Audio system

Abstract

The system provides an "audio system" that outputs a masking sound at an appropriate level to mask the music being listened to by the other user. [Solution] The audio signal processing device includes: a crosstalk detection unit 1 that extracts the component of the second audio signal output to the second seat speaker from the microphone output as a crosstalk signal; a noise detection unit 2 that extracts the component of the microphone output that does not include the component of the second audio signal or the component of the output sound of the first seat speaker but includes the component of ambient noise as a noise signal; a gain calculation unit 3 that calculates a gain adjustment amount for the mask noise signal so that the mask noise signal becomes larger by a predetermined amount than the difference in magnitude between the crosstalk signal and the noise signal; a gain adjustment unit 42 that adjusts the gain of the mask noise signal with the calculated gain adjustment amount; and a combining unit that combines the gain-adjusted mask noise signal and the first audio signal and outputs them to the first seat speaker.

Description

Technical Field

[0001] The present invention relates to an audio system.

Background Art

[0002] As a technology for controlling the sound field so that the target sound to be listened to by the user, which is the sound to be listened to, cannot be heard by other users, while outputting the target sound to be listened to from a speaker to the first area where the user is located, a masking sound, which is a noise sound that inhibits the listening of the target sound to be listened to, is output from a speaker to the second area, which is an area where it is desired to suppress the listening of the target sound to be listened to, such as the area where others are located (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when a user in the driver's seat and a user in the passenger seat listen to different music in a vehicle, it is desirable that the music being listened to by one user can be heard by that user while the music being listened to by the other user cannot be heard. Therefore, it is conceivable to output a masking sound that masks the music being listened to by the other user to one user. However, environmental noise sounds such as road noise sounds and engine noise sounds are generated inside the vehicle, and this environmental noise sound also functions as a masking sound that masks the music being listened to by the other user for one user. Also, the level of this environmental noise sound changes according to the driving state of the vehicle.

[0005] Therefore, if the mask sound is not output at an appropriate level corresponding to fluctuations in ambient noise, the mask sound level will be inappropriate, either excessive or insufficient. Therefore, the present invention aims to provide a user with a mask sound in an automobile that masks the music being listened to by other users, at an appropriate level corresponding to the ambient noise level. [Means for solving the problem]

[0006] To achieve the above objectives, the present invention provides an audio system comprising: a first-seat speaker positioned near the first seat of an automobile; a microphone positioned near the head of a user seated in the first seat; a second-seat speaker positioned near the second seat of an automobile; a first-seat sound source that outputs a first audio signal; a mask noise sound source that outputs a predetermined noise signal as a mask noise signal; an audio signal processing device that synthesizes the first audio signal output by the first-seat sound source and the mask noise signal output by the mask noise sound source and outputs the combined signal to the first-seat speaker; and a second-seat sound source that outputs a second audio signal output from the second-seat speaker.

[0007] The audio signal processing device includes: a crosstalk detection unit that extracts the component of the second audio signal included in the output of the microphone as a crosstalk signal; a noise detection unit that extracts a component in the output of the microphone that does not include the component of the second audio signal and the component of the output sound of the first seat speaker, but includes a component of noise unrelated to the audio system, as a noise signal; a gain calculation unit that calculates a gain adjustment amount for the mask noise signal so that the mask noise signal becomes larger by a predetermined amount than the difference in magnitude between the crosstalk signal and the noise signal; a gain adjustment unit that adjusts the gain of the mask noise signal output by the mask noise sound source by the gain adjustment amount calculated by the gain calculation unit; and a synthesis unit that synthesizes the mask noise signal whose gain has been adjusted by the gain adjustment unit and the first audio signal output by the first seat sound source and outputs it to the first seat speaker.

