduction device, for example, cases where it leaks as sound pressure from the gap of the ear pad portion, or cases where sound is transmitted into the housing of the sound reproduction device as a result of the sound reproduction device vibrating upon receiving sound pressure, can be considered.

[0083] The transfer function block of Figure 1 can be expressed by the following (Equation 1).

[0084] (Equation 1)

[0085] P={1 / (1+ADHMβ)}·N+{AHD / (1+ADHMβ)}·ES

[0086] And regarding this (Equation 1), if we focus on the noise, it can be seen that the noise N is attenuated by 1 / (1+ADHMβ). However, for the system of (Equation 1) to operate stably as a noise canceling mechanism in the noise reduction target frequency band, the following (Equation 2) must hold.

[0087] (Equation 2)

[0088] |1 / (1+ADHMβ)|<1

[0089] By setting the filter coefficients of the FB filter to "-β" that satisfies the above (Equation 2), a sufficient noise reduction effect can be obtained.

[0090] <2. First Embodiment>

[0091] <2-1. Configuration of the Sound Playback Device>

[0092] A first embodiment of the sound reproduction device (1) is described with reference to FIG. 2. FIG. 2 is an example of a sound reproduction device (1) as an earphone.

[0093] The sound reproduction device (1) comprises a housing (3) having an internal space (2) formed therein and a driver unit (4) disposed in the internal space (2).

[0094] The driver unit (4) is configured to produce sound output by having a diaphragm (4a).

[0095] In the following description, the soundproofing direction of the driver unit (4) is described as "forward."

[0096] The housing (3) includes a box-shaped part (5) formed in a cylindrical shape with the front-rear direction being axial and open to the front, and a sound guide tube (6) formed in a tubular shape extending forward from the opening at the front of the box-shaped part (5).

[0097] The internal space (2) of the housing (3) is formed by a space surrounded by a box-shaped part (5) and includes a placement space (7) in which each part, such as a driver unit (4), is arranged, and a sound induction space (8) formed by a space surrounded by a sound induction tube (6).

[0098] The front opening of the sound guide tube (6) is formed as a soundproof opening (9) for outputting acoustic output from the driver unit (4) to the outside of the housing (3).

[0099] The driver unit (4) is positioned, for example, in the approximately central part of the front-rear direction in the placement space (7). The placement space (7) is separated by the driver unit (4) into 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).

[0100] In the rear space (7b), for example, a circuit board or battery for driving the driver unit (4) may be stored.

[0101] In the sound reproduction device (1), an earpiece (10) that is detachable from the front is installed on the outer surface of the soundproofing hole (9) in the housing (3). The earpiece (10) is formed from an elastically deformable material such as silicone, rubber, or urethane.

[0102] The sound reproduction device (1) has a plurality of microphones placed in an internal space (2). FIG. 2 is an example in which the sound reproduction device (1) is equipped with two microphones.

[0103] Specifically, the sound playback device (1) is equipped with a first microphone (11) and a second microphone (12) used for noise cancellation processing by a feedback method.

[0104] The first microphone (11) is positioned in the front space (7a) such that the sound collecting surface (11a) faces approximately the diaphragm (4a) of the driver unit (4).

[0105] The second microphone (12) is positioned in the sound induction space (8) such that the sound collecting surface (12a) is oriented differently from the sound collecting surface (11a) of the first microphone (11). Specifically, the second microphone (12) is installed so that the sound collecting surface (12a) faces the central axis of the sound induction tube (6). In other words, the second microphone (12) is positioned so as not to face the diaphragm (4a) of the driver unit (4).

[0106] That is, the first microphone (11) is positioned closer to the driver unit (4) than the second microphone (12).

[0107] Also, the second microphone (12) is positioned closer to the soundproofing hole than the first microphone (11).

[0108] 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 induction space (8), which are different acoustic spaces. That is, the first sound collection signal S1 of the first microphone (11) consists of a signal including noise in the front space (7a). In addition, the second sound collection signal S2 of the second microphone (12) consists of a signal including noise in the sound induction space (8).

[0109] In addition, the second microphone (12) can collect sound at a position closer to the eardrum than the first microphone (11).

[0110] By adopting the above configuration, a noise canceling signal is generated by performing feedback control using the collected sound signals from the first microphone (11) and the second microphone (12).

[0111] The generated noise canceling signal is, for example, added to the sound source signal Sm to be generated as an output signal from the driver unit (4). As the output signal generated in this way is output from the driver unit (4), the noise-reduced playback sound at a predetermined cancel point is heard by the listener.

[0112] <2-2. Internal Configuration of the Sound Playback Device>

[0113] FIG. 3 is a block diagram of the internal configuration of an audio playback device (1). In FIG. 3 and subsequent drawings, only one of the left and right channels for stereo audio signals is shown for the sake of brevity of explanation. It is possible to perform noise cancellation processing on stereo audio by adopting the same configuration as FIG. 3 for the other channel as well.

[0114] In addition, each component part may be shared between the left and right channels.

[0115] A sound source signal Sm as a digital signal is input to the sound playback device (1) from a music / voice source device, such as an audio player not shown, provided externally. The sound source signal Sm is a digital signal, such as music, that a listener intends to listen to.

[0116] The sound reproduction device (1) is equipped with a first amplifier (21A), a first ADC (22A), and a first DSP (Digital Signal Processor) (23A) as parts for processing the first sound collection signal S1 of the first microphone (11).

[0117] Additionally, the sound playback device (1) is equipped with a second amplifier (21B), a second ADC (22B), and a second DSP (23B) as parts for processing the sound collection signal S2 of the second microphone (12).

[0118] In addition, the sound playback device (1) is equipped with an adder (24, 25), an equalizer circuit (26), a DAC (27), and a power amplifier (28).

[0119] The first sound collection signal S1 is sound including noise in the front space (7a) of the diaphragm (4a) of the driver unit (4) as described above.

[0120] The first sound collection signal S1 is amplified in the first amplifier (21A), then converted into a digital signal in the first ADC (22A) and input to the first DSP (23A).

[0121] The first DSP (23A) is equipped with a digital filter for generating a feedback-type noise canceling signal.

[0122] FIG. 4 is a diagram illustrating an example configuration of the first DSP (23A). As shown, the first DSP (23A) is equipped with a High Pass Filter (HPF) (31) and a first FB filter (32).

[0123] HPF (31) is a digital filter that removes low-pass components from the input digital signal from the first ADC (22A).

[0124] The first FB filter (32) is a digital filter for generating a feedback-type digital noise canceling signal.

[0125] That is, the first FB filter (32) generates a first noise canceling signal Snc1 based on the high-frequency component in the first sound collection signal S1.

[0126] The signal generated by the first DSP (23A) is input to the adder (24).

[0127] The second sound collection signal S2 is a sound including noise from the sound induction space (8), which is the internal space of the sound induction tube (6), as described above.

[0128] The second sound collection signal S2 is amplified in the second amplifier (21B), then converted into a digital signal in the second ADC (22B) and input to the second DSP (23B).

[0129] The second DSP (23B) is equipped with a digital filter for generating a feedback-type noise canceling signal.

[0130] FIG. 5 is a diagram illustrating an example configuration of the second DSP (23B). As shown, the second DSP (23B) is equipped with a Low Pass Filter (LPF) (33) and a second FB filter (34).

[0131] The LPF (33) is a digital filter that removes high-frequency components from the input digital signal from the second ADC (22B).

[0132] The second FB filter (34) is a digital filter for generating a feedback-type digital noise canceling signal.

[0133] That is, the second FB filter (34) generates a second noise canceling signal Snc2 based on the low-frequency component of the second sound collection signal S2.

[0134] The signal generated by the second DSP (23B) is input to the adder (24).

[0135] The adder (24) adds and synthesizes the first noise canceling signal Snc1 generated based on the first sound collection signal S1 of the first microphone (11) and the second noise canceling signal Snc2 generated based on the second sound collection signal S2 of the second microphone (12), and outputs the synthesized noise canceling signal Snc to the adder (25).

