Audio system

Abstract

This audio system uses speakers located on either side of the seats and provides an audio system that achieves a good sense of localization in the forward position. [Solution] A_L_SPK and A_R_SPK are positioned on the left and right sides of the driver's seat headrest of the car, and B_L_SPK and B_R_SPK are positioned on the left and right sides of the passenger seat headrest of the car. Front speaker F_SPK is positioned above the rearview mirror of the car. A_L_SPK and A_R_SPK are output to the left and right channels of the first audio signal, respectively, and B_L_SPK and B_R_SPK are output to the left and right channels of the second audio signal, respectively. Front speaker F_SPK is output to extract components that correlate with each channel of the first audio signal and each channel of the second audio signal.

Description

Technical Field

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

Background Art

[0002] As a technology related to the present invention, there is known a technology for providing a localization feeling of sound images to a sound image localization target position by respectively convolving the acoustic transfer characteristics (head transfer function) from the sound image localization target position to each of the left and right ears of a listener with an audio signal to generate L and R channel audio signals and outputting them to left and right speakers (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] When applying the technology of outputting the L and R channel audio signals convolved with the head transfer functions to each of the left and right ears described above to an audio system using speakers provided on the left and right of a seat such as the left and right of a headrest, it is difficult to realize a good localization feeling to a position in front of the user without performing precise adjustment for each individual user because the speakers are located at the rear of the user's head, etc.

[0005] Therefore, an object of the present invention is to realize a good localization feeling to a position in front in an audio system using speakers provided on the left and right of a seat.

Means for Solving the Problems

[0006] To achieve the above objectives, the present invention provides an audio system comprising: a first left speaker positioned to the left of the head of a user seated in a first seat; a first right speaker positioned to the right of the head of a user seated in the first seat; a second left speaker positioned to the left of the head of a user seated in a second seat, which is a seat adjacent to the first seat; a second right speaker positioned to the right of the head of a user seated in the second seat; a front speaker positioned in front of the first and second seats, between the first and second seats in the left-right direction; and an acoustic signal processing device. Here, the audio signal processing device includes a seat speaker output means that outputs the left channel signal of a stereo 2-channel first audio signal to the 1 left speaker, outputs the right channel signal of the first audio signal to the 1 right speaker, outputs the left channel signal of a stereo 2-channel second audio signal which is the same as or different from the first audio signal to the 2 left speakers, and outputs the right channel signal of the second audio signal to the 2 right speakers; and a front seat speaker output means that extracts components correlated with all the signals of each channel of the left and right channels of the first audio signal and the left and right channels of the second audio signal, and outputs them as a front channel signal to the front speaker.

[0007] Here, the audio signal processing device generates an audio signal as the first audio signal, which is obtained by convolving the transfer function of a monaural 1-channel audio signal so that the head transfer function from the set sound image localization position to the left ear matches the transfer function to the left ear of the user seated in the first seat, and an audio signal as the right channel signal, which is obtained by convolving the transfer function of the 1-channel audio signal so that the head transfer function from the set sound image localization position to the right ear matches the transfer function to the right ear of the user seated in the first seat. Stereo audio signal generation means may be provided to generate a second audio signal, which is an audio signal obtained by convolving the transfer function of a single channel of stereo audio signal so that the head transfer function from the set sound image localization position to the left ear matches the transfer function to the left ear of a user seated in the second seat, and an audio signal obtained by convolving the transfer function of the single channel audio signal so that the head transfer function from the set sound image localization position to the right ear matches the transfer function to the right ear of a user seated in the second seat, as the second audio signal.

[0008] Furthermore, the audio system may be configured such that the acoustic signal processing device outputs the front channel signal to the front speaker only when the direction of the localization position of the target sound image is within a predetermined range centered on the front, and suppresses the output of the front channel signal to the front speaker when it is not within the predetermined range.

