Sound system

Abstract

The present invention addresses the problem of providing a sound system that outputs a notification sound that is easy to listen to by a specific user within a range that does not cause trouble to other users. [Solution] A notification sound output from a notification sound source (1) is output to a driver from a speaker (3) disposed on a headrest of a driver's seat after the gain of the notification sound is adjusted by a variable gain amplifier (2). A gain setting unit (5) estimates the power of noise at each seat on the basis of the sound received by the microphone (4), and determines the power of noise at each seat by using a transfer function (Cd) for the notification sound from the speaker (3) to the user of the driver's seat and a transfer function (Ct) for the notification sound from the speaker (3) to the user of the specific seat, said transfer functions being obtained in advance. The gain of the notification sound is calculated such that the notification sound is larger than the noise at the driver's seat and smaller than the noise at the specific seat, and is set to the variable gain amplifier (2).

Description

Technical Field

[0001] The present invention relates to a technology for outputting sound to a specific user in a manner that does not cause trouble to other users. Background Art

[0002] As a technique for outputting sound to a specific user without causing trouble to other users, there is known a technique in which a speaker is provided on a headrest of a car seat and the speaker outputs sound to the user sitting in the seat (for example, Patent Document 1).

[0003] Prior art literature:

[0004] Patent Literature:

[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-95646 Summary of the invention

[0006] Problems to be solved by the invention:

[0007] Even when a speaker provided at a headrest of a seat of a car outputs sound to a user sitting in the seat, if the volume is high, other users may hear the sound output from the speaker and cause trouble. On the other hand, if the volume is reduced to a level that other users cannot hear, it is difficult for the user sitting in the seat to hear the sound output from the speaker.

[0008] Therefore, an object of the present invention is to output, to a specific user, a sound that the specific user can easily hear without causing trouble to other users.

[0009] Means used to solve the problem:

[0010] In order to achieve the above-mentioned problem, the present invention is an audio system for outputting sound output from a sound source as notification sound to a user sitting in a first seat among a plurality of seats arranged indoors, the system comprising: a speaker arranged at a position closest to a user sitting in the first seat among the users seated in the seats; a gain adjustment mechanism for adjusting the level of the sound output from the sound source with a set gain and outputting the sound as the notification sound to the speaker; a gain setting mechanism for pre-setting a first transfer function and a second transfer function, the gain being set to the gain adjustment mechanism, the first transfer function being a transfer function of the notification sound from the speaker to the user sitting in the first seat, and the second transfer function being a transfer function of the notification sound from the speaker to the user sitting in a second seat, the second seat being a seat different from the first seat among the plurality of seats; and a microphone for collecting noise in the room. Here, the gain setting mechanism infers the size of noise at each seat based on the noise picked up by the microphone, and based on the inferred noise size, the first transfer function and the second transfer function, calculates the gain of the notification sound so that the notification sound is louder than the noise at the position of the user sitting in the first seat and smaller than the noise at the position of the user sitting in the second seat, and sets the gain to the gain adjustment mechanism.

[0011] Here, the sound system may be configured such that, in the gain setting means, when the power of the noise at each seat estimated is set to P N The power of the signal obtained by convolving the sound output from the sound source with the first transfer function is set to P X , let the first transfer function be C d , let the second transfer function be C t , and the gain set to the gain adjustment mechanism is set to A, the gain set to the gain adjustment mechanism is calculated in a manner that satisfies the following formula:

[0012] A=α(P N / P X )

[0013] 1<α<C d / C t .

[0014] Furthermore, in the above audio system, the indoor area may be a vehicle cabin.

