Sound processing device and in-vehicle audio system

Abstract

To be able to reduce disturbance sound audible in a first zone while maintaining a disturbance effect.SOLUTION: A sound processing device 30 comprises a first filter group FG1 and a second filter group FG2. The first filter group FG1 controls first disturbance sound output from a first speaker set 41 located in a first zone ZN1. The second filter group FG2 controls second disturbance sound output from a second speaker set 42 located in a second zone ZN2 that is adjacent to the first zone ZN1. Characteristics of the first filter group FG1 and characteristics of the second filter group FG2 are set so that the sum of volume of the first disturbance sound and volume of the second disturbance sound heard in the second zone ZN2 is greater than the sum of the volume of the first disturbance sound and the volume of the second disturbance sound heard in the first zone ZN1.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a sound processing device and an in-vehicle audio system. [Background technology]

[0002] Conventionally, a technique for masking a call has been known in order to protect the privacy of a driver in a hands-free call by a driver of a vehicle, etc. For example, Patent Document 1 discloses a voice reproducing device in which a received voice signal is reproduced in a clear voice zone and a masking sound that masks the voice is reproduced in a voice masking zone. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2018-506080 Summary of the Invention [Problem to be solved by the invention]

[0004] In the audio reproducing device described in Patent Document 1, an analysis signal is generated based on the spectrum and / or temporal characteristics of a received telephone call audio signal. In the audio reproducing device, a signal indicating a masking sound is generated based on the generated analysis signal. The generated signal is output to a speaker arranged in a sound masking zone. The speaker outputs the masking sound. However, since the masking sound has a low effect of masking low-frequency sounds, it is necessary to increase the masking sound, especially in the low-frequency range. As a result, the conventional audio reproducing device has a problem of giving a sense of discomfort to the driver and passengers.

[0005] In consideration of the above circumstances, an object of one aspect of the present disclosure is to provide a sound processing device that can reduce an interfering sound heard in the first zone while maintaining the interfering effect. [Means for solving the problem]

[0006] In order to solve the above problems, a sound processing device according to one embodiment of the present disclosure comprises a first filter group including one or more filters that receive a first sound signal and control a first interfering sound output from a first speaker set including one or more speakers arranged in a first zone, and a second filter group including one or more filters that receive the first sound signal and control a second interfering sound output from a second speaker set including one or more speakers arranged in a second zone adjacent to the first zone, wherein the characteristics of the first filter group and the characteristics of the second filter group are set so that the sum of the volume of the first interfering sound and the volume of the second interfering sound heard in the second zone is greater than the sum of the volume of the first interfering sound and the volume of the second interfering sound heard in the first zone.

[0007] An in-vehicle audio system according to one embodiment of the present disclosure comprises a first speaker set arranged in a first zone, a second speaker set arranged in a second zone adjacent to the first zone, and a sound processing device having a first filter group that controls a first interference sound output from the first speaker set, a second filter group that controls a second interference sound output from the second speaker set, a third filter group that controls a first reproduced sound output from the first speaker set, and a fourth filter group that controls a second reproduced sound output from the second speaker set, wherein the characteristics of the first filter group and the characteristics of the second filter group are set so that the sum of the volume of the first interference sound and the volume of the second interference sound heard in the second zone is greater than the sum of the volume of the first interference sound and the volume of the second interference sound heard in the first zone, and the characteristics of the third filter group and the characteristics of the fourth filter group are set so that the sum of the volume of the first reproduced sound and the volume of the second reproduced sound heard in the first zone is greater than the sum of the volume of the first reproduced sound and the volume of the second reproduced sound heard in the second zone. [Brief description of the drawings]

[0008]

Figure 1

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[0009] A: First embodiment A1: Configuration of sound processing device Fig. 1 is a block diagram showing an example of an in-vehicle audio system 1 including a sound processing device 30 according to a first embodiment. Fig. 2 is a configuration diagram showing an example of the in-vehicle audio system 1 of Fig. 1. Fig. 3 is a front view showing an example of an arrangement of a first speaker set 41 and a second speaker set 42. Fig. 4 is a plan view showing an example of an arrangement of the first speaker set 41 and the second speaker set 42.

[0010] The in-vehicle audio system 1 is mounted on, for example, a vehicle such as an automobile. As shown in Fig. 1 and Fig. 2, the in-vehicle audio system 1 includes a storage device 10, a sound generating device 20, a sound processing device 30, and a speaker device 40.

[0011] The storage device 10 is a recording medium readable by a computer (e.g., a non-transitive recording medium readable by a computer). The storage device 10 includes a non-volatile memory and a volatile memory. The non-volatile memory is, for example, a Read Only Memory (ROM), an Erasable Programmable Read Only Memory (EPROM), and an Electrically Erasable Programmable Read Only Memory (EEPROM). The volatile memory is, for example, a Random Access Memory (RAM).

[0012] The storage device 10 stores a program pr1 and various information. The program pr1 defines the operations of the sound generating device 20 and the sound processing device 30. The storage device 10 may store the program pr1 read from a storage device in a server (not shown). In this case, the storage device in the server is an example of a computer-readable recording medium.

[0013] The sound generating device 20 and the sound processing device 30 read the program pr1 from the storage device 10. The sound generating device 20 executes the program pr1 to function as a jamming signal generating unit 21 and a call signal generating unit 22. The sound processing device 30 executes the program pr1 to function as a jamming sound filter unit 31, a call sound filter unit 32, and a mixer 33. At least one of the jamming signal generating unit 21, the call signal generating unit 22, the jamming sound filter unit 31, the call sound filter unit 32, and the mixer 33 may be realized by a circuit such as a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0014] The interference signal generating unit 21 generates a first original signal SO1. The first original signal SO1 is a signal that is the basis of an interference sound that is output to the second zone so that the voice of the person making a call in the first zone ZN1 and the voice of the other party in the call are difficult to hear for people in the second zone ZN2 adjacent to the first zone ZN1. In this embodiment, the person making a call in the first zone ZN1 is the driver of the vehicle 100, and the person in the second zone is a passenger in the vehicle 100.

[0015] The speech signal generating unit 22 generates a second original signal SO2. The second original signal SO2 is a signal related to the voice of the driver who is speaking with the other party in the first zone ZN1.

[0016] The interference sound filter section 31 has a first low-pass filter LP1, a first filter group FG1, a second filter group FG2, a first high-pass filter HP1, a first delay unit DL1, a first amplifier group AG1, a second amplifier group AG2, a first mixer MX1, a second mixer MX2, a third mixer MX3, and a fourth mixer MX4. The first filter group FG1 and the second filter group FG2 are zoning filters.

[0017] Zoning filters are used to control the acoustic characteristics of an acoustic space divided into multiple zones by applying different acoustic processing to each zone. Since adjusting the acoustic characteristics becomes more difficult as the frequency increases, it is generally said that a frequency band below 500 Hz is effective for zoning filters. For this reason, by filtering only low-frequency signals that are effective for controlling acoustic characteristics and mixing high-frequency signals with the filtered signal, it is possible to reduce the computational load on the filter without compromising the effectiveness of the filter.

[0018] The first low-pass filter LP1 outputs a first low-frequency signal SL1 by cutting off high-frequency components of the first original signal SO1. The first low-frequency signal SL1 is an example of a "first sound signal." The cutoff frequency of the first low-pass filter LP1 is, for example, 500 Hz.

[0019] The first low-frequency signal SL1 is input to the first filter group FG1 and the second filter group FG2. Since the first low-frequency signal SL1 is a signal from which high-frequency components equal to or higher than the cutoff frequency have been removed by the first low-pass filter LP1, it is possible to reduce the computation load in the subsequent first filter group FG1 and second filter group FG2.

[0020] The first filter group FG1 includes a first filter FL1 and a second filter FL2. As described later, the phase characteristics and amplitude characteristics of the first filter FL1 and the second filter FL2 are calculated in the frequency domain. In order to accurately express the phase characteristics and amplitude characteristics of the filters calculated in the frequency domain, a FIR (Finite Impulse Response) filter is suitable. Therefore, in this embodiment, an FIR filter is adopted for each of the first filter FL1 and the second filter FL2.

[0021] The second filter group FG2 includes a third filter FL3 and a fourth filter FL4. As with the first filter FL1 and the second filter FL2, the third filter FL3 and the fourth filter FL4 each employ an FIR filter.