[0008] In this audio system, the crosstalk detection unit may generate the crosstalk signal by removing the noise signal component and the signal component output by the synthesis unit to the first seat speaker from the output of the microphone. Furthermore, in each of the above audio systems, the noise detection unit may generate the noise signal by removing the components of the second audio signal and the components of the signal output by the combining unit to the first seat speaker from the output of the microphone. Furthermore, in order to achieve the above objectives, the present invention provides an audio system comprising: a first-seat speaker positioned near the first seat of an automobile; a second-seat speaker positioned near the second seat of an automobile; a first-seat sound source that outputs a first audio signal; a mask noise sound source that outputs a predetermined noise signal as a mask noise signal; an audio signal processing device that synthesizes the first audio signal output by the first-seat sound source and the mask noise signal output by the mask noise sound source and outputs it to the first-seat speaker; a second-seat sound source that outputs a second audio signal output from the second-seat speaker; and a sensor that detects the behavior of the automobile. The audio signal processing device is The system includes: a crosstalk detection unit that generates a crosstalk signal by convolving the second audio signal with a transfer function obtained in advance from the second seat sound source to the position of the user's head seated in the first seat; a noise detection unit that generates a noise signal representing noise obtained according to the relationship between the behavior detected by the sensor and noise unrelated to the audio system, obtained in advance; a gain calculation unit that calculates a gain adjustment amount for the mask noise signal so that the mask noise signal becomes larger by a predetermined amount than the difference in magnitude between the crosstalk signal and the noise signal; a gain adjustment unit that adjusts the gain of the mask noise signal output by the mask noise sound source using the gain adjustment amount calculated by the gain calculation unit; and a synthesis unit that synthesizes the mask noise signal whose gain has been adjusted by the gain adjustment unit and the first audio signal output by the first seat sound source and outputs it to the first seat speaker.

[0009] More specifically, the behavior detected by the sensor may be the acceleration of vibration of the automobile, and the noise may be road noise. In this case, each of the above audio systems may, in the gain calculation unit, calculate a gain adjustment amount for the mask noise signal such that the mask noise signal becomes a predetermined amount greater than the difference in magnitude between the crosstalk signal and the noise signal for each predetermined band. In this case, the gain adjustment unit adjusts the gain of the mask noise signal output by the mask noise sound source for each band using the gain adjustment amount calculated by the gain calculation unit for that band.

[0010] Here, the audio system may, in the gain calculation unit, calculate the gain adjustment amount for the mask noise signal for each of the frequency bands such that the perceived loudness of the combined sound of the sound corresponding to the mask noise signal and the sound corresponding to the noise signal is perceived to be a predetermined level louder than the perceived loudness of the sound corresponding to the noise signal alone.

[0011] With the audio system described above, the level of mask noise that masks the second audio signal intended for the second-seat user from the first-seat user can be adjusted to an appropriate level that corresponds to both the level of environmental noise such as road noise not caused by the audio system and the level at which the second audio signal for the second seat leaks into the first seat. [Effects of the Invention]

[0012] As described above, according to the present invention, in an automobile, a mask sound that masks the music being listened to by other users can be output to the user at an appropriate level according to the ambient noise level. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows the configuration of an audio system according to an embodiment of the present invention. [Figure 2] This figure shows an example of the arrangement of a microphone and speaker according to an embodiment of the present invention. [Figure 3] It is a diagram showing the configuration of the crosstalk detection unit according to an embodiment of the present invention. [Figure 4] It is a diagram showing the configuration of the noise detection unit according to an embodiment of the present invention. [Figure 5] It is a diagram showing the configuration of the gain adjustment unit for each band and the mixer unit according to an embodiment of the present invention. [Figure 6] It is a diagram showing another configuration example of the audio system according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described. Fig. 1 shows the configuration of the audio system according to this embodiment. The audio system is a system mounted on an automobile. As shown in the figure, it includes a microphone MC_D for the driver's seat, a microphone MC_P for the passenger seat, an audio device AEQ, a speaker SP_D for the driver's seat, a speaker SP_P for the passenger seat, a mask noise sound source MNS, an audio signal processing device ASP_D for the driver's seat, and an audio signal processing device ASP_P for the passenger seat.

[0015] Here, as shown in Fig. 2, the microphone MC_D for the driver's seat and the speaker SP_D for the driver's seat are arranged at positions near the head of the user sitting in the driver's seat, such as on the headrest of the driver's seat, and the microphone MC_P for the passenger seat and the speaker SP_P for the passenger seat are arranged at positions near the head of the user sitting in the passenger seat, such as on the headrest of the passenger seat.

[0016] Returning to Fig. 1, the audio device AEQ functions simultaneously as a sound source AS_D for the driver's seat and a sound source AS_P for the passenger seat. Here, the sound source AS_D for the driver's seat, the audio signal processing device ASP_D for the driver's seat, and the speaker SP_D for the driver's seat are configured corresponding to the driver's seat, and the sound source AS_P for the passenger seat, the audio signal processing device ASP_P for the passenger seat, and the speaker SP_P for the passenger seat are configured corresponding to the passenger seat.