[0136] For the adder (25), in addition to the synthetic noise canceling signal Snc, a digital signal based on the sound source signal Sm is also input.

[0137] The sound source signal Sm is input to the equalizer circuit (26).

[0138] The equalizer circuit (26) outputs a digital signal obtained by performing equalizing processing for sound quality correction processing or sound quality effect processing on the input sound source signal Sm to the adder (25).

[0139] The equalizer circuit (26) may be configured, for example, within the DSP.

[0140] The adder (25) adds and synthesizes the signal from the synthetic noise canceling signal Snc and the equalizer circuit (26) and outputs it to the DAC (27) as an output sound signal.

[0141] The output signal from the adder (25) is converted into an analog signal in the DAC (27), then amplified in the power amplifier (28) and supplied to the driver unit (4).

[0142] In the driver unit (4), sound output processing based on the input output sound signal is performed. By doing so, the playback sound with reduced noise at a predetermined noise cancellation point is heard by the listener.

[0143] As shown in FIG. 2, the first microphone (11) is positioned so that its sound-collecting surface (11a) faces the diaphragm (4a) of the driver unit (4). By positioning the first microphone (11) in this way, the transfer function of the space from the driver unit (4) to the first microphone (11) is made difficult to change.

[0144] If the transfer function of the space does not change, it becomes possible to generate a noise canceling signal with sufficient noise canceling performance using the filter coefficients set in the first FB filter (32).

[0145] That is, the first noise canceling signal Snc1 generated using the first sound collection signal S1 is capable of fully exhibiting noise canceling performance.

[0146] Also, the second microphone (12) is provided in the sound induction space (8) as shown in FIG. 2, and the transfer function of the space from the driver unit (4) to the second microphone (12) can be changed.

[0147] If the transfer function of the space changes, the filter coefficients set in the second FB filter (34) may not be appropriate, and in that case, howling may occur.

[0148] Howling is generally often caused by high-frequency components of 1 kHz or higher.

[0149] Therefore, for the high-frequency component, we decide to use the first noise canceling signal Snc1 generated using the first microphone (11), which has a spatial transfer function that is difficult to change.

[0150] By doing this, the occurrence of howling caused by high-frequency components can be suppressed.

[0151] In addition, for other low-frequency components, a second noise canceling signal Snc2 is used, which is generated using a second microphone (12) that can collect sound at a position closer to the listener's eardrum.

[0152] By this, it is possible to bring the cancel point close to the eardrum.

[0153] For example, the first noise canceling signal Snc1 is generated based on the high-frequency component of the first sound collection signal S1 extracted by an HPF (31) with a cutoff frequency of 200 Hz.

[0154] In addition, the second noise canceling signal Snc2 is generated based on the low-frequency component of the second sound collection signal S2, which is extracted by an LPF (33) with a cutoff frequency of 200 Hz.

[0155] According to the above configuration, since a composite noise canceling signal Snc is generated by combining a first noise canceling signal Snc1 based on the high-frequency component of a first sound collecting signal S1 and a second noise canceling signal Snc2 based on the low-frequency component of a second sound collecting signal S2, the noise canceling performance at the eardrum position can be improved while suppressing the occurrence of howling.

[0156] In FIG. 3, an example is shown in which a first DSP (23A) and a second DSP (23B) are provided, but a digital filter for the first sound collection signal S1 and a digital filter for the second sound collection signal S2 may be formed within a single DSP.

[0157] In addition, in that case, an equalizer circuit (26) may be formed in the same DSP.

[0158] In addition, Figure 3 illustrates an example where the sound source signal Sm is a digital signal, but it may be an analog signal. In that case, the sound source signal Sm is converted into a digital signal using an ADC and input to the equalizer circuit (26).

[0159] The HPF (31) provided by the first DSP (23A) can be substituted with a high shelving filter or a high peak EQ (equalizer) filter (see FIG. 19).

[0160] In addition, the LPF (33) provided by the second DSP (23B) can be substituted with a low shelving filter or a low peak EQ filter (see FIG. 19).

[0161] In addition, the internal configuration of the sound playback device (1) may not be any other than the configuration shown in FIGS. 3, 4, and 5. For example, at least one of the first FB filter (32) and the second FB filter (34) may be a filter for an analog signal. In that case, the first ADC (22A) or the second ADC (22B) becomes unnecessary.

[0162] In addition, instead of the first DSP (23A) or the second DSP (23B), a CPU (Central Processing Unit) or a hardwired circuit that performs hardwired signal processing may be used.

[0163] In addition, the first microphone (11) or the second microphone (12) may be a digital microphone. In that case, the first ADC (22A) or the second ADC (22B) becomes unnecessary.

[0164] In addition, the HPF (31) shown in FIG. 4 may be provided at the rear end rather than the front end of the first FB filter (32). Also, the HPF (31) may be provided inside the first FB filter (32).

[0165] Likewise, the LPF (33) shown in FIG. 5 may be provided at the rear end of the second FB filter (34) or inside the second FB filter (34).

[0166] The same applies to each subsequent part.

[0167] <2-3. Audio Playback Device as Headphones>

[0168] Referring to FIG. 6, an example in which the configuration of the first embodiment described above is applied to an audio playback device (1A) as a headphone will be explained.

[0169] Also, the same reference numeral is used for the same configuration as the sound playback device (1) as the earphone shown in FIG. 2.

[0170] The sound reproduction device (1A) comprises a housing (3) having an internal space (2) formed therein and a driver unit (4) disposed in the internal space (2).

[0171] The driver unit (4) enables sound output by being equipped with a diaphragm (4a).

[0172] The housing (3) has a base portion (42) in which a placement concave portion (41) is formed for installing a driver unit (4), and an ear pad (43) installed on the front edge of the placement concave portion (41).

[0173] The inner circumference of the front of the pad (43) is formed as a soundproofing element (9).

[0174] The internal space (2) includes a front space (7a) which is a space enclosed by the front surface of the ear pad (43) and driver unit (4) and the soundproofing hole (9), and a rear space (7b) which is a space enclosed by the rear surface of the base part (42) and driver unit (4).

[0175] The sound playback device (1A) is equipped with a first microphone (11) and a second microphone (12) used for noise cancellation processing by a feedback method.

[0176] A protective member (44) is installed in front of the diaphragm (4a) of the driver unit (4), for example, formed in a mesh shape to protect the diaphragm (4a).

[0177] In the protective member (44), a first installation part (44a) in which a first microphone (11) is installed and a second installation part (44b) in which a second microphone (12) is installed are provided approximately in the center.

[0178] The second microphone (12) is positioned so that its sound-collecting surface (12a) faces in a different direction from the sound-collecting surface (11a) of the first microphone (11).

[0179] For example, the first installation part (44a) is formed of a recess that is open to the rear (in the direction of the diaphragm) and the side, and the first microphone (11) is installed so that the sound collecting surface (11a) faces approximately the diaphragm (4a).

[0180] Additionally, the second installation part (44b) is formed as a concave part that is open to the front and side, and a second microphone (12) is installed so that the sound collecting surface (12a) is oriented in the same direction as the sound insulation direction of the driver unit (4).

[0181] The first microphone (11) and the second microphone (12) are both placed in the front space (7a). That is, the first microphone (11) and the second microphone (12) are placed in the same acoustic space.

[0182] The first microphone (11) and the second microphone (12) are placed in the same acoustic space, and the orientation of the sound-collecting surface (11a) of the first microphone (11) and the sound-collecting surface (12a) of the second microphone (12) are different, so that it is possible to collect noise components in the acoustic space where the microphones are placed with high precision.

[0183] Therefore, noise cancellation performance can be improved.

[0184] The block diagram of the internal configuration of the sound playback device (1A) is configured in the same way as in FIG. 3, so the description is omitted.