[0009] Furthermore, the audio system may be configured such that the sound signal processing device can be set to stereo audio signal generation means so that it can set different localization positions for the target sound image, one for the localization position of the target sound image used to generate the first audio signal, and the other for the localization position of the target sound image used to generate the second audio signal.

[0010] In the audio system described above, the first seat and the second seat may be seats arranged side by side in the automobile, and the first seat may be the driver's seat of the automobile, and the second seat may be the passenger seat of the automobile. According to the audio system described above, in an audio system that uses speakers located on the left and right of two seats arranged side by side, a signal that correlates with all the outputs of the speakers at each seat, output from a single front speaker positioned between the left and right in front of the two seats, can induce the perceived localization position of the users of the two seats to move forward, thereby achieving a good sense of localization of the position in front of the users of both seats. [Effects of the Invention]

[0011] As described above, according to the present invention, in an audio system using speakers provided on the left and right sides of the seat, a good sense of localization to the front position can be achieved. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows the configuration of an audio system according to an embodiment of the present invention. [Figure 2] This diagram shows the arrangement of speakers according to an embodiment of the present invention. [Figure 3] This figure shows the configuration of the head transfer function convolution section according to an embodiment of the present invention. [Figure 4] This figure shows the configuration of each correlation component extraction unit according to the embodiment of the present invention. [Figure 5] This figure shows the usage range of the front channel signal according to an embodiment of the present invention. [Figure 6] This figure shows another example configuration of an audio system according to an embodiment of the present invention. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below. Figure 1 shows the configuration of the audio system according to this embodiment. The audio system is a system installed in a car and, as shown in the figure, includes a sound source device 1 that outputs a 1-channel monaural audio signal Sin, an acoustic signal processing device 2, a left speaker A_L_SPK for seat A, a right speaker A_R_SPK for seat A, a left speaker B_L_SPK for seat B, a right speaker B_R_SPK for seat B, and a front speaker F_SPK.

[0014] Here, seat A represents one seat in a car, and seat B represents the seat adjacent to seat A to the left or right. In the following explanation, seat A will refer to the driver's seat of a car, and seat B will refer to the passenger seat. As shown in Figures 2a and 2b, the left speaker for seat A, A_L_SPK, is positioned to the left of the driver's seat headrest, the right speaker for seat A, A_R_SPK, is positioned to the right of the driver's seat headrest, the left speaker for seat B, B_L_SPK, is positioned to the left of the passenger seat headrest, and the right speaker for seat B, B_R_SPK, is positioned to the right of the passenger seat headrest.

[0015] However, the left speaker for seat A, A_L_SPK, may be located on the left side of the driver's seat backrest, the right speaker for seat A, A_R_SPK, may be located on the right side of the driver's seat backrest, the left speaker for seat B, B_L_SPK, may be located on the left side of the passenger seat backrest, and the right speaker for seat B, B_R_SPK, may be located on the right side of the passenger seat backrest.

[0016] Furthermore, as shown in Figure 2c, the front speaker F_SPK is positioned above the rearview mirror of the car. Returning to Figure 1, the acoustic signal processing device 2 comprises a signal processing unit 21 for seat A, a signal processing unit 22 for seat B, a unit 23 for extracting correlation components between both seats, and a localization control unit 24. The signal processing unit 21 for seat A and the signal processing unit 22 for seat B have the same configuration and perform the same operation. That is, the signal processing unit 21 for seat A and the signal processing unit 22 for seat B include a head-related transfer function convolution unit 201, a left-right correlation component extraction unit 202, a left-right balance adjustment unit 203, and a sound field control unit 204. The head-related transfer function convolution unit 201 convolves the audio signal Sin output from the sound source device 1 with the head-related transfer function for the left ear and the head-related transfer function for the right ear set by the localization control unit 24 respectively to generate a two-channel stereo signal, and outputs the L signal and the R signal of the stereo signal.