[0017] And in such a configuration, the mask noise sound source MNS outputs a noise signal of a predetermined level as a mask noise signal MN. As this mask noise signal MN, for example, a pink noise signal or a red noise (brown noise) signal can be used. The audio signal such as music output from the driver's seat sound source AS_D is combined with the mask noise signal MN output by the mask noise sound source MNS by the driver's seat audio signal processing device ASP_D and output to the driver's seat speaker SP_D. The audio signal such as music output from the passenger seat sound source AS_P is combined with the mask noise signal MN output by the mask noise sound source MNS by the passenger seat audio signal processing device ASP_P and output to the passenger seat speaker SP_P.

[0018] Next, the driver's seat audio signal processing device ASP_D and the passenger seat audio signal processing device ASP_P have the same configuration and perform similar operations. Therefore, the configuration of the driver's seat audio signal processing device ASP_D will be described as a representative. As shown in the figure, the audio signal processing device ASP_D includes a crosstalk detection unit 1, a noise detection unit 2, a gain calculation unit 3, a per-band gain adjustment unit 4, and a mixer unit 5. The per-band gain adjustment unit 4 is a so-called equalizer, and adjusts the gain of the mask noise signal MN output by the mask noise sound source MNS according to the gain control signal G output by the gain calculation unit 3 for each 1 / 3 octave band and outputs it to the mixer unit 5. Taking the output of the driving sound source AS_D as the audio signal S_AS, the mixer unit 5 combines the output of the per-band gain adjustment unit 4 and the audio signal S_AS and outputs the combined signal as the output signal SP_OUT to the driver's seat speaker SP_D. Taking the output of the passenger seat sound source AS_P as the audio signal T_AS and the output of the driver's seat microphone MC_D as the microphone input signal Min, the crosstalk detection unit 1 extracts the component of the audio signal T_AS in the microphone input signal Min as the crosstalk signal CT. The noise detection unit 2 extracts the components of the microphone input signal Min, excluding the audio signal T_AS and the output signal SP_OUT, as the noise signal NZ. Here, this noise signal NZ includes components of environmental noise, such as road noise, that are not related to the audio system. The gain calculation unit 3 calculates the gain of the band-by-band gain adjustment unit 4 for each 1 / 3 octave band, based on the difference in levels between the crosstalk signal CT and the noise signal NZ, such that the mask noise signal MN output by the band-by-band gain adjustment unit 4 becomes a predetermined level larger. The unit then outputs a gain control signal G to control the gain of the band-by-band gain adjustment unit 4 based on the calculated gain.

[0019] Next, Figure 3 shows the configuration of the crosstalk detection unit 1. As shown in the figure, the crosstalk detection unit 1 includes a first adaptive filter 11, a first adder 12, a second adaptive filter 13, and a second adder 14. The first adaptive filter 11 is an adaptive filter that takes the noise signal NZ as input, and the first adder 12 subtracts the output of the first adaptive filter 11 from the microphone input signal Min and outputs the result. The first adaptive filter 11 then sets its own transfer function (filter coefficients) so that the output of the first adder 12 is minimized. Therefore, the output of the first adder 12 is the signal obtained by removing the noise signal NZ component from the microphone input signal Min. Next, the second adaptive filter 13 is an adaptive filter that takes the output signal SP_OUT output by the mixer unit 5 as its input, and the second adder 14 subtracts the output of the second adaptive filter 13 from the output of the first adder 12 and outputs the result. Then, the second adaptive filter 13 sets its own transfer function (filter coefficients) so that the output of the second adder 14 is minimized. Therefore, the output of the second adder 14 is the signal obtained by removing the noise signal NZ component and the output signal SP_OUT component (the component leaking from the driver's seat speaker SP_D) from the microphone input signal Min, that is, the signal representing the audio signal T_AS component (crosstalk component) in the microphone input signal Min, and this signal is output as the crosstalk signal CT.