[0022] The first high-pass filter HP1 outputs the first high-frequency signal SH1 by cutting off the low-frequency components of the first original signal SO1. The cutoff frequency of the first high-pass filter HP1 is equal to the cutoff frequency of the first low-pass filter LP1. The first delay device DL1 delays the phase of the first high-frequency signal SH1. The amount of delay by the first delay device DL1 is determined taking into consideration the respective amounts of delay in the first filter group FG1 and the second filter group FG2.

[0023] The first amplifier group AG1 includes a first amplifier AM1 and a second amplifier AM2. The first amplifier group AG1 is a variable gain amplifier. That is, the first amplifier AM1 and the second amplifier AM2 are each a variable gain amplifier. A signal obtained by adjusting the amplitude of the first high frequency signal SH1 by the first amplifier AM1 and a signal output from the first filter FL1 are mixed by a first mixer MX1. A signal obtained by adjusting the amplitude of the first high frequency signal SH1 by the second amplifier AM2 and a signal output from the second filter FL2 are mixed by a second mixer MX2.

[0024] The second amplifier group AG2 includes a third amplifier AM3 and a fourth amplifier AM4. The second amplifier group AG2 is a variable gain amplifier. That is, the third amplifier AM3 and the fourth amplifier AM4 are each a variable gain amplifier. The signal obtained by adjusting the amplitude of the first high frequency signal SH1 by the third amplifier AM3 and the signal output from the third filter FL3 are mixed by the third mixer MX3. The signal obtained by adjusting the amplitude of the first high frequency signal SH1 by the fourth amplifier AM4 and the signal output from the fourth filter FL4 are mixed by the fourth mixer MX4.

[0025] The first filter FL1 corresponds to the first speaker SP1 of the first speaker set 41. The second filter FL2 corresponds to the second speaker SP2 of the first speaker set 41. The third filter FL3 corresponds to the third speaker SP3 of the second speaker set 42. The fourth filter FL4 corresponds to the fourth speaker SP4 of the second speaker set 42.

[0026] The speech sound filter unit 32 has a second low-pass filter LP2, a third filter group FG3, a fourth filter group FG4, a second high-pass filter HP2, a second delay unit DL2, a third amplifier group AG3, a fourth amplifier group AG4, a fifth mixer MX5, a sixth mixer MX6, a seventh mixer MX7, and an eighth mixer MX8. The third filter group FG3 and the fourth filter group FG4 are zoning filters.

[0027] The second low-pass filter LP2 outputs a second low-frequency signal SL2 by cutting off the high-frequency components of the second original signal SO2. The second low-frequency signal SL2 is an example of a "second sound signal." The cutoff frequency of the second low-pass filter LP2 is equal to the cutoff frequency of the first low-pass filter LP1.

[0028] The second low-frequency signal SL2 is input to the third filter group FG3 and the fourth filter group FG4. Since the second low-frequency signal SL2 is a signal from which high-frequency components equal to or higher than the cutoff frequency have been removed by the second low-pass filter LP2, the computation load in the subsequent third filter group FG3 and fourth filter group FG4 can be reduced.

[0029] The third filter group FG3 includes a fifth filter FL5 and a sixth filter FL6. Like the first filter FL1 to the fourth filter FL4, the fifth filter FL5 and the sixth filter FL6 each employ an FIR filter.

[0030] The fourth filter group FG4 includes a seventh filter FL7 and an eighth filter FL8. As with the first filter FL1 to the sixth filter FL6, the seventh filter FL7 and the eighth filter FL8 each employ an FIR filter.

[0031] The second high-pass filter HP2 outputs a second high-frequency signal SH2 by cutting off the low-frequency components of the second original signal SO2. The cutoff frequency of the second high-pass filter HP2 is equal to the cutoff frequency of the second low-pass filter LP2. The second delay device DL2 delays the phase of the second high-frequency signal SH2. The amount of delay by the second delay device DL2 is determined taking into consideration the respective delay amounts in the third filter group FG3 and the fourth filter group FG4.

[0032] The third amplifier group AG3 includes a fifth amplifier AM5 and a sixth amplifier AM6. The third amplifier group AG3 is a variable gain amplifier. That is, the fifth amplifier AM5 and the sixth amplifier AM6 are each a variable gain amplifier. The signal obtained by adjusting the amplitude of the second high frequency signal SH2 by the fifth amplifier AM5 and the signal output from the fifth filter FL5 are mixed by the fifth mixer MX5. The signal obtained by adjusting the amplitude of the second high frequency signal SH2 by the sixth amplifier AM6 and the signal output from the sixth filter FL6 are mixed by the sixth mixer MX6.

[0033] The fourth amplifier group AG4 includes a seventh amplifier AM7 and an eighth amplifier AM8. The fourth amplifier group AG4 is a variable gain amplifier. That is, the seventh amplifier AM7 and the eighth amplifier AM8 are each a variable gain amplifier. The signal in which the amplitude of the second high frequency signal SH2 is adjusted by the seventh amplifier AM7 and the signal output from the seventh filter FL7 are mixed by the seventh mixer MX7. The signal in which the amplitude of the second high frequency signal SH2 is adjusted by the eighth amplifier AM8 and the signal output from the eighth filter FL8 are mixed by the eighth mixer MX8.

[0034] The fifth filter FL5 corresponds to the first speaker SP1 of the first speaker set 41. The sixth filter FL6 corresponds to the second speaker SP2 of the first speaker set 41. The seventh filter FL7 corresponds to the third speaker SP3 of the second speaker set 42. The eighth filter FL8 corresponds to the fourth speaker SP4 of the second speaker set 42.

[0035] The mixer 33 includes an eleventh mixer MX11, a twelfth mixer MX12, a thirteenth mixer MX13, and a fourteenth mixer MX14. The eleventh mixer MX11 mixes the signal output from the first mixer MX1 ​​and the signal output from the fifth mixer MX5, and outputs the mixed signal to the first speaker SP1. The twelfth mixer MX12 mixes the signal output from the second mixer MX2 and the signal output from the sixth mixer MX6, and outputs the mixed signal to the second speaker SP2. The thirteenth mixer MX13 mixes the signal output from the third mixer MX3 and the signal output from the seventh mixer MX7, and outputs the mixed signal to the third speaker SP3. The fourteenth mixer MX14 mixes the signal output from the fourth mixer MX4 and the signal output from the eighth mixer MX8, and outputs the mixed signal to the fourth speaker SP4.

[0036] The speaker device 40 has a first speaker set 41 and a second speaker set 42. As shown in Figs. 3 and 4, a first seat 90R and a second seat 90L are arranged side by side in the vehicle 100. The first seat 90R is arranged on the right side of the center of the vehicle 100. The first seat 90R has a headrest 91R, a seat back 92R, and a cushion 93R. The second seat 90L is arranged on the left side of the center of the vehicle 100. The second seat 90L has a headrest 91L, a seat back 92L, and a cushion 93L.

[0037] The first speaker set 41 is provided in the headrest 91R of the first seat 90R. The first speaker SP1 is provided on the left side of the headrest 91R. The second speaker SP2 is provided on the right side of the headrest 91R. The second speaker set 42 is provided in the headrest 91L of the second seat 90L. The third speaker SP3 is provided on the left side of the headrest 91L. The fourth speaker SP4 is provided on the right side of the headrest 91L.

[0038] The first interference sound is the interference sound output from the first speaker set 41. The second interference sound is the interference sound output from the second speaker set 42. The first call sound is the call sound output from the first speaker set 41. The second call sound is the call sound output from the second speaker set 42. In other words, the first speaker set 41 outputs the first interference sound and the first call sound. The second speaker set 42 outputs the second interference sound and the second call sound.

[0039] The first call sound is an example of a "first playback sound," and the second call sound is an example of a "second playback sound." In addition to the call sound, the playback sound includes music playback sound, video content playback sound, announcement sound, various notification sounds, etc. In this embodiment, the call sound will be described as an example.

[0040] The first zone ZN1 includes the first speaker set 41 and is an area that includes the head of a passenger when the passenger sits in the first seat 90R. In other words, the first speaker set 41 is disposed in the first zone ZN1. The second zone ZN2 includes the second speaker set 42 and is an area that includes the head of a passenger when the passenger sits in the second seat 90L. In other words, the second speaker set 42 is disposed in the second zone ZN2.

[0041] Next, a design procedure for the first filter FL1 to the eighth filter FL8 will be described with reference to FIG.