[0017] The left-right correlation component extraction unit 202 extracts and outputs the correlation component of the L signal and the R signal output by the head-related transfer function convolution unit 201. The left-right balance adjustment unit 203 adjusts the level balance between the L signal and the R signal output by the head-related transfer function convolution unit 201 according to the control of the localization control unit 24, and outputs the adjusted L signal and R signal. The sound field control unit 204 performs predetermined processing on the L signal and the R signal output by the left-right balance adjustment unit 203, and outputs the processed L signal and R signal to the corresponding speakers. The speaker corresponding to the L signal of the signal processing unit 21 for seat A is the left speaker A_L_SPK for seat A, the speaker corresponding to the R signal of the signal processing unit 21 for seat A is the right speaker A_R_SPK for seat A, the speaker corresponding to the L signal of the signal processing unit 22 for seat B is the left speaker B_L_SPK for seat B, and the speaker corresponding to the R signal of the signal processing unit 22 for seat B is the right speaker B_R_SPK for seat B.

[0018] Also, the sound field control unit 204 of the signal processing unit 21 for seat A performs cross-talk cancellation processing such as adding a sound signal that cancels the L signal output from the left speaker A_L_SPK for seat A at the position of the right ear of the user in seat A to the R signal output to the right speaker A_R_SPK for seat A, and adding a sound signal that cancels the R signal output from the right speaker A_R_SPK for seat A at the position of the left ear of the user in seat A to the L signal output to the left speaker A_L_SPK for seat A.

[0019] Similarly, the sound field control unit 204 of the B-seat signal processing unit 22 performs crosstalk cancellation processing, such as adding a sound signal that cancels the L signal output from the B-seat left speaker B_L_SPK at the position of the B-seat user's right ear to the R signal output to the B-seat right speaker B_R_SPK, and adding a sound signal that cancels the R signal output from the B-seat right speaker B_R_SPK at the position of the B-seat user's left ear to the L signal output to the B-seat left speaker B_L_SPK.

[0020] Next, the dual-seat correlation component extraction unit 23 extracts the correlation component between the output signal of the left-right correlation component extraction unit 202 of the A-seat signal processing unit 21 and the output signal of the left-right correlation component extraction unit 202 of the B-seat signal processing unit 22, and outputs it as an F signal to the front speaker F_SPK. The dual-seat correlation component extraction unit 23 also outputs / stops the F signal to the front speaker F_SPK according to the control of the localization control unit 24.

[0021] Next, Figure 3 shows the configuration of the head-of-seat transfer function convolution section 201 of the A-seat signal processing unit 21 and the B-seat signal processing unit 22. As shown in the figure, the head-to-head transfer function convolution section 201 comprises a left orbital head-to-head transfer function convolution section 2011 and a right orbital head-to-head transfer function convolution section 2012. The left ear-head transfer function convolution unit 2011 convolves the head-head transfer function for the left ear, set by the positioning control unit 24, into the audio signal Sin output by the sound source device 1 and outputs it as an L signal. The right ear-head transfer function convolution unit 2012 convolves the head-head transfer function for the right ear, set by the positioning control unit 24, into the audio signal Sin output by the sound source device 1 and outputs it as an R signal.

[0022] Next, the configuration of the left-right correlation component extraction unit 202 of the A-seat signal processing unit 21 and the B-seat signal processing unit 22, and the dual-seat correlation component extraction unit 23 will be described. As described above, the left-right correlation component extraction unit 202 of the A-seat signal processing unit 21 and the B-seat signal processing unit 22, and the two-seat correlation component extraction unit 23 are processing units that extract and output the correlation components of two input signals. As a configuration for such a processing unit that extracts the correlation components of two signals, the configuration of the correlation component extraction unit shown in Figure 4a can be used.

[0023] The correlation component extraction unit shown in Figure 4a extracts the correlation components of the two input signals S1 and S2 and outputs Sout. The correlation component extraction unit comprises a first correlation component extraction unit 401, a second correlation component extraction unit 402, and a correlation component addition unit 403. The first correlation component extraction unit 401 extracts and outputs a component C1 from the input signal S2 that correlates with the input signal S1, the second correlation component extraction unit 402 extracts and outputs a component C2 from the input signal S1 that correlates with the input signal S2, and the correlation component summing unit 403 adds the output C1 from the first correlation component extraction unit 401 and the output C2 from the second correlation component extraction unit 402 and outputs it as Sout.