[0020] Next, Figure 4 shows the configuration of the noise detection unit 2. As shown in the figure, the noise detection unit 2 includes a third adaptive filter 21, a third adder 32, a fourth adaptive filter 23, and a fourth adder 24. The third adaptive filter 21 is an adaptive filter that takes the audio signal T_AS as input, and the third adder 32 subtracts the output of the third adaptive filter 21 from the microphone input signal Min and outputs the result. Then, the third adaptive filter 21 sets its own transfer function (filter coefficients) so that the output of the third adder 32 is minimized. Therefore, the output of the third adder 32 is the signal obtained by removing the component of the audio signal T_AS from the microphone input signal Min. Next, the fourth adaptive filter 23 is an adaptive filter that takes the output signal SP_OUT output by the mixer unit 5 as its input, and the fourth adder 24 subtracts the output of the fourth adaptive filter 23 from the output of the third adder 32 and outputs the result. Then, the fourth adaptive filter 23 sets its own transfer function (filter coefficients) so that the output of the fourth adder 24 is minimized. Therefore, the output of the fourth adder 24 is the signal obtained by removing the components of the audio signal T_AS (the leakage sound component from the output of the passenger-side sound source AS_P) and the components of the output signal SP_OUT (the feedback component from the driver's-side speaker SP_D) from the microphone input signal Min. In other words, it is the signal containing the environmental noise component from the microphone input signal Min, and this signal is output as the noise signal NZ.

[0021] Next, Figure 5 shows the configuration of the gain calculation unit 3 and the gain adjustment unit 4 for each bandwidth. As shown in the figure, the gain calculation unit 3 includes a noise band division unit 31, a noise power calculation unit 32, a crosstalk band division unit 33, a crosstalk power calculation unit 34, a gain calculation unit 35, and a loudness compensation unit 36. The noise band division unit 31 divides the noise signal NZ into 1 / 3 octave bands, and the noise power calculation unit 32 calculates the power of the noise signal NZ for each divided band. The crosstalk band division unit 33 divides the crosstalk signal CT into 1 / 3 octave bands, and the crosstalk power calculation unit 34 calculates the power of the crosstalk signal CT for each divided band. The gain calculation unit 35 calculates the gain of the band-by-band gain adjustment unit 4 so that the mask noise signal MN output by the band-by-band gain adjustment unit 4 is greater than the difference in levels between the crosstalk signal CT and the noise signal NZ by a predetermined level (for example, 1 dB) for each band. In other words, the gain of the band-by-band gain adjustment unit 4 is calculated so that the sum of the mask noise signal MN and the noise signal NZ output by the band-by-band gain adjustment unit 4 is greater than the level of the crosstalk signal CT by a predetermined level (for example, 1 dB). Here, the levels of each band of the mask noise signal MN output by the mask noise sound source MNS, which is necessary for this calculation, are set in advance in the gain calculation unit 35. The loudness compensation unit 36 ​​compensates for the difference in perceived loudness for each frequency band, and corrects the gain calculated by the gain calculation unit 35 so that the sum of the magnitudes of the mask noise signal MN and the noise signal NZ, as perceived by a user seated in the driver's seat, is greater than the magnitude of the crosstalk signal CT in each frequency band. This corrected gain is then output as a gain control signal G to the frequency band gain adjustment unit 4. Next, the gain adjustment unit 4 for each band includes a mask noise band division unit 41 and a gain adjustment unit 42. The mask noise band division unit 41 divides the mask noise signal MN output by the mask noise sound source MNS into 1 / 3 octave bands. The gain adjustment unit adjusts the gain of the mask noise signal MN for each divided band according to the gain control signal G input from the loudness compensation unit 36. The adjusted mask noise signals MN for each band are then combined and output to the mixer unit 5.

[0022] The above describes the ASP_D audio signal processing unit for the driver's seat. Here, the description of the passenger-side audio signal processing unit ASP_P is the same as the description of the driver-side audio signal processing unit ASP_D above, but with the driver's seat and passenger seat swapped, the driver's seat microphone MC_D replaced with the passenger-side microphone MC_P, the driver's seat speaker SP_D replaced with the passenger-side speaker SP_P, and the driver's seat sound source AS_D replaced with the passenger-side sound source AS_P.

[0023] Embodiments of the present invention have been described above. Incidentally, the audio system described above may also be configured as shown in Figure 6. As shown in the diagram, this audio system is equipped with a sensor 601 that detects the acceleration of vibrations in the vehicle. Then, in the crosstalk detection unit 1 of the audio signal processing device AP_D for the driver's seat, the transfer function from the passenger-side sound source AS_P to the position of the user's head seated in the driver's seat via the passenger-side speaker SP_P, which has been pre-trained, is convolved into the output of the passenger-side sound source AS_P to generate a crosstalk signal CT. Similarly, in the crosstalk detection unit 1 of the audio signal processing device AP_P for the passenger seat, the transfer function from the driver-side sound source AS_D to the position of the user's head seated in the passenger seat via the driver-side speaker SP_D, which has been pre-trained, is convolved into the output of the driver-side sound source AS_D to generate a crosstalk signal CT.