[0042] FIG. 5 is an explanatory diagram of the speakers and virtual microphones arranged in the first zone ZN1 and the second zone ZN2. As shown in FIG. 5, the first zone ZN1 includes a first speaker set 41 and ten virtual microphones M1 to M10. The virtual microphones M1 to M5 are arranged in the vicinity of the first speaker SP1. The power output by the virtual microphones M1, M2, M3, M4, and M5 is respectively defined as p 1 , p 2 , p 3 , p 4 , and p 5Let it be so. The virtual microphones M6 to M10 are arranged near the second speaker SP2. Let the power output from the virtual microphones M6, M7, M8, M9, and M10 be p 6 , p 7 , p 8 , p 9 , and p 10 respectively.

[0043] In the second zone ZN2, a second speaker set 42 is arranged, and ten virtual microphones M11 to M20 are arranged. The virtual microphones M11 to M15 are arranged near the third speaker SP3. Let the power output from the virtual microphones M11, M12, M13, M14, and M15 be p 11 , p 12 , p 13 , p 14 , and p 15 respectively. The virtual microphones M16 to M20 are arranged near the fourth speaker SP4. Let the power output from the virtual microphones M16, M17, M18, M19, and M20 be p 16 , p 17 , p 18 , p 19 , and p 20 respectively.

[0044] A first original signal SO1 is input to the first speaker SP1 via a first filter control circuit FC1. The first filter control circuit FC1 is a circuit including a first low-pass filter LP1, a first filter FL1, a first high-pass filter HP1, a first delay device DL1, a first amplifier AM1, a first mixer MX1, and an eleventh mixer MX11.

[0045] A first original signal SO1 is input to the second speaker SP2 via a second filter control circuit FC2. The second filter control circuit FC2 is a circuit including a first low-pass filter LP1, a second filter FL2, a first high-pass filter HP1, a first delay device DL1, a second amplifier AM2, a second mixer MX2, and a twelfth mixer MX12.

[0046] The first original signal SO1 is input to the third speaker SP3 via a third filter control circuit FC3. The third filter control circuit FC3 is a circuit including a first low-pass filter LP1, a third filter FL3, a first high-pass filter HP1, a first delay unit DL1, a third amplifier AM3, a third mixer MX3, and a thirteenth mixer MX13.

[0047] The first original signal SO1 is input to the fourth speaker SP4 via a fourth filter control circuit FC4. The fourth filter control circuit FC4 is a circuit including a first low-pass filter LP1, a fourth filter FL4, a first high-pass filter HP1, a first delay unit DL1, a fourth amplifier AM4, a fourth mixer MX4, and a fourteenth mixer MX14.

[0048] Thus, in the example shown in Figure 5, the first speaker set 41 and the second speaker set 42 have a total of four speakers, and it is assumed that 20 virtual microphones M1 to M20 are virtually placed in the entire zone including the first zone ZN1 and the second zone ZN2.

[0049] Hereinafter, the zoning filter for interference sounds will be considered with reference to the examples shown in Figs. 3 to 5. For example, in a right-hand drive vehicle, the first seat 90R corresponds to the driver's seat, and the second seat 90L corresponds to the passenger's seat. In this case, the person sitting in the first seat 90R is the driver, and the person sitting in the second seat 90L is the passenger. As a premise of this embodiment, when the driver makes or receives a phone call, a hands-free call is performed. In this case, interference sounds are output so that the passengers have difficulty hearing the call sounds.

[0050] The low-frequency interference sound based on the first low-frequency signal SL1 is output from any one of the first speaker SP1, the second speaker SP2, the third speaker SP3, and the fourth speaker SP4.

[0051] The characteristic functions showing the characteristics of the first filter group FG1 and the second filter group FG2 are g jammer Here, the characteristic function g for the interference sound is jammerSince the number of speakers is four, it is expressed by a 4-row, 1-column matrix as shown in the following equation (1). g jammer =[g 1 g 2 g 3 g 4 ] T (1)

[0052] The target characteristics of the zoning filter for interference sounds must be such that at least the sum of the volume of the first interference sound and the volume of the second interference sound heard in the second zone ZN2 is greater than the sum of the volume of the first interference sound and the volume of the second interference sound heard in the first zone ZN1.

[0053] As the target characteristic of the zoning filter for interference noise, the target function d that satisfies the following conditions is obtained from the results of experiments, simulations, etc. jammer The inventor has proposed the objective function d for the interference sound. jammer Since the number of virtual microphones is 20, it is expressed by a matrix with 20 rows and 1 column as shown in the following equation (2). d jammer =[p 1 p 2 … p 20 ] T (2)

[0054] Objective function d for disturbing sounds jammer The conditions that must be satisfied are the following conditions (a) and (b). (a) No sound is heard from the virtual microphones M1 to M10, that is, the power p 1 ~p 10 becomes 0. (b) Interference sounds are output in opposite phases from the third speaker SP3 and the fourth speaker SP4 provided in the headrest 91L of the passenger seat, and power p is output from the virtual microphones M11 to M20. 11 ~p 20 will be output.

[0055] The transfer function indicating the transfer characteristics from the inputs of the first filter group FG1 and the second filter group FG2 to the outputs of the M virtual microphones M1 to M20 is expressed by a 20-row, 4-column transfer function matrix H 20×4 It is expressed by:

[0056] The characteristics of the first filter group FG1 and the second filter group FG2 are expressed by a characteristic function g jammer This can be obtained by calculating an approximation of H 20×4 *g jammer =d jammer (3)

[0057] More specifically, the transfer function matrix H is a 20-row, 4-column matrix that is irregular, so the inverse matrix cannot be found. jammer As an approximate solution, the least squares solution of the following equation (4) is obtained. g jammer =(H H H 20×4 +λI) -1 H H d jammer (4) Here, H H is the transfer function matrix H 20×4 , λ is the adjoint matrix H H where I is the identity matrix.

[0058] At this time, the high-frequency interference sound based on the first high-frequency signal SH1 is controlled to be output from the third speaker SP3 and the fourth speaker SP4 and not output from the first speaker SP1 and the second speaker SP2. More specifically, the gain of the first amplifier AM1 and the gain of the second amplifier AM2 are both set to 0.

[0059] In this way, the characteristics of the first filter group FG1 and the second filter group FG2 are expressed by the characteristic function g jammer The characteristic function g jammerIt is set such that the sum of the volume of the first interfering sound and the volume of the second interfering sound audible in the second zone ZN2 is greater than the sum of the volume of the first interfering sound and the volume of the second interfering sound audible in the first zone ZN1.

[0060] Next, with reference to the example shown in FIG. 5, the zoning filter for the call sound will be considered. The call sound is output from each speaker. In this case, the first filter control circuit FC1, the second filter control circuit FC2, the third filter control circuit FC3, and the fourth filter control circuit FC4 in FIG. 5 are respectively read as the fifth filter control circuit FC5, the sixth filter control circuit FC6, the seventh filter control circuit FC7, and the eighth filter control circuit FC8.

[0061] The fifth filter control circuit FC5 is a circuit including a second low-pass filter LP2, a fifth filter FL5, a second high-pass filter HP2, a second delay device DL2, a fifth amplifier AM5, a fifth mixer MX5, and an eleventh mixer MX11.

[0062] The sixth filter control circuit FC6 is a circuit including a second low-pass filter LP2, a sixth filter FL6, a second high-pass filter HP2, a second delay device DL2, a sixth amplifier AM6, a sixth mixer MX6, and a twelfth mixer MX12.

[0063] The seventh filter control circuit FC7 is a circuit including a second low-pass filter LP2, a seventh filter FL7, a second high-pass filter HP2, a second delay device DL2, a seventh amplifier AM7, a seventh mixer MX7, and a thirteenth mixer MX13.

[0064] The eighth filter control circuit FC8 is a circuit including a second low-pass filter LP2, an eighth filter FL8, a second high-pass filter HP2, a second delay device DL2, an eighth amplifier AM8, an eighth mixer MX8, and a fourteenth mixer MX14.

[0065] A low-frequency call sound based on the second low-frequency signal SL2 is output from any one of the first speaker SP1, the second speaker SP2, the third speaker SP3, and the fourth speaker SP4.

[0066] A characteristic function indicating the characteristics of each filter in the first filter group FG1 and the characteristics of each filter in the second filter group FG2 is denoted by g. Here, the characteristic function g for speech sound is expressed by a 4-row, 1-column matrix as shown in the following formula (5) since the number of speakers is four. g voice =[g 1 g 2 g 3 g 4 ] T (5)

[0067] The target characteristic of the zoning filter for call sounds must be such that at least the sum of the volume of the first call sound and the volume of the second call sound heard in the first zone ZN1 is greater than the sum of the volume of the first call sound and the volume of the second call sound heard in the second zone ZN2.