[0024] Next, Figure 4b shows the configuration of the first correlation component extraction unit 401. As shown in the figure, the first correlation component extraction unit 401 includes a variable filter 4011, an update unit 4012 that updates the transfer function (filter coefficients) W of the variable filter 4011 using an adaptive algorithm such as the LMS algorithm, and an adder 4013. The variable filter 4011, the update unit 4012, and the adder 4013 constitute an adaptive filter.

[0025] The variable filter 4011 receives signal S1 as input, and the adder 4013 subtracts the output of the variable filter 4011 from signal S2 and outputs the result. The update unit 4012 uses the output of the adder 4013 as an error and executes an adaptive algorithm to update the transfer function W of the variable filter 4011 so that the power of the error is minimized.

[0026] The power of the adder 4013's output is minimized when the output of the variable filter 4011 matches component C1 of the signal S2 that correlates with signal S1. Therefore, a component C1 correlated with signal S1 in signal S2 can be extracted as the output of the variable filter 4011. Next, the configuration and operation of the second correlation component extraction unit 402 are the same as in the description of the first correlation component extraction unit 401 above, with S1 and S1 swapped. The following describes the control of the positioning control unit 24 in this configuration. The localization control unit 24 sets the target localization direction and target localization position of the sound image of the target audio signal Sin, according to prior settings or commands from an external source. The target position may be set as a predetermined distance from the target position to the user, depending on the target positioning direction set in advance or according to an external command. First, the positioning control unit 24 controls the output / stop of the F signal from the two-seat correlation component extraction unit 23 to the front speaker F_SPK according to the target positioning direction. In other words, the localization control unit 24, when the target localization direction is not within the forward range, stops outputting the F signal of the two-seat correlation component extraction unit 23 to the front speaker F_SPK, because it can provide a relatively good sense of localization to the target localization direction using only the speakers on the left and right of the headrests. Only when the target localization direction is within the forward range does the two-seat correlation component extraction unit 23 output the F signal to the front speaker F_SPK.

[0027] More specifically, as shown in Figure 5a, for example, assuming that the front is 0° and the measurement is taken counterclockwise up to 360°, the output of the F signal from the two-seat correlation component extraction unit 23 to the front speaker F_SPK is stopped when the target localization direction is in the range of 90° to 270°, and the two-seat correlation component extraction unit 23 is made to output the F signal to the front speaker F_SPK when the target localization direction is in the range of 0° to 90° and 270° to 360°, which are considered the front range.

[0028] Here, the range of target localization directions to be considered as the forward range, and the output of the F signal to the front speaker F_SPK by the two-seat correlation component extraction unit 23, can be determined on a case-by-case basis. For example, if the range of target localization directions in which a relatively good sense of localization to the target localization direction can be provided using only the left and right headrest speakers is from 75° to 295°, as shown in Figure 5b, then the range from 0° to 75° to 295° to 360° can be considered as the forward range, and the F signal can be output to the front speaker F_SPK only within the forward range.

[0029] Next, when the target localization direction is within the forward range, the localization control unit 24 sets the left ear head-head transfer function in the left ear head-head transfer function convolution unit 2011 of the seat A signal processing unit 21 so that the head-head transfer function from the target localization position to the left ear of the user in seat A becomes a transfer function corresponding to the target localization position, and sets the right ear head-head transfer function in the right ear head-head transfer function convolution unit 2012 of the seat A signal processing unit 21 so that the head-head transfer function from the target localization position to the right ear of the user in seat A becomes a transfer function corresponding to the target localization position.