[0185] Since the sound reproduction device (1A) as a headphone is configured as shown in FIGS. 3 and 6, the first noise canceling signal Snc1 based on the high-frequency component of the first sound collection signal S1 and the second noise canceling signal Snc2 based on the low-frequency component of the second sound collection signal S2 are combined to generate a composite noise canceling signal Snc, thereby suppressing the occurrence of howling and improving the noise canceling performance at the eardrum position.

[0186] <3. Second Embodiment>

[0187] <3-1. Audio Playback Device as an Earphone>

[0188] The sound reproduction device (1B) as an earphone in the second embodiment is equipped with an acoustic resistance member (51) for dividing the internal space (2) into a plurality of acoustic spaces.

[0189] The specific configuration will be explained with reference to FIG. 7. Additionally, configurations similar to the sound reproduction device (1) in the first embodiment shown in FIG. 2 will be given the same reference numerals and will be omitted from description as appropriate.

[0190] The sound reproduction device (1B) comprises a housing (3) having an internal space (2), a driver unit (4) disposed in the internal space (2), a first microphone (11), and a second microphone (12).

[0191] The internal space (2) includes a placement space (7) in which each part is placed, and a sound induction space (8) surrounded by a sound induction tube (6).

[0192] The placement space (7) includes a front space (7a), which is a space in front of the driver unit (4), and a rear space (7b), which is a space behind the driver unit (4).

[0193] The front opening of the sound guide tube (6) is formed as a soundproof opening (9) for outputting acoustic output from the driver unit (4) to the outside of the housing (3).

[0194] The sound reproduction device (1B) is equipped with an acoustic resistance member (51) that isolates both spaces between the front space (7a) and the sound induction space (8).

[0195] That is, the front space (7a) is formed as an acoustically stable space by being surrounded by the box-shaped part (5) of the housing (3), the driver unit (4), and the acoustic resistance member (51). Therefore, the transfer function of the space from the driver unit (4) to the first microphone (11) is made more difficult to change.

[0196] In addition, the sound induction space (8) is composed of a space surrounded by a sound induction tube (6) of the housing (3), an acoustic resistance member (51), and a soundproofing member (9).

[0197] In addition, the division into two acoustic spaces is not limited to cases where the space is completely divided into two spaces by the acoustic resistance member (51), but can also be achieved if the same effect (or a similar effect) is obtained as when the space is completely divided into two acoustic spaces. For example, as shown in FIG. 17 or FIG. 18 described later, the same effect can be obtained even when the space can be considered to be divided into two acoustic spaces by placing the acoustic resistance member (51) in a part between the two acoustic spaces.

[0198] The block diagram of the internal configuration of the sound playback device (1B) is configured in the same way as in Fig. 3.

[0199] By configuring the sound reproduction device (1B) as shown in FIGS. 3 and FIGS. 7, the first noise canceling signal Snc1, which is 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 is a stable space, can further suppress the occurrence of howling and improve the noise canceling performance.

[0200] In addition, the second noise canceling signal Snc2 becomes a signal that enables the cancel point to be brought closer to the eardrum.

[0201] Accordingly, a first noise canceling signal Snc1 based on the high-frequency component of the first sound collection signal S1 and a second noise canceling signal Snc2 based on the low-frequency component of the second sound collection signal S2 are combined to generate a composite noise canceling signal Snc, thereby suppressing the occurrence of howling and further improving the noise canceling performance at the eardrum location.

[0202] <3-2. Audio Playback Device as Headphones>

[0203] Figure 8 illustrates an example of the configuration of an audio playback device (1C) as headphones.

[0204] Also, for configurations similar to the sound playback device (1) shown in FIG. 2, the sound playback device (1A) shown in FIG. 6, and the sound playback device (1B) shown in FIG. 7, the same reference numerals are used and descriptions are omitted accordingly.

[0205] The sound reproduction device (1C) comprises a housing (3) having an internal space (2), a driver unit (4) disposed in the internal space (2), and a first microphone (11) and a second microphone (12) used for noise cancellation processing by a feedback method.

[0206] The driver unit (4) is configured to produce sound output by having a diaphragm (4a).

[0207] The housing (3) has a base portion (42) in which a placement concave portion (41) is formed for installing a driver unit (4), and an ear pad (43) installed on the front edge of the placement concave portion (41).

[0208] The inner circumference of the front of the pad (43) is formed as a soundproofing element (9).

[0209] A protective member (44) is installed in front of the diaphragm (4a) of the driver unit (4), for example, formed in a mesh shape to protect the diaphragm (4a).

[0210] The internal space (2) includes a front space (7a) which is a space enclosed by the front surface of the ear pad (43) and driver unit (4) and the soundproofing hole (9), and a rear space (7b) which is a space enclosed by the rear surface of the base part (42) and driver unit (4).

[0211] In the sound reproduction device (1C), an acoustic resistance member (51) is provided to divide the front space (7a) into two acoustic spaces. Specifically, the front space (7a) is separated by the acoustic resistance member (51) into an inner space (52), which is the space on the driver unit (4) side, and an outer space (53), which is the space on the soundproofing hole (9) side. Additionally, the inner space (52) and the outer space (53) can be identified as the front space (7a) and the sound induction space (8) in the sound reproduction device (1) as an earphone.

[0212] The acoustic resistance member (51) is installed, for example, in the protective member (44).

[0213] The first microphone (11) is installed on the rear side of the protective member (44) such that the sound collecting surface (11a) faces approximately the diaphragm (4a).

[0214] The second microphone (12) is installed on the front surface of the acoustic resistance member (51) such that the sound collecting surface (12a) faces the soundproofing hole (9).

[0215] That is, the first microphone (11) and the second microphone (12) provided by the sound reproduction device (1C) are placed in different acoustic spaces isolated by an acoustic resistance member (51).

[0216] The block diagram of the internal configuration of the sound reproduction device (1C) is configured in the same way as in FIG. 3. That is, in the sound reproduction device (1C), a first noise canceling signal Snc1 is generated based on the high-frequency component of the first sound collection signal S1 of the first microphone (11).

[0217] Therefore, by using the first sound collection signal S1 of the first microphone (11) placed in the inner space (52) which is acoustically stable, a synthetic noise canceling signal Snc is generated, thereby making it possible to further suppress the occurrence of howling.

[0218] In addition, by using the low-frequency component of the second sound collection signal S2 to generate a synthetic noise canceling signal Snc, the noise canceling performance at the eardrum location can be improved.

[0219] <4. Third Embodiment>

[0220] <4-1. Audio Playback Device as an Earphone>

[0221] In the third embodiment, the sound reproduction device (1D) as an earphone is provided with an acoustic resistance member (51) that divides the internal space (2) into a plurality of acoustic spaces, and a second microphone (12) is positioned at the rear of the driver unit (4).

[0222] Specifically, this will be explained with reference to Fig. 9.

[0223] The sound reproduction device (1D) comprises a housing (3) having an internal space (2), a driver unit (4) disposed in the internal space (2), a first microphone (11), and a second microphone (12).

[0224] The internal space (2) includes a placement space (7) in which each part is placed, and a sound induction space (8) surrounded by a sound induction tube (6).

[0225] The placement space (7) includes a front space (7a), which is a space in front of the driver unit (4), and a rear space (7b), which is a space behind the driver unit (4).

[0226] The sound reproduction device (1D) is equipped with an acoustic resistance member (51) that isolates both spaces between the front space (7a) and the sound induction space (8).

[0227] That is, the front space (7a) is formed by the space surrounded by the box-shaped part (5) of the housing (3), the driver unit (4), and the acoustic resistance member (51), thereby becoming an acoustically stable space.

[0228] The first microphone (11) is positioned in the front space (7a) such that the sound collecting surface (11a) is approximately opposite the diaphragm (4a).

[0229] The second microphone (12) is positioned in the rear space (7b) such that the sound collecting surface (12a) does not face the diaphragm (4a).

[0230] The block diagram of the internal configuration of the sound playback device (1D) is configured in the same way as in Fig. 3.