[0015] In order to achieve the above-mentioned problem, the present invention provides an audio system for outputting a sound output from a sound source as a notification sound to a user sitting in a first seat among a plurality of seats arranged in a vehicle cabin, the system comprising: a speaker arranged at a position closest to a user sitting in the first seat among the users sitting in the seats; a gain adjustment mechanism for adjusting the level of the sound output from the sound source with a set gain and outputting the sound as the notification sound to the speaker; a gain setting mechanism for presetting a first transfer function and a second transfer function, the gain being set to the gain adjustment mechanism, the first transfer function being a transfer function of the notification sound from the speaker to the user sitting in the first seat, and the second transfer function being a transfer function of the notification sound from the speaker to the user sitting in a second seat among the plurality of seats different from the first seat; and a microphone for collecting noise in the vehicle cabin. Here, the gain setting mechanism estimates the magnitude of the noise at each seat based on the noise collected by the microphone, and sets the power of the estimated noise at each seat as P. N The power of a signal obtained by convolving the signal obtained by adjusting the level of the sound output from the sound source by the gain adjustment mechanism with the set gain and the first transfer function is set to P XA The power of a signal obtained by convolving the signal obtained by adjusting the level of the sound output from the sound source by the gain adjustment mechanism with the set gain and the second transfer function is set to P XA , the gain set to the gain adjustment mechanism is calculated in a manner that satisfies the following formula as much as possible:

[0016] -0.41P N +34.71<P XA / P N <-0.71P N +57.03,

[0017] and,

[0018] P TA / P N <-0.41P N +34.71.

[0019] Here, in the above-mentioned audio system in which the interior is a vehicle cabin, the first seat may be a driver's seat of the vehicle.

[0020] In addition, in this case, the speaker is preferably provided on a headrest of the driver's seat.

[0021] In addition, in this case, the second seat can be set as a seat among the seats of the car other than the driver's seat, in which the gain of the transfer function of the notification sound from the speaker to the user sitting in the seat is the largest, or it can be set as a seat selected by the user from among the seats of the car other than the driver's seat.

[0022] According to the above-described audio system, the notification sound can be outputted so that the user at the first seat hears the notification sound at a level that is not buried by noise, and the user at the second seat cannot clearly hear the notification sound because it is blocked by noise.

[0023] Effect of the invention:

[0024] As described above, according to the present invention, it is possible to output a sound that is easy for a specific user to hear, to a specific user, within a range that does not cause trouble to other users. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a block diagram showing the configuration of an acoustic system according to an embodiment of the present invention.

[0026] Figure 2 It is a diagram showing the arrangement of microphones and speakers in an audio system according to an embodiment of the present invention.

[0027] Figure 3 It is a diagram showing a transfer function considered in the acoustic system according to the embodiment of the present invention.

[0028] Figure 4 It is a diagram showing an example of volume control of the acoustic system according to the embodiment of the present invention.

[0029] Description of reference numerals:

[0030] 1...notification sound source, 2...variable gain amplifier, 3...speaker, 4...microphone, 5...gain setting unit, 6...control unit. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present invention will be described.

[0032] Figure 1 The configuration of an acoustic system according to this embodiment is shown.

[0033] The audio system is a system installed in a car, and as shown in the figure, includes a notification sound source 1 for outputting a notification sound, a variable gain amplifier 2 with a variable gain A, a speaker 3, a microphone 4, a gain setting unit 5, and a control unit 6.

[0034] The notification sound output by the notification sound source 1 is, for example, a message voice or warning sound of a car navigation system, or a sound expressing driving information for the driver.

[0035] The notification sound outputted from the notification sound source 1 is outputted from the speaker 3 after its power is adjusted by the variable gain amplifier 2. The gain A of the variable gain amplifier 2 is set by the gain setting unit 5.

[0036] Next, if Figure 2 As shown in a and b of FIG. 1 , the speaker 3 is disposed on the headrest of the driver's seat and is configured to output a notification sound to the driver sitting in the driver's seat.

[0037] The microphone 4 collects noise in the vehicle, such as engine noise and road noise. The microphone 4 can be disposed, for example, at a central position in the vehicle on the ceiling.

[0038] Next, setting of the gain A of the variable gain amplifier 2 by the gain setting unit 5 will be described.

[0039] In this setting, a transfer function of the target frequency domain from the speaker 3 to the user sitting in each seat is used.

[0040] The target frequency domain is the frequency domain of the notification sound, and is set to 100 Hz to 1 kHz, which is the frequency domain of human voice, for example.