[0068] As the target characteristic of the zoning filter for speech, the target function d that satisfies the following conditions is obtained from the results of experiments, simulations, etc. voice The inventors have proposed a target function d for speech sound. voice Since the number of virtual microphones is 20, it is expressed by a matrix with 20 rows and 1 column as shown in the following equation (6). d voice =[p 1 p 2 … p 20 ] T (6)

[0069] Objective function for speech sound d voice The conditions that must be satisfied are the following conditions (c) and (d). (c) When there is no sound in the virtual microphones M1 to M5 and M11 to M20, that is, when the power p 1 ~p 5 and p 11 ~p 20 becomes 0. (d) A call sound is output from the second speaker SP2 provided in the headrest 91R of the driver's seat, and power p is output from the virtual microphones M6 to M10. 6 ~p 10 will be output.

[0070] The transfer function indicating the transfer characteristics from the inputs of the third filter group FG3 and the fourth filter group FG4 to the outputs of the M virtual microphones M1 to M20 is expressed by a 20-row, 4-column transfer function matrix H 20×4 It is expressed by:

[0071] The characteristics of the third filter group FG3 and the fourth filter group FG4 are expressed by a characteristic function g voice This can be obtained by calculating an approximation of H 20×4 *g voice =d voice (7)

[0072] Characteristic function g voice As an approximate solution, the least squares solution of the following equation (8) is obtained. g voice =(H H H 20×4 +λI) -1 H H d voice (8)

[0073] At this time, the high-frequency call sound based on the second high-frequency signal SH2 is controlled to be output from the first speaker SP1, the second speaker SP2, the third speaker SP3, and the fourth speaker SP4.

[0074] In this way, the characteristics of the third filter group FG3 and the fourth filter group FG4 are expressed by the characteristic function gvoice The characteristic function g voice is set so that the sum of the volume of the first call sound and the volume of the second call sound heard in the first zone ZN1 is greater than the sum of the volume of the first call sound and the volume of the second call sound heard in the second zone ZN2.

[0075] A2: Summary of the first embodiment As described above, the sound processing device 30 according to the first embodiment includes a first filter group FG1 and a second filter group FG2. A first low-frequency signal SL1 is input to the first filter group FG1. The first filter group FG1 includes a first filter FL1 and a second filter FL2. The first filter FL1 and the second filter FL2 control a first interference sound output from a first speaker set 41 arranged in a first zone ZN1. The first speaker set 41 includes a first speaker SP1 and a second speaker SP2.

[0076] The first low-frequency signal SL1 is input to the second filter group FG2. The second filter group FG2 includes a third filter FL3 and a fourth filter FL4. The third filter FL3 and the fourth filter FL4 control a second interference sound output from a second speaker set 42 arranged in a second zone ZN2 adjacent to the first zone ZN1. The second speaker set 42 includes a third speaker SP3 and a fourth speaker SP4.

[0077] The characteristics of the first filter group FG1 and the characteristics of the second filter group FG2 are set so that the sum of the volume of the first interfering sound and the volume of the second interfering sound heard in the second zone ZN2 is greater than the sum of the volume of the first interfering sound and the volume of the second interfering sound heard in the first zone ZN1.

[0078] According to this embodiment, the first filter group FG1 and the second filter group FG2 can reduce the disturbance sound heard in the first zone ZN1. Therefore, the driver's discomfort can be suppressed. In addition, since the disturbance sound is difficult to hear in the first zone ZN1, the driver can lower the volume of the call sound.

[0079] The sound processing device 30 according to the first embodiment further includes a third filter group FG3 and a fourth filter group FG4. A second low-frequency signal SL2 is input to the third filter group FG3. The third filter group FG3 includes a fifth filter FL5 and a sixth filter FL6. The fifth filter FL5 and the sixth filter FL6 control the first call sound output from the first speaker set 41.

[0080] The second low-frequency signal SL2 is input to the fourth filter group FG4. The fourth filter group FG4 includes a seventh filter FL7 and an eighth filter FL8. The seventh filter FL7 and the eighth filter FL8 control the second call sound output from the second speaker set 42.

[0081] The characteristics of the third filter group FG3 and the characteristics of the fourth filter group FG4 are set so that the sum of the volume of the first call sound and the volume of the second call sound heard in the first zone ZN1 is greater than the sum of the volume of the first call sound and the volume of the second call sound heard in the second zone ZN2.

[0082] According to this embodiment, the third filter group FG3 and the fourth filter group FG4 can reduce the volume of the call sound heard in the second zone ZN2. Therefore, the discomfort of the passenger can be suppressed. In addition, since the call sound is difficult to hear in the second zone ZN2, the volume of the jamming sound can be reduced. In particular, in a frequency band below 500 Hz, it is necessary to increase the volume of the jamming sound to obtain the effect of the jamming sound. However, according to this embodiment, zoning is also performed on the call sound, so that the effect of the jamming sound in a frequency band below 500 Hz is complemented.

[0083] Also, in the sound processing apparatus 30 according to the first embodiment, assume that the first speaker set 41 and the second speaker set 42 have a total of four speakers, and a total of 20 virtual microphones M1 to M20 are virtually arranged in the entire zone including the first zone ZN1 and the second zone ZN2. The characteristics of the first filter group FG1 and the characteristics of the second filter group FG2 are the transfer function matrix H 20×4 and the characteristic function g jammer and the objective function d jammer satisfy the relationship H 20×4 *g jammer =d jammer and are obtained by calculating an approximate solution of the characteristic function g jammer .

[0084] The transfer function matrix H 20×4 is represented by a 20-row 4-column matrix and shows the transfer characteristics from the inputs of the first filter group FG1 and the second filter group FG2 to the outputs of the 20 virtual microphones M1 to M20. The characteristic function g jammer is represented by a 4-row 1-column matrix, and each component of the 4-row 1-column matrix represents the characteristics of the first filter FL1 and the second filter FL2 in the first filter group FG1 and the characteristics of the third filter FL3 and the fourth filter FL4 in the second filter group FG2, respectively. The objective function d jammer is represented by a 20-row 1-column matrix, and each component of the 20-row 1-column matrix represents the target value of the power corresponding to the first interfering sound output from each of the 20 virtual microphones M1 to M20 and the target value of the power corresponding to the second interfering sound output from each of the 20 virtual microphones M1 to M20, respectively.

[0085] According to this aspect, the first filter group FG1 and the second filter group FG2 that reduce the interfering sound audible in the first zone ZN1 can be designed more easily.

[0086] In the sound processing device 30 according to the first embodiment, it is assumed that the first speaker set 41 and the second speaker set 42 each have a total of four speakers, and 20 virtual microphones M1 to M20 are virtually arranged in the entire zone including the first zone ZN1 and the second zone ZN2. The characteristics of the third filter group FG3 and the characteristics of the fourth filter group FG4 are expressed by a transfer function matrix H 20×4 and the characteristic function g voice and the objective function d voice But, H 20×4 *g voice =d voice The characteristic function g that satisfies the relationship voice This can be obtained by calculating an approximation of

[0087] Transfer function matrix H 20×4 is expressed by a matrix of 20 rows and 4 columns, and indicates the transfer characteristics from the inputs of the third filter group FG3 and the fourth filter group FG4 to the outputs of the 20 virtual microphones M1 to M20. jammer is expressed by a 4-row, 1-column matrix, and each element of the 4-row, 1-column matrix indicates the characteristics of the fifth filter FL5 and the sixth filter FL6 in the third filter group FG3 and the characteristics of the seventh filter FL7 and the eighth filter FL8 in the fourth filter group FG4, respectively. jammer is represented by a 20-row, 1-column matrix, and each element of the 20-row, 1-column matrix indicates a target value of power corresponding to a first call sound output from each of the 20 virtual microphones M1 to M20 and a target value of power corresponding to a second call sound output from each of the 20 virtual microphones M1 to M20.

[0088] According to this embodiment, it is possible to more easily design the third filter group FG3 and the fourth filter group FG4 so as to reduce the volume of the call sound heard in the second zone ZN2.

[0089] In the sound processing device 30 according to the first embodiment, a first low-pass filter LP1 is provided in front of the first filter group FG1 and the second filter group FG2. The first low-pass filter LP1 outputs a first low-frequency signal SL1 by blocking high-frequency components of a first original signal SO1, which is an original signal of the first interference sound and the second interference sound.

[0090] Since the zoning filter is effective in a relatively low frequency range, there is no problem in limiting the frequency range processed by the zoning filter to a relatively low frequency range. By limiting the frequency range processed by the zoning filter to a range below a predetermined frequency, the amount of calculation of the zoning filter can be reduced. Therefore, according to this embodiment, it is possible to perform calculations with higher accuracy without significantly increasing the processing load of the processor.