[0231] In the second microphone (12) placed in the rear space (7b), sound pressure that is inversely phase to the sound pressure emitted forward from the diaphragm (4a) and noise that has entered through the housing (3) can be collected. In addition, the signal collected by the second microphone (12) can be configured to be less affected by changes in the transfer function of the space from the driver unit to the microphone.

[0232] Therefore, by using the second sound collection signal S2 from the second microphone (12) to generate a synthetic noise canceling signal Snc, the noise canceling performance can be improved.

[0233] In addition, in this example, although an example is shown 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), the first microphone (11) may be placed in the rear space (7b) and the second microphone (12) may be placed in the sound induction space (8).

[0234] <4-2. Audio Playback Device as Headphones>

[0235] A sound reproduction device (1E) as a headphone in the third embodiment will be described with reference to FIG. 10.

[0236] Also, regarding configurations similar to the various sound reproduction devices described above, such as the sound reproduction device (1) shown in FIG. 2 or the sound reproduction device (1A) shown in FIG. 6, the same reference numerals are used and descriptions are omitted accordingly.

[0237] The sound reproduction device (1E) comprises a housing (3) having an internal space (2), a driver unit (4) disposed in the internal space (2), and a first microphone (11) and a second microphone (12) used for noise cancellation processing by a feedback method.

[0238] The driver unit (4) is configured to produce sound output by having a diaphragm (4a).

[0239] The housing (3) is equipped with a base part (42) and an ear pad (43). The inner circumference of the front of the ear pad (43) is formed as a soundproofing part (9).

[0240] A protective member (44) is installed in front of the diaphragm (4a) of the driver unit (4).

[0241] The first microphone (11) is positioned in the front space (7a). Specifically, the first microphone (11) is installed on the rear surface of the protective member (44) such that the sound collecting surface (11a) faces approximately the diaphragm (4a).

[0242] The second microphone (12) is positioned in the rear space (7b). Specifically, the second microphone (12) is installed in the housing (3) such that the sound collecting surface (12a) is oriented differently from the sound collecting surface (11a) of the first microphone (11).

[0243] That is, the first microphone (11) and the second microphone (12) provided by the sound playback device (1E) are placed in different acoustic spaces.

[0244] In the second microphone (12) placed in the rear space (7b), sound pressure opposite to that emitted forward from the diaphragm (4a) and noise entering through the housing (3) can be collected.

[0245] Therefore, by using the second sound collection signal S2 from the second microphone (12) to generate a synthetic noise canceling signal Snc, the noise canceling performance can be improved.

[0246] <5. Fourth Embodiment>

[0247] <5-1. Configuration of the Sound Playback Device>

[0248] FIG. 11 is an audio playback device (1F) as an earphone in the fourth embodiment. The audio playback device (1F) in the fourth embodiment is equipped with a third microphone (61) for generating a feedforward type noise canceling signal.

[0249] Specifically, the configuration of the sound playback device (1F) will be explained with reference to FIG. 11.

[0250] The sound reproduction device (1F) comprises a housing (3) having an internal space (2), a driver unit (4) disposed in the internal space (2), a first microphone (11) and a second microphone (12) used for noise cancellation processing by a feedback method, and a third microphone (61) used for noise cancellation processing by a feedforward method.

[0251] The internal space (2) includes a placement space (7) in which each part is placed, and a sound induction space (8) surrounded by a sound induction tube (6).

[0252] The placement space (7) includes a front space (7a), which is a space in front of the driver unit (4), and a rear space (7b), which is a space behind the driver unit (4).

[0253] The first microphone (11) is positioned in the front space (7a) such that the sound collecting surface (11a) is approximately opposite the diaphragm (4a).

[0254] The second microphone (12) is positioned in the sound induction space (8) such that the sound collecting surface (12a) faces in a different direction from the sound collecting surface (11a) of the first microphone (11).

[0255] The third microphone (61) is installed in the housing (3) such that the sound collecting surface (61a) is located in the external space so as to be able to collect sound from outside the sound playback device (1F).

[0256] By doing so, it is possible to combine feedback-based noise cancellation processing and feed-forward-based noise cancellation processing, thereby improving noise cancellation performance.

[0257] Additionally, the acoustic playback device (1F) may be equipped with an acoustic resistance member (51) that isolates both spaces between the front space (7a) and the sound induction space (8).

[0258] By this, the front space (7a) is formed into an acoustically stable space surrounded by the box-shaped part (5) of the housing (3), the driver unit (4), and the acoustic resistance member (51).

[0259] <5-2. Internal Configuration of the Sound Playback Device>

[0260] FIG. 12 is a block diagram of the internal configuration of a sound playback device (1F).

[0261] The sound reproduction device (1F) is equipped with a first amplifier (21A), a first ADC (22A), and a first DSP (23A) as parts for processing the first sound collection signal S1 of the first microphone (11).

[0262] Additionally, the sound playback device (1F) is equipped with a second amplifier (21B), a second ADC (22B), and a second DSP (23B) as parts for processing the sound collection signal S2 of the second microphone (12).

[0263] Additionally, the sound playback device (1) is equipped with a third amplifier (21C), a third ADC (22C), and a third DSP (23C) as parts for processing the sound collection signal S3 of the third microphone (61).

[0264] The sound playback device (1F) is equipped with an adder (24, 25), an equalizer circuit (26), a DAC (27), and a power amplifier (28), and further includes an adder (62).

[0265] The first sound collection signal S1 is sound including noise in the front space (7a) of the diaphragm (4a) of the driver unit (4) as described above.

[0266] The first sound collection signal S1 is amplified in the first amplifier (21A), then converted into a digital signal in the first ADC (22A) and input to the first DSP (23A).

[0267] The first DSP (23A) is equipped with a digital filter for generating a feedback-type noise canceling signal (see FIG. 4).

[0268] The signal generated by the first DSP (23A) is input to the adder (24).

[0269] The second sound collection signal S2 is a sound including noise from the sound induction space (8), which is the internal space of the sound induction tube (6), as described above.

[0270] The second sound collection signal S2 is amplified in the second amplifier (21B), then converted into a digital signal in the second ADC (22B) and input to the second DSP (23B).

[0271] The second DSP (23B) is equipped with a digital filter for generating a feedback-type noise canceling signal (see FIG. 5).

[0272] The signal generated by the second DSP (23B) is input to the adder (24).

[0273] The adder (24) adds and synthesizes the first noise canceling signal Snc1 generated based on the first sound collection signal S1 of the first microphone (11) and the second noise canceling signal Snc2 generated based on the second sound collection signal S2 of the second microphone (12) and outputs the result to the adder (62).

[0274] The third sound collection signal S3 is sound collected including noise from the external space of the sound reproduction device (1F).

[0275] The third sound collection signal S3 is amplified in the third amplifier (21C), then converted into a digital signal in the third ADC (22C) and input to the third DSP (23C).

[0276] The third DSP (23C) is equipped with a digital filter for generating a feed-forward noise canceling signal. Specifically, as shown in FIG. 13, it is equipped with a third FF filter (63).

[0277] The third FF filter (63) is a digital filter for generating a feed-forward digital noise canceling signal. That is, the third FF filter (63) generates a third noise canceling signal Snc3 based on the third sound collection signal S3.

[0278] The third noise canceling signal Snc3 generated by the third DSP (23C) is input to the adder (62).

[0279] The adder (62) adds and synthesizes the first noise canceling signal Snc1 generated based on the first sound collection signal S1 of the first microphone (11), the second noise canceling signal Snc2 generated based on the second sound collection signal S2 of the second microphone (12), and the third noise canceling signal Snc3 generated based on the third sound collection signal S3 of the third microphone (61), and outputs the synthesized noise canceling signal Snc to the adder (25).

[0280] For the adder (25), in addition to the synthetic noise canceling signal Snc, a digital signal based on the sound source signal Sm is also input.

[0281] The sound source signal Sm is input to the equalizer circuit (26).

[0282] The equalizer circuit (26) outputs a digital signal obtained by performing equalizing processing for sound quality correction processing or sound quality effect processing on the input sound source signal Sm to the adder (25).