[0041] The following, such as Figure 3 As shown, use C d The transfer function of the target frequency domain from the speaker 3 arranged on the headrest of the driver's seat to the user (driver) sitting in the driver's seat is expressed, i is the seat number of each seat other than the driver's seat, and C i (C1 to C6 in the figure) represent the transfer function of the target frequency domain from the speaker 3 to the user sitting in each seat other than the driver's seat. Here, the speaker 3 is arranged on the headrest of the driver's seat, so the transfer function C of the driver's seat is d The gain transfer function with other seats C i The gain is significantly larger than that of .

[0042] return Figure 1 , the transfer function C to the user sitting in each seat is obtained in advance by actual measurement for each vehicle type. d , transfer function C i , and stored in the control unit 6.

[0043] The control unit 6 sets the transfer function C of the driver's seat to the gain setting unit 5. d , and sets the transfer function corresponding to a specific seat among the seats other than the driver's seat to the gain setting unit 5 as the target transfer function C t .

[0044] Here, for convenience, the target transfer function C set to the gain setting unit 5 is t The corresponding seat is referred to as a "target seat" for explanation.

[0045] As the target transfer function C t , set the transfer function C i A transfer function with the largest gain among the seats, or a transfer function corresponding to a seat (e.g., a VIP seat) set by the user as a target seat among the seats other than the driver's seat.

[0046] Here, as the target transfer function C t , or the transfer function C can be fixed i In this case, only the transfer function C of the driver's seat can be d , and the transfer function C i The setting is the target transfer function C t The transfer function C of the driver's seat may be stored in advance in the control unit 6. Alternatively, the transfer function C of the driver's seat may not be stored in the control unit 6. d Or the transfer function C i , and the transfer function C of the driver's seat d And set as the target transfer function C t The transfer function is pre-set to the gain setting unit 5.

[0047] The transfer function C of the driver's seat is set d and the target transfer function C t The gain setting unit 5 calculates the power P of the target frequency domain of the noise in the vehicle collected by the microphone 4. N Here, the level of the in-vehicle noise, such as engine noise or road noise, is uniformly the same in the vehicle, so the power P obtained from the noise picked up by the microphone 4 is N It can be used to express the power of noise at each seat in the car.

[0048] Then, the gain setting unit 5 adjusts the noise power P N , the notification sound input from the notification sound source 1, the transfer function C of the set driver's seat d , and the target transfer function C t , the gain A is calculated by the following formula and set to the variable gain amplifier 2.

[0049] A=α(P N / P X )

[0050] 1<α<C d / C t

[0051] Among them, P X is the transfer function C between the notification sound input from notification sound source 1 (without gain adjustment) and the driver's seat d The power of the signal obtained by convolution.

[0052] Here, when α = 1,

[0053] Become A=P N / P X , the power of the notification sound transmitted to the user in the driver's seat A·P X become:

[0054] A.P. X =(P N / P X )·P X =P N , so the SNR of the notification sound at the driver's seat relative to the noise becomes 0dB.

[0055] On the other hand, when α=C d / C t hour,

[0056] Become A=(C d / C t )·(P N / P X ), the power C of the notification sound delivered to the user in the target seat t ·A·(P X / C d )become:

[0057] C t ·A·(P X / C d )=C t ·(C d / C t )·(P N / P X )·(P X / C d )=(C t ·C d ·P N ·P X ) / (C t ·P X ·C d )

[0058] =P N , so the SNR of the notification sound at the target seat relative to the noise becomes 0dB.

[0059] Therefore, to satisfy 1<α<C d / C tThe gain A is calculated and set in a manner consistent with the conditions, so that the volume of the notification sound can be adjusted and output from the speaker 3 so that the notification sound is louder than the noise at the driver's seat and smaller than the noise at the target seat.

[0060] Therefore, the user in the driver's seat can hear the notification sound that is not buried by the noise, but the user in the target seat cannot hear the notification sound clearly because it is blocked by the noise.