[0024] Here, the transfer function from the passenger-side sound source AS_P to the position of the user's head seated in the driver's seat may be pre-trained as the transfer function from the output of the passenger-side sound source AS_P through the passenger-side speaker SP_P to the driver-side microphone MC_D, and the transfer function from the driver-side sound source AS_D to the position of the user's head seated in the passenger seat may be pre-trained as the transfer function from the output of the driver-side sound source AS_D through the driver-side speaker SP_D to the passenger-side microphone MC_P.

[0025] Furthermore, the noise detection unit 2 of the audio signal processing units AP_D and ASP_P estimates environmental noise from the detected values ​​of sensor 601 and outputs a noise signal NZ representing the estimated environmental noise. The estimation of environmental noise from the detected values ​​of sensor 601 is performed by estimating road noise from the acceleration of vehicle vibration detected by sensor 601, according to the relationship between the acceleration of vehicle vibration and road noise that has been pre-trained.

[0026] For pre-training the relationship between vibration acceleration and road noise, an adaptive filter that converts acceleration to road noise can be adapted such that the difference between the actual road noise picked up by a suitable microphone and the output of the adaptive filter is minimized. In this case, the output of the adaptive filter, which takes the vehicle vibration acceleration detected by sensor 601 as input, is used as the estimated road noise. Alternatively, as a pre-training method for the relationship between vibration acceleration and road noise, a table may be created by first determining the correspondence between vibration acceleration and actual road noise picked up by a suitable microphone. In this case, the road noise associated with the vehicle vibration acceleration detected by sensor 601 in the table is considered the estimated road noise.

[0027] In this case, the noise detection unit 2 may further detect environmental noise that includes the estimated engine noise. In this case, engine noise is estimated by providing a sensor 601 that detects the engine speed of the automobile, and estimating the engine noise from the engine speed detected by the sensor 601 according to a pre-learned relationship between engine speed and engine noise. Here, this pre-training can be performed by adapting an adaptive filter that converts periodic waves (such as sine waves) that have the same rotation and period as the engine speed, or a period of 1 / number of cylinders of the engine speed's period, into engine noise, so that the difference between the actual engine noise picked up by the microphone and the output of the adaptive filter is minimized. In this case, the output of the adaptive filter that takes as input a periodic wave (such as a sine wave) that has the same rotation and period as the engine speed detected by sensor 601, or a period of 1 / number of cylinders of the engine speed's period, is considered the estimated engine noise. According to the audio system shown in Figure 6, the microphone MC_D for the driver's seat and the microphone MC_P for the passenger seat can be made unnecessary, at least during actual operation. Here, one of the crosstalk detection unit 1 and noise detection unit 2 of the audio system shown in Figure 6 may be replaced with the corresponding detection unit of the crosstalk detection unit 1 and noise detection unit 2 of the audio system shown in Figure 2.

[0028] As described above, according to this embodiment, by designating one of the driver's seat and the passenger seat as the first seat and the other as the second seat, the level of mask noise that masks the second audio signal intended for the second seat user for the first seat user can be adjusted to an appropriate level corresponding to both the level of environmental noise such as road noise not caused by the audio system and the level of crosstalk caused by the second audio signal for the second seat leaking into the first seat.

[0029] In addition, the driver's seat and passenger seat in the above embodiments may be replaced with any two seats in the vehicle. [Explanation of Symbols]

[0030] 1…Crosstalk detection unit, 2…Noise detection unit, 3…Gain calculation unit, 4…Gain adjustment unit for each band, 5…Mixer unit, 11…First adaptive filter, 12…First adder, 13…Second adaptive filter, 14…Second adder, 21…Third adaptive filter, 23…Fourth adaptive filter, 24…Fourth adder, 31…Noise band division unit, 32…Third adder, 32…Noise power calculation unit, 33…Crosstalk band division unit, 34…Crosstalk power calculation unit Section 35...Gain calculation section, 36...Loudness compensation section, 41...Mask noise band division section, 42...Gain adjustment section, 601...Sensor, AEQ...Audio device, ASP_D...Audio signal processing device for the driver's seat, ASP_P...Audio signal processing device for the passenger seat, MC_D...Microphone for the driver's seat, MC_P...Microphone for the passenger seat, MNS...Mask noise sound source, SP_D...Speaker for the driver's seat, SP_P...Speaker for the passenger seat.