[0283] The equalizer circuit (26) may be configured, for example, within the DSP.

[0284] The adder (25) adds and synthesizes the signal from the synthetic noise canceling signal Snc and the equalizer circuit (26) and outputs it to the DAC (27) as an output sound signal.

[0285] The output signal from the adder (25) is converted into an analog signal in the DAC (27), then amplified in the power amplifier (28) and supplied to the driver unit (4).

[0286] In the driver unit (4), sound output processing based on the input output sound signal is performed. By doing so, the playback sound with reduced noise at a predetermined noise cancellation point is heard by the listener.

[0287] As shown in FIG. 11, the first microphone (11) is positioned so that the sound collecting surface (11a) faces the diaphragm (4a) of the driver unit (4), so the first noise canceling signal Snc1 can suppress the occurrence of howling.

[0288] In addition, by using a second sound collection signal S2 from a second microphone (12) in which the sound collection surface (12a) is oriented differently from the first microphone (11), it is possible to bring the cancellation point closer to the eardrum.

[0289] In addition, since the sound collecting surface (61a) is configured to collect noise from the external space of the sound reproduction device (1F), it is possible to perform noise cancellation processing by a feed-forward method.

[0290] Noise cancellation performance can be improved by using the third sound collection signal S3 by the third microphone (61).

[0291] In FIG. 12, an example is shown in which a first DSP (23A), a second DSP (23B), and a third DSP (23C) are provided, but a digital filter for a first sound collection signal S1, a digital filter for a second sound collection signal S2, and a digital filter for a third sound collection signal S3 may be formed within a single DSP.

[0292] In addition, in that case, an equalizer circuit (26) may be formed in the same DSP.

[0293] In addition, Figure 3 illustrates an example where the sound source signal Sm is a digital signal, but it may be an analog signal. In that case, the sound source signal Sm is converted into a digital signal using an ADC and input to the equalizer circuit (26).

[0294] In addition, the sound reproduction device (1F) as a fourth embodiment may be a sound reproduction device as a headphone equipped with a third microphone (61), and in that case, the same effect can be obtained.

[0295] <6. Variant Example>

[0296] <6-1. First Variation Example>

[0297] In each of the examples described above, an example was explained in which a digital filter for generating a noise canceling signal is provided for each of the first sound collection signal S1 and the second sound collection signal S2.

[0298] That is, as described in FIGS. 3, 4 and 5, in the sound reproduction device (1), a first FB filter (32) is provided as a digital filter for generating a first noise canceling 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 canceling signal Snc2 using a second sound collection signal S2.

[0299] To reduce the computational load of digital filter processing, only one digital filter is required to generate the synthetic noise canceling signal Snc.

[0300] Specifically, with reference to FIG. 14, the internal configuration of an acoustic playback device (1G) having only one digital filter for generating a synthetic noise canceling signal Snc is described.

[0301] The sound reproduction device (1G) is equipped with a first amplifier (21A), a first ADC (22A), and an HPF (71) as parts for processing the first sound collection signal S1 of the first microphone (11). That is, the sound reproduction device (1G) is not equipped with a first DSP that performs digital filter processing on the first sound collection signal S1.

[0302] The first sound collection signal S1 is amplified in the first amplifier (21A), converted into a digital signal in the first ADC (22A), and the low-frequency component is removed in the HPF (71) and input to the adder (73).

[0303] The sound reproduction device (1G) is equipped with a second amplifier (21B), a second ADC (22B), and an LPF (72) as components for processing the second sound collection signal S2 of the second microphone (12). That is, the sound reproduction device (1G) is not equipped with a second DSP that performs digital filter processing on the second sound collection signal S2.

[0304] The second sound collection signal S2 is amplified in the second amplifier (21B), converted into a digital signal in the second ADC (22B), and also has its high-frequency components removed in the LPF (72) and input to the adder (73).

[0305] The adder (73) adds and synthesizes the high-frequency component of the first sound collection signal S1 of the first microphone (11) and the low-frequency component of the second sound collection signal S2 of the second microphone (12), and outputs the result to a digital filter, FB filter (74), for generating a noise canceling signal.

[0306] The FB filter (74) performs digital filter processing to generate a noise canceling signal Snc' based on the additively synthesized sound collection signal.

[0307] The generated noise canceling signal Snc' can be considered as the aforementioned synthetic noise canceling signal Snc.

[0308] The adder (25) adds and synthesizes the noise canceling signal Snc' and the signal from the equalizer circuit (26) and outputs it to the DAC (27) as an output sound signal.

[0309] The DAC (27) converts the input signal from the adder (25) into an analog signal and outputs it to the power amplifier (28).

[0310] The power amplifier (28) amplifies the input signal and supplies it to the driver unit (4).

[0311] In the driver unit (4), sound output processing based on the input output sound signal is performed.

[0312] In addition, the HPF (71) shown in FIG. 14 may be provided at the front end rather than the rear end of the first ADC (22A). That is, filter processing may be performed on the analog signal.

[0313] Likewise, the LPF (72) may be provided at the front end of the second ADC (22B).

[0314] In addition, the HPF (71) can be replaced with a high shelving filter or a high peak EQ filter. Also, the LPF (72) can be replaced with a low shelving filter or a low peak EQ filter.

[0315] In addition, the configuration may be one in which HPF (71) or LPF (72) is not provided and only FB filter (74) is provided.

[0316] <6-2. Second Variation Example>

[0317] In the second embodiment, an example was described in which an acoustic resistance member (51) is provided in the acoustic playback device (1B, 1C).

[0318] Here, the installation method of the acoustic resistance member (51) is explained by exemplifying a headphone-type sound playback device (1C).

[0319] The first example of the installation of an acoustic resistance member (51) to a protective member (44) is illustrated in FIG. 15. The acoustic resistance member (51) (illustrated by diagonal hatching) may be installed across the entire surface in front of the protective member (44).

[0320] By this, the space in front of the acoustic resistance member (51) (e.g., outer space (53)) and the space behind it (e.g., inner space (52)) can be acoustically separated. Thus, the space behind can be made acoustically more stable, thereby suppressing the occurrence of howling.

[0321] A second example of the installation of an acoustic resistance member (51) into a protective member (44) is shown in FIG. 16. The acoustic resistance member (51) (shown by diagonal hatching) may be installed from the front to cover approximately the center of the protective member (44).

[0322] In this case, it is preferable to position the first microphone (11) in the center of the acoustic resistance member (51).

[0323] A third example of the installation of an acoustic resistance member (51) into a protective member (44) is illustrated in FIG. 17. The acoustic resistance member (51) (illustrated by diagonal hatching) may be installed from the front to cover the upper half, lower half, right half, or left half of the protective member (44).

[0324] In addition, in that case, it is preferable that the acoustic resistance member (51) be positioned so as to be offset from the portion covered by the acoustic resistance member (51) with respect to the central portion of the protective member (44).

[0325] A fourth example of the installation of an acoustic resistance member (51) into a protective member (44) is illustrated in FIG. 18. The acoustic resistance member (51) (illustrated by diagonal hatching) may be installed from the front to cover the central part extending from the top to the bottom of the protective member (44).

[0326] In addition, in that case, it is preferable to position the first microphone (11) in the center of the acoustic resistance member (51).

[0327] In addition to the configuration in which an acoustic resistance member (51) is installed across the entire surface of a protective member (44) as shown in FIG. 15, even with the configuration as shown in FIG. 16, FIG. 17 and FIG. 18, the rear space can be made acoustically stable, so the effect of suppressing howling can be obtained.

[0328] <6-3. Others>

[0329] In addition, while headphones or earphones were used as examples of sound playback devices in each of the examples described above, other examples can also be considered. For instance, the configuration described above can also be applied to noise canceling signals generated to perform noise canceling processing in a space of a certain size, such as a room.

[0330] That is, the first MC and the second MC used for FB control are provided indoors. In this case, the second MC is positioned closer to the window or door than the first MC.