[0091] In the sound processing device 30 according to the first embodiment, a second low-pass filter LP2 is provided in front of the third filter group FG3 and the fourth filter group FG4. The second low-pass filter LP2 outputs a second low-frequency signal SL2 by cutting off high-frequency components of a second original signal SO2, which is an original signal of the first and second call sounds.

[0092] Since the zoning filter is effective in a relatively low frequency range, there is no problem in limiting the frequency range processed by the zoning filter to a relatively low frequency range. By limiting the frequency range processed by the zoning filter to a range below a predetermined frequency, the amount of calculation of the zoning filter can be reduced. Therefore, according to this embodiment, it is possible to perform calculations with higher accuracy without significantly increasing the processing load of the processor.

[0093] In the sound processing device 30 according to the first embodiment, a first low-pass filter LP1 is provided in front of the first filter group FG1 and the second filter group FG2. The first low-pass filter LP1 outputs a first low-frequency signal SL1 by blocking high-frequency components of a first original signal SO1, which is an original signal of the first interference sound and the second interference sound.

[0094] The first original signal SO1 is separated into a first low-frequency signal SL1 and a first high-frequency signal SH1 by a first low-pass filter LP1 and a first high-pass filter HP1 arranged in parallel with the first low-pass filter LP1. The first low-frequency signal SL1 that has passed through the first filter group FG1 is combined with a signal in which the amplitude of the first high-frequency signal SH1 has been adjusted by a first amplifier group AG1 arranged after the first high-pass filter HP1, and then input to the first speaker set 41. The first low-frequency signal SL1 that has passed through the second filter group FG2 is combined with a signal in which the amplitude of the first high-frequency signal SH1 has been adjusted by a second amplifier group AG2 arranged after the first high-pass filter HP1, and then input to the second speaker set 42.

[0095] The second original signal SO2 is separated into a second low-frequency signal SL2 and a second high-frequency signal SH2 by a second low-pass filter LP2 and a second high-pass filter HP2 arranged in parallel with the second low-pass filter LP2. The second low-frequency signal SL2 that has passed through the third filter group FG3 is combined with a signal obtained by adjusting the amplitude of the second high-frequency signal SH2 by a third amplifier group AG3 arranged after the second high-pass filter HP2, and then input to the first speaker set 41. The second low-frequency signal SL2 that has passed through the fourth filter group FG4 is combined with a signal obtained by adjusting the amplitude of the second high-frequency signal SH2 by a fourth amplifier group AG4 arranged after the second high-pass filter HP2, and then input to the second speaker set 42.

[0096] The cutoff frequency of the first low-pass filter LP1, the cutoff frequency of the first high-pass filter HP1, the cutoff frequency of the second low-pass filter LP2, and the cutoff frequency of the second high-pass filter HP2 are substantially equal to each other.

[0097] According to this aspect, the frequency bands processed by the first filter group FG1, the second filter group FG2, the third filter group FG3, and the fourth filter group FG4 are the same, making it easier to design the first filter group FG1, the second filter group FG2, the third filter group FG3, and the fourth filter group FG4.

[0098] In the sound processing device 30 according to the first embodiment, the first filter group FG1 and the second filter group FG2 are configured by FIR filters.

[0099] According to this embodiment, it is possible to precisely control the amplitude and phase of the first interfering sound generated from the first speaker set 41 and the amplitude and phase of the second interfering sound generated from the second speaker set 42. As a result, it is possible to reduce the volume of the interfering sound, and to suppress the discomfort felt by the driver and passengers.

[0100] In the sound processing device 30 according to the first embodiment, the third filter group FG3 and the fourth filter group FG4 are configured by FIR filters.

[0101] According to this embodiment, it is possible to precisely control the amplitude and phase of the first call sound generated from the first speaker set 41 and the amplitude and phase of the second call sound generated from the second speaker set 42. As a result, it is possible to reduce the volume of the interfering sound, and to suppress the discomfort felt by the driver and passengers.

[0102] The in-vehicle audio system 1 according to the first embodiment includes a first speaker set 41, a second speaker set 42, and a sound processing device 30. The first speaker set 41 is arranged in a first zone ZN1. The second speaker set 42 is arranged in a second zone ZN2 adjacent to the first zone ZN1.

[0103] The sound processing device 30 has a second filter group FG2, a third filter group FG3, and a fourth filter group FG4. The first filter group FG1 controls a first interference sound output from the first speaker set 41. The second filter group FG2 controls a second interference sound output from the second speaker set 42. The third filter group FG3 controls a first call sound output from the first speaker set 41. The fourth filter group FG4 controls a second call sound output from the second speaker set 42.

[0104] The characteristics of the first filter group FG1 and the characteristics of the second filter group FG2 are set so that the sum of the volume of the first and second interfering sounds heard in the second zone ZN2 is greater than the sum of the volume of the first and second interfering sounds heard in the first zone ZN1. The characteristics of the third filter group FG3 and the characteristics of the fourth filter group FG4 are set so that the sum of the volume of the first and second call sounds heard in the first zone ZN1 is greater than the sum of the volume of the first and second call sounds heard in the second zone ZN2.

[0105] According to this embodiment, the first filter group FG1 and the second filter group FG2 can reduce the volume of the call sound heard in the second zone ZN2. Therefore, the volume of the interference sound can be reduced in the second zone ZN2. In addition, the third filter group FG3 and the fourth filter group FG4 can reduce the volume of the interference sound heard in the first zone ZN1. Therefore, the privacy of the driver during a call can be easily secured, and the discomfort felt by the driver and passengers can be suppressed.

[0106] In the in-vehicle audio system 1 according to the first embodiment, the first zone ZN1 corresponds to the first seat 90R, which is the driver's seat of the vehicle 100, and the second zone ZN2 corresponds to the second seat 90L, which is the passenger seat of the vehicle 100. The first speaker set 41 is a headrest speaker set provided in a headrest 91R of the first seat 90R. The second speaker set 42 is a headrest speaker set provided in a headrest 91L of the second seat 90L.

[0107] According to this embodiment, the communication sound and the interference sound are outputted using speaker sets located close to the driver's head and the passenger's head, respectively, so that a more significant zoning effect can be obtained.

[0108] B: Variation The present invention is not limited to the above embodiment, and various modified examples can be adopted within the scope of the present invention. Specific modified examples are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined within a range that does not contradict each other. In the modified examples exemplified below, the symbols used in the above explanation are used for elements whose actions and functions are equivalent to those of the above embodiment, and detailed explanations of each are appropriately omitted.

[0109] B1: First modified example In the first embodiment, it was assumed that the first speaker set 41 and the second speaker set 42 have a total of four speakers, and 20 virtual microphones are virtually arranged in the entire zone including the first zone ZN1 and the second zone ZN2. However, the number of virtual microphones is not limited to 20, and the number of virtual microphones may be any number. In general, it is considered that the more the number of virtual microphones is increased, the more robust the designed zoning filter is improved, and the more easily the effect of the zoning filter can be obtained even against unexpected sound signals. However, it is preferable that the number of virtual microphones is a multiple of the number of speakers, 4. Hereinafter, the explanation will be continued assuming that the number of virtual microphones is M.

[0110] 6 is an explanatory diagram of speakers and virtual microphones arranged in a first zone ZN1 and a second zone ZN2 according to a first modified example. As shown in FIG. 6, a first speaker set 41 is arranged in the first zone ZN1, and M / 2 virtual microphones are arranged. The power output by each of the M / 2 virtual microphones is represented as p 1 , p 2 , …, p M / 4 , p M / 4+1 , p M / 4+2 , …, p M / 2 In the second zone ZN2, the second speaker set 42 is arranged, and M / 2 virtual microphones are arranged. The power output by each of the M / 2 virtual microphones is expressed as p M / 2+1 , p M / 2+2 , …, p 3M / 4 , p 3M / 4+1 , p 3M / 4+2 , …, p M Let us assume that.

[0111] Thus, in the example shown in Figure 6, the first speaker set 41 and the second speaker set 42 have a total of four speakers, and it is assumed that M virtual microphones are virtually placed in the entire zone including the first zone ZN1 and the second zone ZN2.