[0061] Here, the gain A can be either d / C t The maximum value can be set within the range of the conditions of 1<α<C d / C t The gain is set to the closest pre-set standard gain within the range of conditions.

[0062] In addition, as the target transfer function C t The transfer function C is set i In the case of the transfer function with the largest gain, the notification sound is transmitted to the target seat to the maximum extent among the seats other than the driver's seat. Therefore, by calculating and setting the gain A as described above, the notification sound is smaller than the noise in all seats other than the driver's seat.

[0063] The gain A may be set in the gain setting unit 5 as follows.

[0064] In the ITU recommendation "Recommendation ITU-T P.1150, In-car communication audio specification", it is shown that the SNR between Upper (upper limit) y and Lower (lower limit) y in the following formula is the SNR of the sound preferably relative to the noise level x.

[0065] Upper; y = -0.71x + 57.03

[0066] Lower; y = -0.41x + 34.71

[0067] Therefore, when the signal after the notification sound is adjusted by gain A is compared with the transfer function C of the driver's seat d The power of the signal obtained by convolution is set to P XA , the SNR of the notification sound from the driver's seat is expressed as P XA / P N , the signal after the notification sound is adjusted by gain A and the target transfer function C t The power of the signal obtained by convolution is set to P TA , and the SNR of the notification sound of the target seat is expressed as P TA / PN When

[0068] -0.41P N +34.71<P XA / P N <-0.71P N +57.03

[0069] The SNR of the notification sound at the driver's seat becomes between Upper and Lower, allowing the user in the driver's seat to hear the notification sound with a preferred SNR.

[0070] On the other hand, if

[0071] P TA / P N <-0.41P N +34.71

[0072] Then, the SNR of the notification sound at the target seat is less than Lower, and the notification sound is masked by the noise and cannot be heard clearly.

[0073] Therefore, to satisfy -0.41P N +34.71<P XA / P N <-0.71P N +57.03 and P TA / P N <-0.41P N +34.71, calculate and set the gain A.

[0074] That is, for example, in Figure 4 As shown in the figure, when the median of Upper and Lower determined for the noise level is set as Target, the SNR of the driver's seat becomes the power P for the noise. N The gain A obtained by the Target method is determined if it satisfies P TA / P N <-0.41P N +34.71, the gain A calculated so that the SNR of the driver's seat becomes the Target is set to the variable gain amplifier 2.

[0075] Figure 4 The black dots represent the SNR of the driver's seat based on the gain A set in this way, and the diamonds represent the SNR of the target seat based on the gain A. As shown in the figure, under different noise levels such as when idling or traveling at 60 km / h, the user in the driver's seat can hear the notification sound at a preferred SNR, and the notification sound is masked by the noise and cannot be clearly heard at the target seat.

[0076] On the other hand, if the gain A obtained to become the Target does not satisfy P TA / P N <-0.41P N +34.71, find the value that satisfies -0.41P N +34.71<P XA / P N And P TA / P N <-0.41P N The maximum gain A of +34.71 is set for variable gain amplifier 2.

[0077] In addition, in the absence of -0.41P N +34.71<P XA / P N And P TA / P N <-0.41P N In the case of a gain A of +34.71, M is set to the specified margin, and the value that satisfies -0.41P is obtained. N +34.71+M=P XA / P N The gain A is set to variable gain amplifier 2.

[0078] The embodiments of the present invention have been described above.

[0079] Here, in the above embodiment, the speaker 3 is provided on the headrest of the driver's seat, but the speaker 3 may be provided at another position closest to the user sitting in the driver's seat among the users sitting in the seats.

[0080] In addition, the above embodiment represents a situation in which control is performed so that the user sitting in the driver's seat can hear the notification sound while the users sitting in other seats cannot clearly hear the notification sound, but the same can also be applied to a situation in which control is performed so that the user sitting in a specific seat other than the driver's seat can hear the notification sound while the users sitting in seats other than the specific seat cannot clearly hear the notification sound by replacing the relationship between the driver's seat and the specific seat in the above description.