[0331] In addition, a third MC used for FF control may be provided outside the room.

[0332] In this way, when watching music or the like in a room as an acoustic space, noise is reduced, and a space suitable for viewing can be provided.

[0333] <7. Summary>

[0334] In the above-described sound reproduction device (1 (1A, 1B, 1C, 1D, 1E, 1G)) such as headphones or earphones, there is a first microphone (11) used for noise cancellation processing by a feedback method, a second microphone (12) having a sound collecting surface in a direction different from the first microphone (11) and used for noise cancellation processing by a feedback method, and an acoustic signal processing unit (first DSP (23A), second DSP (23B), etc.) that generates a noise canceling signal using a first sound collecting signal S1 collected by the first microphone (11) and a second sound collecting signal S2 collected by the second microphone (12).

[0335] In a configuration equipped with multiple microphones for use in noise cancellation processing by a feedback method, it is easy to perform sound collection in multiple acoustic spaces within the sound reproduction device (1) (e.g., the space in front of the driver unit (4) (7a) and the space within the sound guide tube (sound guide space (8))).

[0336] By using multiple microphones in the feedback method, the noise cancellation effect can be enhanced. By changing the sound collection direction of each microphone, acoustic signals containing noise can be appropriately collected in multiple spaces, making it suitable for improving the noise cancellation effect of the feedback method.

[0337] As described in the first embodiment (Fig. 2), in the sound reproduction device (1), the sound collecting surface (11a) of the first microphone (11) may be located closer to the driver unit (4) that performs sound output based on the noise canceling signal than the sound collecting surface (12a) of the second microphone (12).

[0338] By this, the transfer function of the space from the driver unit (4) to the sound collecting surface (11a) of the first microphone (11) is made difficult to change.

[0339] Therefore, it is possible to generate a first noise canceling signal Snc1 with sufficient noise canceling performance using the filter coefficients set in the first FB filter (32). That is, noise canceling performance can be improved by applying the first noise canceling signal Snc1 generated by the sound collection signal of the first microphone (11).

[0340] As described in the first embodiment (Fig. 2), in the sound reproduction device (1), the sound collecting surface (11a) of the first microphone (11) may be positioned facing the soundproofing direction (forward) of the driver unit (4) that performs sound output based on the noise canceling signal.

[0341] By this, the transfer function of the space from the driver unit (4) to the sound collecting surface (11a) of the first microphone (11) is made difficult to change.

[0342] Therefore, it is possible to generate a first noise canceling signal Snc1 with sufficient noise canceling performance using the filter coefficients set in the first FB filter (32). That is, noise canceling performance can be improved by applying the first noise canceling signal Snc1 generated by the sound collection signal of the first microphone (11).

[0343] As described in the first embodiment (Fig. 2), in the sound reproduction device (1), a driver unit (4) that performs sound output based on a noise canceling signal is arranged, and a housing (3) having a soundproof hole (9) that is soundproofed from the output sound from the driver unit (4) is provided, and a first microphone (11) and a second microphone (12) are arranged in the housing (3), and the second microphone (12) may be located closer to the soundproof hole (9) than the first microphone (11).

[0344] By this, the second microphone (12) can collect sound at a position closer to the eardrum than the first microphone (11).

[0345] Therefore, the cancellation point is positioned closer to the eardrum, which can improve noise cancellation performance.

[0346] In the sound reproduction device (1) as described in the first embodiment (Fig. 2, Fig. 6), the second embodiment (Fig. 7, Fig. 8), the third embodiment (Fig. 9, Fig. 10), and the fourth embodiment (Fig. 11), the sound collecting surface (12a) of the second microphone (12) may be positioned so as not to face the soundproofing direction (front) of the driver unit (4) that performs sound output based on the noise canceling signal.

[0347] By this, the second microphone (12) makes it easier to pick up noise.

[0348] Therefore, noise cancellation performance can be improved.

[0349] As described in the first embodiment (Fig. 6), in the sound reproduction device (1), at least one acoustic space is located in the soundproofing direction of the driver unit (4) within the housing (3), and the first microphone (11) and the second microphone (12) may be located in one acoustic space.

[0350] By this, noise components in an acoustic space where a microphone is placed can be collected with high precision.

[0351] Therefore, it is possible to set the filter coefficients more appropriately, thereby improving noise cancellation performance.

[0352] Furthermore, it eliminates the need for components or the like to divide the acoustic space into multiple sections. This allows for a reduction in manufacturing costs. Additionally, by reducing the number of parts, the number of assembly processes can be reduced.

[0353] In the sound reproduction device (1) as described in the first embodiment (Fig. 6), the second embodiment (Fig. 8), and the third embodiment (Fig. 10), the first microphone (11) may be positioned so that its sound-collecting surface (11a) faces the soundproofing direction of the driver unit (4), and the second microphone (12) may be positioned so that its sound-collecting surface (12a) is oriented in the same direction as the soundproofing direction of the driver unit (4).

[0354] By this, the transfer function of the space from the driver unit (4) to the sound-collecting surface (11a) of the first microphone (11) is difficult to change. Additionally, the second microphone (12) makes it easier to collect noise located closer to the eardrum.

[0355] Therefore, by using both the first sound collection signal S1 of the first microphone (11) and the second sound collection signal S2 of the second microphone (12) to generate a noise canceling signal, it is possible to improve noise canceling performance while suppressing the occurrence of howling.

[0356] In the sound reproduction device (1) as described in the first embodiment (Fig. 2), the second embodiment (Fig. 7, Fig. 8), or the third embodiment (Fig. 9, Fig. 10), the first microphone (11) and the second microphone (12) may be placed in different acoustic spaces.

[0357] By this, the noise picked up by the first microphone (11) and the second microphone (12) becomes different.

[0358] Therefore, it is possible to improve noise cancellation performance by generating a noise canceling signal based on both the first sound collection signal S1 of the first microphone (11) and the second sound collection signal S2 of the second microphone (12).

[0359] In the sound reproduction device (1) as described in the first embodiment (Fig. 2), the second embodiment (Fig. 7, Fig. 8), or the third embodiment (Fig. 9, Fig. 10), a plurality of acoustic spaces are provided within the housing (3), and the first microphone (11) and the second microphone (12) may be located in different spaces among the plurality of acoustic spaces.

[0360] By this, both the first microphone (11) and the second microphone (12) are placed within the housing (3). Additionally, the noise picked up by the first microphone (11) and the second microphone (12) becomes different.

[0361] Therefore, sound collection signals from different locations within the housing can be obtained, thereby improving noise cancellation performance.

[0362] As described in the second embodiment (Fig. 7, Fig. 8), in the sound reproduction device (1), an acoustic resistance member (51) may be arranged to isolate the first acoustic space (front space (7a), inner space (52)) where the first microphone (11) is located and the second acoustic space (sound induction space (8)) where the second microphone (12) is located.

[0363] By this, for one acoustic space (front space (7a)), the transfer function of the space from the driver unit (4) to the microphone (first microphone (11)) can be made into a stable space that is difficult to change.

[0364] Therefore, a high noise cancellation effect can be obtained by using the set filter coefficients.

[0365] As described in the second embodiment (Fig. 7, Fig. 8), the sound reproduction device (1) may be provided with a driver unit (4) that performs sound output based on a noise canceling signal, and a housing (3) having a soundproofing hole (9) that is soundproofed from the output sound from the driver unit (4), and the first sound space (front space (7a)) may be a space surrounded by the driver unit (4), the sound resistance member (51), and the housing (3), and the second sound space (sound induction space (8)) may be a space surrounded by the sound resistance member (51), the housing (3), and the soundproofing hole (9).

[0366] As a result, the first acoustic space is composed of a stable space where the spatial transfer function is difficult to change. Additionally, the second acoustic space is composed of a space that is easy to pick up noise located closer to the eardrum.