[0112] In addition, the number of speakers is not limited to four, and can be extended to L speakers. When the number of speakers is L and the number of virtual microphones is M, the characteristics of the first filter group FG1 and the second filter group FG2 are expressed by the transfer function matrix H M×L and the characteristic function g jammer and the objective function d jammer But, H M×L *g jammer =d jammer (9) The characteristic function g that satisfies the relationship jammer This can be obtained by calculating an approximation of

[0113] Transfer function matrix H M×Lis expressed by a matrix of M rows and L columns, and indicates the transfer characteristics from the inputs of the first filter group FG1 and the second filter group FG2 to the outputs of the M virtual microphones. jammer is expressed by a matrix of L rows and 1 column, and each element of the matrix of L rows and 1 column indicates the characteristics of the first filter FL1 and the second filter FL2 in the first filter group FG1 and the characteristics of the third filter FL3 and the fourth filter FL4 in the second filter group FG2, respectively. jammer is represented by a matrix with M rows and 1 column, and each element of the matrix with M rows and 1 column indicates a target value of power corresponding to a first interfering sound output from each of the M virtual microphones and a target value of power corresponding to a second interfering sound output from each of the M virtual microphones.

[0114] The characteristics of the third filter group FG3 and the fourth filter group FG4 are expressed by the transfer function matrix H M×L and the characteristic function g voice and the objective function d voice But, H M×L *g voice =d voice (10) The characteristic function g that satisfies the relationship voice This can be obtained by calculating an approximation of

[0115] Transfer function matrix H M×L is expressed by a matrix of M rows and L columns, and indicates the transfer characteristics from the inputs of the third filter group FG3 and the fourth filter group FG4 to the outputs of the M virtual microphones. voice is expressed by a matrix of L rows and 1 column, and each element of the matrix of L rows and 1 column indicates the characteristics of the fifth filter FL5 and the sixth filter FL6 in the third filter group FG3 and the characteristics of the seventh filter FL7 and the eighth filter FL8 in the fourth filter group FG4, respectively. voice is represented by a matrix with M rows and 1 column, and each element of the matrix with M rows and 1 column indicates a target value of power corresponding to a first call sound output from each of the M virtual microphones and a target value of power corresponding to a second call sound output from each of the M virtual microphones.

[0116] B2: Second variant FIG. 7 is a front view showing an example of the arrangement of the first speaker set 41 and the second speaker set 42 according to the second modified example. In the first embodiment, the first speaker set 41 is provided in the headrest 91R of the first seat 90R, which is the driver's seat, but as shown in FIG. 7, the first speaker set 41 may be provided in the seat back 92R of the first seat 90R. Also, in the first embodiment, the second speaker set 42 is provided in the headrest 91L of the second seat 90L, which is the passenger seat, but as shown in FIG. 7, the second speaker set 42 may be provided in the seat back 92L of the second seat 90L. In this modified example, the first speaker set 41 is arranged in the first zone ZN1A, and the second speaker set 42 is arranged in the second zone ZN2A.

[0117] Thus, in the in-vehicle audio system 1 according to the second modification, the first zone ZN1A corresponds to the first seat 90R of the vehicle 100, and the second zone ZN2A corresponds to the second seat 90L of the vehicle 100. The first speaker set 41 is a seatback speaker set provided in the seatback 92R of the first seat 90R. The second speaker set 42 is a seatback speaker set provided in the seatback 92L of the second seat 90L.

[0118] According to this embodiment, the communication sound and the interference sound are outputted using speaker sets located close to the driver's head and the passenger's head, respectively, so that a more significant zoning effect can be obtained.

[0119] B3: Third variant Fig. 8 is a front view showing an example of the arrangement of the first speaker set 41 and the second speaker set 42 according to the third modified example. In the first embodiment, the first speaker set 41 is provided in the headrest 91R of the first seat, but as shown in Fig. 8, the first speaker set 41 may be provided in a portion above the first seat 90R on the ceiling 101 of the vehicle 100. Also, in the first embodiment, the second speaker set 42 is provided in the headrest 91L of the second seat 90L, but as shown in Fig. 8, the second speaker set 42 may be provided in a portion above the second seat 90L on the ceiling 101. In this modified example, the first speaker set 41 is provided in the first zone ZN1B, and the second speaker set 42 is provided in the second zone ZN2B.

[0120] Thus, in the in-vehicle audio system 1 according to the third modified example, the first zone ZN1B corresponds to the first seat 90R of the vehicle 100, and the second zone ZN2B corresponds to the second seat 90L of the vehicle 100. The first speaker set 41 is a ceiling speaker set provided in a portion above the first seat 90R on the ceiling 101 of the vehicle 100. The second speaker set 42 is a ceiling speaker set provided in a portion above the second seat 90L on the ceiling 101.

[0121] According to this embodiment, the communication sound and the interference sound are outputted using speaker sets located close to the driver's head and the passenger's head, respectively, so that a more significant zoning effect can be obtained.

[0122] B4: Fourth variant In the first embodiment, the cutoff frequency of the first low-pass filter LP1 is set to 500 Hz, but the cutoff frequency is not limited to 500 Hz. The cutoff frequency may be within the range of 500 Hz plus or minus K% (for example, 20%).

[0123] B5: Fifth variant The first filter FL1 to the eighth filter FL8 are not limited to FIR filters, and other digital filters such as an IIR (Infinite Impulse Response) filter may be used as the first filter FL1 to the eighth filter FL8.

[0124] B6: 6th variant The in-car audio system 1 according to the first embodiment is mounted on a vehicle such as an automobile, but the in-car audio system 1 is also applicable to the fields of home audio and professional audio.

[0125] B7: 7th variant In the first embodiment, the second modified example, and the third modified example, the locations where the first speaker set 41 and the second speaker set 42 are arranged have been described, but the locations where the first speaker set 41 and the second speaker set 42 are arranged are not limited to the headrest, the seat back, and the ceiling. The first speaker set 41 may be arranged anywhere in the vehicle 100 as long as the driver's head is in a position that is included in the first zone ZN1. The second speaker set 42 may be arranged anywhere in the vehicle 100 as long as the passenger's head is in a position that is included in the second zone ZN2.

[0126] C: Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0127] A sound processing device according to one aspect (aspect 1) of the present disclosure comprises a first filter group including one or more filters that receive a first sound signal and control a first interfering sound output from a first speaker set including one or more speakers arranged in a first zone, and a second filter group including one or more filters that receive the first sound signal and control a second interfering sound output from a second speaker set including one or more speakers arranged in a second zone adjacent to the first zone, wherein the characteristics of the first filter group and the characteristics of the second filter group are set so that the sum of the volume of the first interfering sound and the volume of the second interfering sound heard in the second zone is greater than the sum of the volume of the first interfering sound and the volume of the second interfering sound heard in the first zone.

[0128] According to this embodiment, the first filter group and the second filter group can reduce the disturbance sound heard in the first zone. Therefore, the driver's discomfort can be suppressed. In addition, since the disturbance sound is difficult to hear in the first zone, the driver can lower the volume of the call sound.

[0129] A sound processing device according to one aspect (aspect 2) of the present disclosure further includes a third filter group including one or more filters to which a second sound signal is input and which controls a first playback sound output from the first speaker set, and a fourth filter group including one or more filters to which the second sound signal is input and which controls a second playback sound output from the second speaker set, wherein the characteristics of the third filter group and the characteristics of the fourth filter group are set so that the sum of the volume of the first playback sound and the volume of the second playback sound heard in the first zone is greater than the sum of the volume of the first playback sound and the volume of the second playback sound heard in the second zone.

[0130] According to this embodiment, the reproduced sound heard in the second zone can be reduced by the third filter group and the fourth filter group. Therefore, the discomfort felt by the passengers can be suppressed. In addition, since the reproduced sound is difficult to hear in the second zone, the volume of the interfering sound can be reduced. In particular, in a frequency band below 500 Hz, it is necessary to increase the volume of the interfering sound to obtain the effect of the interfering sound. However, according to this embodiment, zoning is also performed on the reproduced sound, so that the effect of the interfering sound in a frequency band below 500 Hz is complemented.

[0131] In a low-frequency emphasis signal generation method according to one aspect (aspect 3) of the present disclosure, it is assumed that the first speaker set and the second speaker set have a total of L speakers, and M virtual microphones are virtually arranged in the entire zone including the first zone and the second zone, and the characteristics of the first filter group and the characteristics of the second filter group are represented by a matrix with M rows and L columns, and a transfer function matrix H M×L and a characteristic function g represented by a matrix of L rows and 1 column, each element of the matrix of L rows and 1 column indicating the characteristics of each filter in the first filter group and the characteristics of each filter in the second filter group, respectively. jammer and a target function d 1 which is represented by a matrix of M rows and 1 column, and each element of the matrix of M rows and 1 column indicates a target value of the power corresponding to the first interfering sound output from each of the M virtual microphones and a target value of the power corresponding to the second interfering sound output from each of the M virtual microphones. jammer But, H M×L *g jammer =d jammer The characteristic function g that satisfies the relationship jammer This can be obtained by calculating an approximation of

[0132] According to this embodiment, it is possible to more easily design the first filter group and the second filter group so as to reduce the interfering sound heard in the first zone.