Claims

1. A first-seat speaker positioned near the first seat of the car, A microphone is positioned near the head of the user seated in the first seat, A second-seat speaker positioned near the second seat of the car, A sound source for the first seat that outputs the first audio signal, A mask noise sound source that outputs a predetermined noise signal as a mask noise signal, An audio signal processing device that synthesizes a first audio signal output by the first seat sound source and a mask noise signal output by the mask noise sound source and outputs the result to the first seat speaker, It has a second-seat sound source that outputs a second audio signal from the second-seat speaker, The aforementioned audio signal processing device is A crosstalk detection unit that extracts the component of the second audio signal included in the output of the microphone as a crosstalk signal, A noise detection unit extracts a component from the output of the microphone that does not include the component of the second audio signal or the component of the output sound of the first seat speaker, but includes a component of noise unrelated to the audio system, as a noise signal. A gain calculation unit calculates the gain adjustment amount for the mask noise signal such that the mask noise signal becomes larger by a predetermined amount than the difference in magnitude between the crosstalk signal and the noise signal. A gain adjustment unit adjusts the gain of the mask noise signal output by the mask noise sound source using the gain adjustment amount calculated by the gain calculation unit, An audio system characterized by having a gain adjustment unit that combines a mask noise signal with adjusted gain and a first audio signal output by the first seat sound source, and outputs the combined signal to the first seat speaker.

2. The audio system according to claim 1, The audio system is characterized in that the crosstalk detection unit generates the crosstalk signal by removing the noise signal component and the signal component output by the synthesis unit to the first seat speaker from the output of the microphone.

3. The audio system according to claim 1, The audio system is characterized in that the noise detection unit generates the noise signal by removing the components of the second audio signal and the components of the signal output by the synthesis unit to the first seat speaker from the output of the microphone.

4. The audio system according to claim 1, The crosstalk detection unit removes the noise signal component and the signal component output by the synthesis unit to the first seat speaker from the microphone output to generate the crosstalk signal. The audio system is characterized in that the noise detection unit generates the noise signal by removing the components of the second audio signal and the components of the signal output by the synthesis unit to the first seat speaker from the output of the microphone.

5. A first-seat speaker positioned near the first seat of the car, A second-seat speaker positioned near the second seat of the car, A sound source for the first seat that outputs the first audio signal, A mask noise sound source that outputs a predetermined noise signal as a mask noise signal, An audio signal processing device that synthesizes a first audio signal output by the first seat sound source and a mask noise signal output by the mask noise sound source and outputs the result to the first seat speaker, A second-seat sound source that outputs a second audio signal from the second-seat speaker, It has a sensor that detects the behavior of the vehicle, The aforementioned audio signal processing device is A crosstalk detection unit generates a crosstalk signal by convolving the second audio signal with a transfer function obtained in advance from the sound source for the second seat to the position of the user's head seated in the first seat, A noise detection unit generates a noise signal that represents noise determined according to the relationship between the behavior detected by the aforementioned sensor and noise unrelated to the audio system, which was determined in advance. A gain calculation unit calculates the gain adjustment amount for the mask noise signal such that the mask noise signal becomes larger by a predetermined amount than the difference in magnitude between the crosstalk signal and the noise signal. A gain adjustment unit adjusts the gain of the mask noise signal output by the mask noise sound source using the gain adjustment amount calculated by the gain calculation unit, An audio system characterized by having a gain adjustment unit that combines a mask noise signal with adjusted gain and a first audio signal output by the first seat sound source, and outputs the combined signal to the first seat speaker.

6. The audio system according to claim 5, The behavior detected by the sensor is the acceleration of the vehicle's vibration. The aforementioned noise is characterized by being road noise.

7. An audio system according to claim 1, 2, 3, 4, 5, or 6, The gain calculation unit calculates the gain adjustment amount for the mask noise signal for each predetermined bandwidth such that the mask noise signal becomes larger by a predetermined amount than the difference in magnitude between the crosstalk signal and the noise signal. The audio system is characterized in that the gain adjustment unit adjusts the gain of the mask noise signal output by the mask noise sound source for each of the bands by the gain adjustment amount calculated by the gain calculation unit for that band.

8. The audio system according to claim 7, The audio system is characterized in that the gain calculation unit calculates the gain adjustment amount for the mask noise signal for each of the bands such that the perceived loudness of the combined sound of the sound corresponding to the mask noise signal and the sound corresponding to the noise signal is perceived to be a predetermined level louder than the perceived loudness of the sound corresponding to the noise signal alone.

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