[0367] By generating a first noise canceling signal Snc1 using a first sound collection signal S1 of a first microphone (11) placed in a first acoustic space (such as the front space (7a) in FIG. 2 or the inner space (52) in FIG. 8) that is acoustically stable, the filter coefficients set in the first FB filter (32) can be appropriately set to have high noise canceling performance.

[0368] In addition, sound playback devices such as earphones or headphones may deform depending on the usage conditions. In such cases, as the spatial transfer function changes, the set filter coefficients may become inappropriate, potentially causing howling to occur. Even in such cases, the first acoustic space is shielded from the outside by the acoustic resistance member (51), thereby maintaining an acoustically stable state, ensuring that the filter coefficients are set appropriately and suppressing howling.

[0369] However, in the case of a microphone (first microphone (11)) placed in a stable space, it may not be able to sufficiently collect noise near the point where the noise canceling effect is intended to be exerted (i.e., near the eardrum). If the noise collection is insufficient, the generated noise canceling signal may not be appropriate, and the active noise canceling effect at the eardrum location may be reduced.

[0370] According to the present configuration, a second noise canceling signal Snc2 is generated using a second sound collection signal S2 of a second microphone (12) placed in a second acoustic space different from the first acoustic space (such as the sound induction space (8) in FIG. 2 or the outer space (53) in FIG. 8), so high noise canceling performance can be achieved while suppressing howling.

[0371] As described in the third embodiment (Fig. 9, Fig. 10), in the sound reproduction device (1), the first microphone (11) may be located on the front side, which is the soundproofing direction of the driver unit (4) that performs sound output based on a noise canceling signal, and the second microphone (12) may be located on the rear side of the driver unit (4).

[0372] By this, for example, the second microphone (12) located at the rear of the driver unit (4) can pick up the sound of the inverse phase of the acoustic output. In addition, the second microphone (12) makes it difficult for the transfer function of the space from the driver unit (4) to the sound-picking surface (12a) of the second microphone (12) to change according to the mounting state of the listener.

[0373] At this time, the second microphone (12) collects noise that is not completely removed in the noise canceling signal generated based on the first sound collection signal S1 of the first microphone (11).

[0374] Therefore, by generating a noise canceling signal based on the first sound collection signal S1 of the first microphone (11) as well as the second sound collection signal S2 of the second microphone (12), high noise canceling performance can be achieved.

[0375] As described in the first embodiment (Figs. 4 and 5), the sound reproduction device (1) is provided with a first feedback filter (first FB filter (32)) that generates a first noise canceling signal Snc1 based on a high-frequency component of a first sound collection signal S1, and a second feedback filter (second FB filter (34)) that generates a second noise canceling signal Snc2 based on a low-frequency component of a second sound collection signal S2, and the sound signal processing unit may generate a noise canceling signal based on the first noise canceling signal Snc1 and the second noise canceling signal Snc2.

[0376] Since the first microphone (11) is positioned closer to the driver unit (4) than the second microphone (12), the filter coefficient set in the first FB filter (32) is less likely to be inappropriate than the filter coefficient set in the second FB filter (34). By this, the first noise canceling signal Snc1 based on the first sound collection signal S1 can be made less likely to cause howling than the second noise canceling signal Snc2 based on the second sound collection signal S2.

[0377] Accordingly, for high-frequency components prone to howling, a first noise canceling signal Snc1 is generated by using a first sound collection signal S1, which makes howling less likely to occur, and for low-frequency components less prone to howling, a second noise canceling signal Snc2 is generated by using a second sound collection signal S2, which improves noise canceling performance. By generating noise canceling signals using these, noise canceling performance can be improved while suppressing the occurrence of howling.

[0378] As described in the first embodiment (Figs. 4 and 5), in the sound reproduction device (1), the high-frequency component of the first collected signal S1 may be extracted by a high-pass filter HPF (31), a high shelving filter, or a high-peak EQ filter, and the low-frequency component of the second collected signal S2 may be extracted by a low-pass filter LPF (33), a low shelving filter, or a low-peak EQ filter.

[0379] By this, a high-frequency component sound collection signal that is prone to howling can be input to the feedback loop of the first microphone (11), where the transfer function of the space from the driver unit (4) to the microphone is difficult to change. Additionally, a low-frequency component sound collection signal can be input to the feedback loop of the second microphone (12), where noise at a location closer to the eardrum is easy to collect.

[0380] Therefore, the occurrence of howling can be suppressed. In addition, by removing the low-frequency component of the first sound collection signal S1, the noise cancellation performance based on the second sound collection signal S2 can be improved.

[0381] As described in the fourth embodiment (Fig. 11), the sound reproduction device (1) is equipped with a third microphone (61) used for noise cancellation processing by a feedforward method, and the sound signal processing unit (first DSP (23A), second DSP (23B), third FF filter (63), etc.) may generate a noise canceling signal 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).

[0382] For example, one can consider providing a third microphone (61) to pick up external sound from the sound playback device (1F).

[0383] By using the third sound collection signal S3 by the third microphone (61) as described above, noise cancellation performance can be improved.

[0384] As described in the various embodiments above, the signal processing device is equipped with an acoustic signal processing unit (first DSP (23A), second DSP (23B), etc.) that generates a noise canceling signal using a first collected signal S1 collected by a first microphone (11) used for noise canceling processing by a feedback method, and a second collected signal S2 collected by a second microphone (12) used for noise canceling processing by a feedback method, which has a collecting surface in a direction different from that of the first microphone (11).

[0385] In addition, the signal processing method executed by the signal processing device is a method of generating a noise canceling signal using a first sound-collected signal S1 collected by a first microphone (11) used for noise canceling processing by a feedback method, and a second sound-collected signal S2 collected by a second microphone (12) which has a sound-collecting surface in a direction different from that of the first microphone (11) and is used for noise canceling processing by a feedback method.

[0386] By means of such a signal processing device and signal processing method, it is easy to make sound collection possible in a plurality of acoustic spaces within the sound reproduction device (1) (e.g., the space in front of the driver unit (4) (7a) and the space within the sound guide tube (sound guide space (8))), and by using a plurality of microphones used in the feedback method, it is possible to contribute to the improvement of the noise cancellation effect. By changing the sound collection direction of each microphone, sound collection of acoustic signals containing noise can be appropriately performed in the plurality of spaces. By doing so, it is possible to improve the noise cancellation effect by the feedback method.

[0387] Furthermore, the effects described in this specification are merely examples and are not limited thereto, and other effects may also be present.

[0388] In addition, each of the examples described above can be combined in any way possible, as long as the combination is not impossible.

[0389] <8. The present technology>

[0390] In addition, the headphone device of the present technology may also adopt the following configuration.

[0391] (1)

[0392] A first microphone used for noise cancellation processing by a feedback method, and

[0393] A second microphone having a sound-collecting surface in a direction different from the first microphone and used for noise cancellation processing by a feedback method, and

[0394] A sound signal processing unit having a first sound collected by the first microphone and a second sound collected by the second microphone to generate a noise canceling signal.

[0395] Sound playback device.

[0396] (2)

[0397] The sound-collecting surface of the first microphone is located closer to the driver unit that performs acoustic output based on the noise canceling signal than the sound-collecting surface of the second microphone.

[0398] The sound reproduction device described in (1) above.

[0399] (3)

[0400] The sound-collecting surface of the first microphone is positioned opposite the sound insulation direction of the driver unit that performs acoustic output based on the noise canceling signal.

[0401] A sound reproduction device described in any one of (1) to (2) above.

[0402] (4)

[0403] A driver unit that performs acoustic output based on the above noise canceling signal is disposed therein, and a housing having a soundproof hole that is soundproofed from the output sound from the driver unit is provided.

[0404] The first microphone and the second microphone are disposed within the housing, and

[0405] The second microphone is located at a position closer to the soundproofing hole than the first microphone,

[0406] A sound reproduction device described in any one of (1) to (3) above.

[0407] (5)

[0408] The sound-collecting surface of the second microphone is positioned so as not to face the sound insulation direction of the driver unit that performs acoustic output based on the noise canceling signal.