[0133] In a low-frequency emphasis signal generation method according to one aspect (aspect 4) of the present disclosure, it is assumed that the first speaker set and the second speaker set have a total of L speakers, and M virtual microphones are virtually arranged in the entire zone including the first zone and the second zone, and the characteristics of the third filter group and the characteristics of the fourth filter group are represented by a matrix with M rows and L columns, and a transfer function matrix H M×L and a characteristic function g represented by a matrix of L rows and 1 column, each element of the matrix of L rows and 1 column indicating the characteristics of each filter in the third filter group and the characteristics of each filter in the fourth filter group, respectively. voice and a target function d voice But, H M×L *g voice =d voice The characteristic function g that satisfies the relationship voice This can be obtained by calculating an approximation of

[0134] According to this embodiment, it is possible to more easily design the third filter group and the fourth filter group so as to reduce the reproduced sound heard in the second zone.

[0135] In a sound processing device according to one aspect (aspect 5) of the present disclosure, a first low-pass filter is provided in front of the first filter group and the second filter group, which outputs a first low-frequency signal by blocking high-frequency components of a first original signal, which is the original signal of the first interfering sound and the second interfering sound.

[0136] Since the zoning filter is effective in a relatively low frequency range, there is no problem in limiting the frequency range processed by the zoning filter to a relatively low frequency range. By limiting the frequency range processed by the zoning filter to a range below a predetermined frequency, the amount of calculation of the zoning filter can be reduced. Therefore, according to this embodiment, it is possible to perform calculations with higher accuracy without significantly increasing the processing load of the processor.

[0137] In a sound processing device according to one aspect (aspect 6) of the present disclosure, a second low-pass filter is provided in front of the third filter group and the fourth filter group, which outputs a second low-frequency signal by blocking high-frequency components of a second original signal, which is the original signal of the first reproduced sound and the second reproduced sound.

[0138] Since the zoning filter is effective in a relatively low frequency range, there is no problem in limiting the frequency range processed by the zoning filter to a relatively low frequency range. By limiting the frequency range processed by the zoning filter to a range below a predetermined frequency, the amount of calculation of the zoning filter can be reduced. Therefore, according to this embodiment, it is possible to perform calculations with higher accuracy without significantly increasing the processing load of the processor.

[0139] In a sound processing device according to one aspect (aspect 7) of the present disclosure, a first low-pass filter is provided in front of the first filter group and the second filter group, which outputs a first low-frequency signal as the first sound signal by blocking high-frequency components of a first original signal, which is an original signal of the first interfering sound and the second interfering sound, and the first original signal is separated into the first low-frequency signal and a first high-frequency signal by the first low-pass filter and a first high-pass filter provided in parallel with the first low-pass filter, and the first low-frequency signal that has passed through the first filter group is combined with a signal in which the amplitude of the first high-frequency signal has been adjusted by a first amplifier group provided in the rear of the first high-pass filter, and then input to the first speaker set, and the first low-frequency signal that has passed through the second filter group is combined with a signal in which the amplitude of the first high-frequency signal has been adjusted by a second amplifier group provided in the rear of the first high-pass filter, and then input to the first speaker set. The second original signal is input to the second speaker set, and is separated into the second low-frequency signal and the second high-frequency signal by the second low-pass filter and a second high-pass filter arranged in parallel with the second low-pass filter, and the signal of the second low-frequency signal that has passed through the third filter group is combined with a signal in which the amplitude of the second high-frequency signal has been adjusted by a third amplifier group arranged downstream of the second high-pass filter, and then input to the first speaker set, and the signal of the second low-frequency signal that has passed through the fourth filter group is combined with a signal in which the amplitude of the second high-frequency signal has been adjusted by a fourth amplifier group arranged downstream of the second high-pass filter, and then input to the second speaker set, and the cutoff frequency of the first low-pass filter, the cutoff frequency of the first high-pass filter, the cutoff frequency of the second low-pass filter, and the cutoff frequency of the second high-pass filter are substantially equal to each other.

[0140] According to this aspect, the frequency bands processed by the first filter group, the second filter group, the third filter group, and the fourth filter group are the same, making it easier to design the first filter group, the second filter group, the third filter group, and the fourth filter group.

[0141] In the sound processing device according to one aspect (aspect 8) of the present disclosure, the first filter group and the second filter group are configured with FIR filters.

[0142] According to this embodiment, the amplitude and phase of the first interfering sound generated from the first speaker set and the amplitude and phase of the second interfering sound generated from the second speaker set can be precisely controlled. As a result, the volume of the interfering sound can be reduced, and discomfort felt by the driver and passengers can be suppressed.

[0143] In the sound processing device according to one aspect (aspect 9) of the present disclosure, the third filter group and the fourth filter group are configured with FIR filters.

[0144] According to this embodiment, the amplitude and phase of the first reproduction sound generated from the first speaker set and the amplitude and phase of the second reproduction sound generated from the second speaker set can be precisely controlled. As a result, the volume of the interference sound can be reduced, and discomfort felt by the driver and passengers can be suppressed.

[0145] An in-vehicle audio system according to one embodiment (embodiment 10) of the present disclosure comprises a first speaker set arranged in a first zone, a second speaker set arranged in a second zone adjacent to the first zone, and a sound processing device having a first filter group that controls a first interference sound output from the first speaker set, a second filter group that controls a second interference sound output from the second speaker set, a third filter group that controls a first reproduced sound output from the first speaker set, and a fourth filter group that controls a second reproduced sound output from the second speaker set, wherein the characteristics of the first filter group and the characteristics of the second filter group are set so that the sum of the volume of the first interference sound and the volume of the second interference sound heard in the second zone is greater than the sum of the volume of the first interference sound and the volume of the second interference sound heard in the first zone, and the characteristics of the third filter group and the characteristics of the fourth filter group are set so that the sum of the volume of the first reproduced sound and the volume of the second reproduced sound heard in the first zone is greater than the sum of the volume of the first reproduced sound and the volume of the second reproduced sound heard in the second zone.

[0146] According to this aspect, the first filter group and the second filter group can reduce the volume of the reproduced sound heard in the second zone. Therefore, the volume of the disturbing sound can be reduced in the second zone. Also, the third filter group and the fourth filter group can reduce the disturbing sound heard in the first zone. Therefore, the privacy of the driver during a call can be easily secured, and the discomfort felt by the driver and passengers can be suppressed.

[0147] In an in-vehicle audio system according to one aspect (aspect 11) of the present disclosure, the first zone corresponds to the driver's seat of the vehicle, the second zone corresponds to the passenger seat of the vehicle, the first speaker set is a headrest speaker set provided in a headrest of the driver's seat, and the second speaker set is a headrest speaker set provided in a headrest of the passenger seat.

[0148] According to this aspect, the reproduced sound and the interfering sound are outputted using speaker sets located close to the driver's head and the passenger's head, respectively, so that a more significant zoning effect can be obtained.

[0149] In an in-vehicle audio system according to one aspect (aspect 12) of the present disclosure, the first zone corresponds to the driver's seat of the vehicle, the second zone corresponds to the passenger seat of the vehicle, the first speaker set is a seatback speaker set provided on the seatback of the driver's seat, and the second speaker set is a seatback speaker set provided on the seatback of the passenger seat.

[0150] According to this aspect, the reproduced sound and the interfering sound are outputted using speaker sets located close to the driver's head and the passenger's head, respectively, so that a more significant zoning effect can be obtained.

[0151] In an in-vehicle audio system according to one embodiment (embodiment 13) of the present disclosure, the first zone corresponds to the driver's seat of the vehicle, the second zone corresponds to the passenger seat of the vehicle, the first speaker set is a ceiling speaker set provided in a portion of the ceiling of the vehicle above the driver's seat, and the second speaker set is a ceiling speaker set provided in a portion of the ceiling of the vehicle above the passenger seat.