[0081] In addition, the above embodiment describes the application to a car cabin, but the present embodiment can also be applied to any room in which a plurality of seats are fixedly arranged, so that users sitting in specific seats in the room can hear the notification sound, while users sitting in other seats cannot clearly hear the notification sound.

Claims

1. An audio system that outputs a sound output from a sound source as a notification sound to a user sitting at a first seat among a plurality of seats arranged indoors, characterized in that: have: a speaker arranged at a position closest to a user seated at the first seat among the users seated at the seats; a gain adjustment mechanism that adjusts the level of the sound output from the sound source with a set gain and outputs the sound to the speaker as the notification sound; a gain setting unit that is pre-set with a first transfer function and a second transfer function, and sets the gain to the gain adjustment unit, the first transfer function being a transfer function of the notification sound from the speaker to the user sitting at the first seat, and the second transfer function being a transfer function of the notification sound from the speaker to the user sitting at a second seat that is a seat different from the first seat among the plurality of seats; as well as A microphone is used to collect noise in the room. The gain setting mechanism infers the size of noise at each seat based on the noise picked up by the microphone, and calculates the gain of the notification sound so that the notification sound is louder than the noise at the position of the user sitting in the first seat and smaller than the noise at the position of the user sitting in the second seat based on the inferred noise size, the first transfer function and the second transfer function, and sets the gain to the gain adjustment mechanism.

2. The sound system according to claim 1, characterized in that The power of the noise at each seat is assumed to be P N The power of the signal obtained by convolving the sound output from the sound source with the first transfer function is set to P X , let the first transfer function be C d , let the second transfer function be C t , and the gain set to the gain adjustment mechanism is set to A, The gain setting mechanism calculates the gain set to the gain adjustment mechanism in a manner that satisfies the following formula: A9α(P N / P X ) 1<α<C d / C t 。 3. An audio system that outputs a sound output from a sound source as a notification sound to a user sitting in a first seat among a plurality of seats arranged in a vehicle cabin, characterized in that: have: a speaker arranged at a position closest to a user seated at the first seat among the users seated at the seats; a gain adjustment mechanism that adjusts the level of the sound output from the sound source with a set gain and outputs the sound to the speaker as the notification sound; a gain setting unit that is pre-set with a first transfer function and a second transfer function, and sets the gain to the gain adjustment unit, the first transfer function being a transfer function of the notification sound from the speaker to the user sitting at the first seat, and the second transfer function being a transfer function of the notification sound from the speaker to the user sitting at a second seat that is a seat different from the first seat among the plurality of seats; as well as A microphone is used to collect noise in the vehicle compartment. The gain setting mechanism estimates the magnitude of the noise at each seat based on the noise picked up by the microphone, and sets the power of the noise at each seat estimated to be P N The power of a signal obtained by convolving the signal obtained by adjusting the level of the sound output from the sound source by the gain adjustment mechanism with the set gain and the first transfer function is set to P XA The power of a signal obtained by convolving the signal obtained by adjusting the level of the sound output from the sound source by the gain adjustment mechanism with the set gain and the second transfer function is set to P XA , the gain set to the gain adjustment mechanism is calculated in a manner that satisfies the following formula as much as possible: -0.41P N +34.71<P XA / P N <-0.71P N +57.03, and, P TA / P N <-0.41P N +34.71。 4. The sound system according to claim 1, wherein: The interior is the compartment of the car.

5. The sound system according to claim 2, characterized in that The interior is the compartment of the car.

6. The sound system according to any one of claims 3 to 5, characterized in that: The first seat is the driver's seat of the car.

7. The sound system according to claim 6, characterized in that The speaker is arranged on the headrest of the driver's seat.

8. The sound system according to claim 6, characterized in that The second seat is a seat other than the driver's seat of the car, and is a seat having the largest gain in a transfer function of the notification sound from the speaker to a user sitting in the seat.

9. The sound system according to claim 6, characterized in that The second seat is a seat selected by the user from among seats of the car other than the driver's seat.

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