[0409] A sound reproduction device described in any one of (1) to (4) above.

[0410] (6)

[0411] In the above housing, at least one acoustic space is located in the soundproofing direction of the driver unit, and

[0412] The first microphone and the second microphone are located in the one acoustic space,

[0413] The sound reproduction device described in (4) above.

[0414] (7)

[0415] The first microphone is positioned such that its sound-collecting surface faces the sound insulation direction of the driver unit, and

[0416] The second microphone is positioned so that its sound-collecting surface is oriented in the same direction as the sound insulation direction of the driver unit.

[0417] The sound reproduction device described in (6) above.

[0418] (8)

[0419] The first microphone and the second microphone are placed in different acoustic spaces,

[0420] A sound reproduction device described in any one of (1) to (5) above.

[0421] (9)

[0422] A plurality of acoustic spaces are provided within the above housing, and

[0423] The first microphone and the second microphone are located in different spaces within the plurality of acoustic spaces,

[0424] A sound reproduction device described in either (4) or (6) above.

[0425] (10)

[0426] An acoustic resistance member is disposed to isolate a first acoustic space where the first microphone is located and a second acoustic space where the second microphone is located,

[0427] The sound reproduction device described in (8) above.

[0428] (11)

[0429] A driver unit that performs acoustic output based on the above noise canceling signal is disposed therein, and a housing having a soundproof hole that is soundproofed from the output sound from the driver unit is provided.

[0430] The first acoustic space is composed of a space enclosed by the driver unit, the acoustic resistance member, and the housing.

[0431] The second acoustic space is a space enclosed by the acoustic resistance member, the housing, and the soundproofing member.

[0432] The sound reproduction device described in (10) above.

[0433] (12)

[0434] The first microphone is located on the front side, which is the soundproofing direction of the driver unit that performs acoustic output based on the noise canceling signal, and

[0435] The second microphone is located on the rear side of the driver unit,

[0436] A sound reproduction device described in any one of (1) to (11) above.

[0437] (13)

[0438] A first feedback filter that generates a first noise canceling signal based on the high-frequency component of the first sound collection signal, and

[0439] A second feedback filter is provided to generate a second noise canceling signal based on the low-frequency component of the second sound collection signal.

[0440] The above acoustic signal processing unit generates the noise canceling signal based on the first noise canceling signal and the second noise canceling signal.

[0441] The sound reproduction device described in (2) above.

[0442] (14)

[0443] The high-frequency component of the first collected signal is extracted by a high-pass filter, a high-shelving filter, or a high-peak EQ filter, and

[0444] The low-frequency component of the second sound collection signal is extracted by a low-pass filter, a low-shelving filter, or a low-peak EQ filter,

[0445] The sound reproduction device described in (13) above.

[0446] (15)

[0447] It is equipped with a third microphone used for noise cancellation processing by a feedforward method, and

[0448] The above acoustic signal processing unit generates the noise canceling signal using the first sound collection signal, the second sound collection signal, and the third sound collection signal collected by the third microphone.

[0449] A sound reproduction device described in any one of (1) to (14) above.

[0450] (16)

[0451] A sound signal processing unit having a first sound-collected signal collected by a first microphone used for noise cancellation processing by a feedback method, and a second sound-collected signal collected by a second microphone having a sound-collecting surface in a direction different from that of the first microphone and used for noise cancellation processing by a feedback method, which generates a noise canceling signal.

[0452] Signal processing device.

[0453] (17)

[0454] A noise canceling signal is generated using a first sound-collected signal collected by a first microphone used for noise canceling processing by a feedback method, and a second sound-collected signal collected by a second microphone used for noise canceling processing by a feedback method, the second microphone having a sound-collecting surface in a direction different from that of the first microphone.

[0455] Signal processing method. Explanation of the symbols

[0456] 1, 1A, 1B, 1C, 1D, 1E, 1F: Sound playback device 3: Housing 4: Driver Unit 7a: Forward space (First acoustic space) 8: Sound induction space (second acoustic space) 9: Soundproof 11: First microphone 11a: Sound-collecting surface 12: Second microphone 12a: Sound-collecting surface 23A: 1st DSP (Acoustic Signal Processing Unit) 23B: 2nd DSP (Acoustic Signal Processing Unit) 31: HPF 32: 1st FB Filter 33: LPF 34: 2nd FB Filter 51: Acoustic resistance member 52: Inner space (first acoustic space) 61: Third microphone 63: Third FF Filter 71: HPF 72: LPF S1: First sound collection signal S2: Second sound collection signal S3: Third sound collection signal Snc1: First noise canceling signal Snc2: Second noise canceling signal Snc: Synthetic noise canceling signal

Claims

Claim 1 A sound reproduction device comprising: a housing having a soundproof hole that isolates the output sound from the driver unit, wherein the driver unit is disposed to produce sound output based on a noise canceling signal; a sound resistance member that isolates a first acoustic space and a second acoustic space; a first microphone disposed in the first acoustic space and used for noise canceling processing by a feedback method; a second microphone disposed in the second acoustic space and having a sound collecting surface in a direction different from that of the first microphone and used for noise canceling processing by a feedback method; and a sound signal processing unit that generates the noise canceling signal using a first sound collecting signal collected by the first microphone and a second sound collecting signal collected by the second microphone, wherein the first acoustic space is a space enclosed by the driver unit, the sound resistance member, and the housing, and the second acoustic space is a space enclosed by the sound resistance member, the housing, and the soundproof hole. Claim 2 In claim 1, the sound collecting surface of the first microphone is located closer to the driver unit than the sound collecting surface of the second microphone. Claim 3 In claim 1, the sound collecting surface of the first microphone is a sound reproduction device positioned opposite the sound insulation direction of the driver unit. Claim 4 In claim 1, the second microphone is a sound reproduction device located closer to the soundproof hole than the first microphone. Claim 5 In claim 1, the sound collecting surface of the second microphone is positioned so as not to face the sound insulation direction of the driver unit. Claim 6 In paragraph 2, the sound reproduction device comprises a first feedback filter that generates a first noise canceling signal based on a high-frequency component of the first sound collection signal and a second feedback filter that generates a second noise canceling signal based on a low-frequency component of the second sound collection signal, and the sound signal processing unit generates the noise canceling signal based on the first noise canceling signal and the second noise canceling signal. Claim 7 An audio reproduction device according to claim 6, wherein the high-frequency component of the first collected signal is extracted by a high-pass filter, a high-shelving filter, or a high-peak EQ filter, and the low-frequency component of the second collected signal is extracted by a low-pass filter, a low-shelving filter, or a low-peak EQ filter. Claim 8 An audio playback device according to claim 1, comprising a third microphone used for noise cancellation processing by a feedforward method, wherein the acoustic signal processing unit generates the noise canceling signal using the first sound collection signal, the second sound collection signal, and the third sound collection signal collected by the third microphone. Claim 9 A signal processing device comprising an acoustic signal processing unit that generates the noise canceling signal using a first sound-collecting signal collected by a first microphone disposed in a first acoustic space enclosed by the driver unit, an acoustic resistance member, and the housing and used for noise canceling processing by a feedback method, and a second sound-collecting signal collected by a second microphone disposed in a second acoustic space enclosed by the acoustic resistance member, the housing, and the sound-collecting hole, having a sound-collecting surface in a direction different from that of the first microphone and used for noise canceling processing by a feedback method. Claim 10 A signal processing method for generating a noise canceling signal using a first sound-collecting signal collected by a first microphone disposed in a first acoustic space enclosed by the driver unit, an acoustic resistance member, and the housing, and used for noise canceling processing by a feedback method, and a second sound-collecting signal collected by a second microphone disposed in a second acoustic space enclosed by the acoustic resistance member, the housing, and the sound-collecting hole, having a sound-collecting surface in a direction different from that of the first microphone, and used for noise canceling processing by a feedback method. Claim 11 delete Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 delete

Images