[0152] According to this aspect, the reproduced sound and the interfering sound are outputted using speaker sets located close to the driver's head and the passenger's head, respectively, so that a more significant zoning effect can be obtained. [Explanation of symbols]

[0153] 1...vehicle audio system, 30...sound processing device, 41...first speaker set, 42...second speaker set, 90R...first seat (driver's seat), 90L...second seat (passenger's seat), 91L, 91R...headrest, 92L, 92R...seat back, 100...vehicle, 101...ceiling, AG1...first amplifier group, AG2...second amplifier group, AG3...third amplifier group, AG4...fourth amplifier group, FG1...first filter group, FG2...second filter group, FG3...third filter filter group, FG4...fourth filter group, HP1...first high-pass filter, HP2...second high-pass filter, LP1...first low-pass filter, LP2...second low-pass filter, M1~M20...virtual microphones, SH1...first high-frequency signal, SH2...second high-frequency signal, SL1...first low-frequency signal, SL2...second low-frequency signal, SO1...first original signal, SO2...second original signal, ZN1, ZN1A, ZN1B...first zone, ZN2, ZN2A, ZN2B...second zone.

Claims

1. a first filter group including one or more filters that receive a first sound signal and control a first interference sound output from a first speaker set including one or more speakers arranged in a first zone; a second filter group including one or more filters that control a second interference sound output from a second speaker set including one or more speakers that are arranged in a second zone adjacent to the first zone and to which the first sound signal is input; Equipped with The characteristics of the first filter group and the characteristics of the second filter group are set so that the sum of the volume of the first interference sound and the volume of the second interference sound heard in the second zone is greater than the sum of the volume of the first interference sound and the volume of the second interference sound heard in the first zone. Sound processing device.

2. a third filter group including one or more filters to which a second sound signal is input and which controls a first reproduction sound output from the first speaker set; a fourth filter group including one or more filters to which the second sound signal is input and which controls a second reproduction sound output from the second speaker set; Further equipped with the characteristics of the third filter group and the characteristics of the fourth filter group are set so that the sum of the volume of the first reproduction sound and the volume of the second reproduction sound heard in the first zone is greater than the sum of the volume of the first reproduction sound and the volume of the second reproduction sound heard in the second zone. The sound processing device according to claim 1 .

3. the first speaker set and the second speaker set have a total of L speakers; It is assumed that M virtual microphones are virtually arranged in an entire zone including the first zone and the second zone, The characteristics of the first filter group and the characteristics of the second filter group are A transfer function matrix H, which is represented by a matrix of M rows and L columns and indicates transfer characteristics from the inputs of the first filter group and the second filter group to the outputs of the M virtual microphones. Ｍ×Ｌ and, A characteristic function g is expressed by a matrix of L rows and 1 column, and each element of the matrix of L rows and 1 column indicates the characteristic of each filter in the first filter group and the characteristic of each filter in the second filter group. ｊａｍｍｅｒ and, A target function d is represented by a matrix with M rows and one column, and each element of the matrix with M rows and one column indicates a target value of power corresponding to the first interfering sound output from each of the M virtual microphones and a target value of power corresponding to the second interfering sound output from each of the M virtual microphones. ｊａｍｍｅｒ But, H Ｍ×Ｌ *g ｊａｍｍｅｒ =d ｊａｍｍｅｒ The characteristic function g that satisfies the relationship ｊａｍｍｅｒ By calculating the approximate solution of The sound processing device according to claim 1 .

4. the first speaker set and the second speaker set have a total of L speakers; It is assumed that M virtual microphones are virtually arranged in an entire zone including the first zone and the second zone, The characteristics of the third filter group and the characteristics of the fourth filter group are A transfer function matrix H, which is represented by a matrix of M rows and L columns and indicates transfer characteristics from the inputs of the third filter group and the fourth filter group to the outputs of the M virtual microphones. Ｍ×Ｌ and, A characteristic function g is expressed by a matrix of L rows and 1 column, and each element of the matrix of L rows and 1 column indicates the characteristic of each filter in the third filter group and the characteristic of each filter in the fourth filter group. ｖｏｉｃｅ and, A target function d is represented by a matrix with M rows and one column, and each element of the matrix with M rows and one column indicates a target value of power corresponding to the first reproduced sound output from each of the M virtual microphones and a target value of power corresponding to the second reproduced sound output from each of the M virtual microphones. ｖｏｉｃｅ But, H Ｍ×Ｌ *g ｖｏｉｃｅ =d ｖｏｉｃｅ The characteristic function g that satisfies the relationship ｖｏｉｃｅ By calculating the approximate solution of The sound processing device according to claim 2 .

5. a first low-pass filter is provided in front of the first filter group and the second filter group, the first low-pass filter outputting a first low-frequency signal by blocking high-frequency components of a first original signal which is an original signal of the first interference sound and the second interference sound; The sound processing device according to claim 1 .

6. a second low-pass filter is provided in front of the third filter group and the fourth filter group, the second low-pass filter being configured to output a second low-frequency signal by blocking high-frequency components of a second original signal that is an original signal of the first reproduced sound and the second reproduced sound; The sound processing device according to claim 2 .

7. a first low-pass filter is provided in front of the first filter group and the second filter group, the first low-pass filter cutting off high-frequency components of a first original signal that is an original signal of the first interference sound and the second interference sound, thereby outputting a first low-frequency signal as the first sound signal; the first original signal is separated into the first low-frequency signal and a first high-frequency signal by the first low-pass filter and a first high-pass filter provided in parallel with the first low-pass filter; The first low-frequency signal that has passed through the first filter group is mixed with a signal obtained by adjusting the amplitude of the first high-frequency signal by a first amplifier group provided in a subsequent stage of the first high-pass filter, and then input to the first speaker set. The first low-frequency signal that has passed through the second filter group is mixed with a signal obtained by adjusting the amplitude of the first high-frequency signal by a second amplifier group provided downstream of the first high-pass filter, and then input to the second speaker set. the second original signal is separated into the second low frequency signal and the second high frequency signal by the second low pass filter and a second high pass filter provided in parallel with the second low pass filter; The second low-frequency signal that has passed through the third filter group is mixed with a signal obtained by adjusting the amplitude of the second high-frequency signal by a third amplifier group provided in a subsequent stage of the second high-pass filter, and then input to the first speaker set. The second low-frequency signal that has passed through the fourth filter group is mixed with a signal obtained by adjusting the amplitude of the second high-frequency signal by a fourth amplifier group provided in a subsequent stage of the second high-pass filter, and then input to the second speaker set. a cutoff frequency of the first low-pass filter, a cutoff frequency of the first high-pass filter, a cutoff frequency of the second low-pass filter, and a cutoff frequency of the second high-pass filter are substantially equal to each other; The sound processing device according to claim 6 .

8. the first filter group and the second filter group are constituted by FIR filters; The sound processing device according to claim 1 .

9. the third filter group and the fourth filter group are constituted by FIR filters; The sound processing device according to claim 2 .

10. a first set of speakers disposed in a first zone; a second set of speakers disposed in a second zone adjacent to the first zone; a sound processing device having a first filter group that controls a first interfering sound output from the first speaker set, a second filter group that controls a second interfering sound output from the second speaker set, a third filter group that controls a first reproduced sound output from the first speaker set, and a fourth filter group that controls a second reproduced sound output from the second speaker set; Equipped with the characteristics of the first filter group and the characteristics of the second filter group are set so that a sum of a volume of the first interference sound and a volume of the second interference sound heard in the second zone is greater than a sum of a volume of the first interference sound and a volume of the second interference sound heard in the first zone, the characteristics of the third filter group and the characteristics of the fourth filter group are set so that the sum of the volume of the first reproduction sound and the volume of the second reproduction sound heard in the first zone is greater than the sum of the volume of the first reproduction sound and the volume of the second reproduction sound heard in the second zone. In-car audio system.

11. the first zone corresponds to a driver's seat of a vehicle, and the second zone corresponds to a passenger's seat of the vehicle; the first speaker set is a headrest speaker set provided in a headrest of the driver's seat, The second speaker set is a headrest speaker set provided in a headrest of the passenger seat.

11. The vehicle audio system of claim 10.

12. the first zone corresponds to a driver's seat of a vehicle, and the second zone corresponds to a passenger's seat of the vehicle; the first speaker set is a seat back speaker set provided on a seat back of the driver's seat, The second speaker set is a seat back speaker set provided in a seat back of the passenger seat.

11. The vehicle audio system of claim 10.

13. the first zone corresponds to a driver's seat of a vehicle, and the second zone corresponds to a passenger's seat of the vehicle; the first speaker set is a ceiling speaker set provided in a portion above the driver's seat on a ceiling of the vehicle, the second speaker set is a ceiling speaker set provided in a portion of the ceiling above the passenger seat, 11. The vehicle audio system of claim 10.

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