[0030] Similarly, when the target localization direction is in the forward range, the localization control unit 24 sets the left ear head-to-head transfer function in the left ear head-to-head transfer function convolution unit 2011 of the B-seat signal processing unit 22 so that the head-to-head transfer function from the target localization position to the left ear of the user in seat B becomes a transfer function corresponding to the target localization position, and sets the right ear head-to-head transfer function in the right ear head-to-head transfer function convolution unit 2012 of the B-seat signal processing unit 22 so that the head-to-head transfer function from the target localization position to the right ear of the user in seat B becomes a transfer function corresponding to the target localization position.

[0031] Furthermore, the positioning control unit 24 also performs a process in which the left-right balance adjustment unit 203 of the A-seat signal processing unit 21 and the B-seat signal processing unit 22 adjusts the level balance between the L signal and the R signal so that the sense of localization in the target localization direction is enhanced according to the target localization direction. Embodiments of the present invention have been described above. According to this embodiment, in an audio system using speakers located on the left and right sides of two seats arranged side by side, a signal correlated with all the outputs of the speakers at each seat, output from a single front speaker F_SPK positioned between the left and right sides in front of the two seats, can induce the perceived localization position of the users of the two seats to move forward, thereby achieving a good sense of localization of the position in front of the users of both seats.

[0032] By the way, in the above, the localization control unit 24 set a common target localization position and target localization direction for the user in seat A and the user in seat B. However, if different target localization positions and target localization directions are set for the user in seat A and the user in seat B, the head-to-head transfer function convolution units 201 of the signal processing unit 21 for seat A and the signal processing unit 22 for seat B are set with left ear-to-head transfer functions and right ear-to-head transfer functions according to the set target localization position and target localization direction, respectively.

[0033] Furthermore, in this case, the two-seat correlation component extraction unit 23 outputs the F signal to the front speaker F_SPK only when both the target localization direction of the user in seat A and the user in seat B are within the forward range. Furthermore, although the front speaker F_SPK was positioned above the rearview mirror in the above description, it can be placed in any other position in front of the front seats of the car, between the driver's seat and the passenger seat, such as the center of the dashboard shown in Figure 6a. Furthermore, as shown in Figure 6b, the above embodiment can be applied to the right rear seat and the left rear seat of a car, designated as seat A and seat B. In this case, the front speaker F_SPK can be positioned in the center of the ceiling in the left-right direction in front of the rear seats. [Explanation of Symbols]

[0034] 1...Sound source device, 2...Acoustic signal processing device, 21...Seat A signal processing unit, 22...Seat B signal processing unit, 23...Both seat correlation component extraction unit, 24...Sound localization control unit, 201...Head-to-head transfer function convolution unit, 202...Left-to-right correlation component extraction unit, 203...Left-to-right balance adjustment unit, 204...Sound field control unit, 401...First correlation component extraction unit, 402...Second correlation component extraction unit, 403...Correlation component addition unit, 2011...Left ear-head transfer function convolution unit, 2012...Right ear-head transfer function convolution unit, 4011...Variable filter, 4012...Update unit, 4013...Adder.

Claims

1. A first left speaker is positioned to the left of the head of the user seated in the first seat, A first right speaker is positioned on the first seat at a location to the right of the head of the user seated in that seat, A second left speaker is positioned to the left of the head of a user seated in a second seat, which is a seat located to the left of the first seat, A second right speaker is positioned on the second seat at a location to the right of the head of the user seated in that seat, A front speaker positioned in front of the first and second seats, between the first and second seats in the left-right direction, It has an acoustic signal processing device, The sound signal processing device includes a seat speaker output means that outputs the left channel signal of a stereo two-channel first audio signal to the left speaker 1, the right channel signal of the first audio signal to the right speaker 1, the left channel signal of a stereo two-channel second audio signal which is the same as or different from the first audio signal to the left speakers 2, and the right channel signal of the second audio signal to the right speakers 2. An audio system characterized by having a front speaker output means that extracts components correlated with all the signals of the left and right channels of the first audio signal and the left and right channels of the second audio signal, and outputs them to the front speakers as a front channel signal.

2. The audio system according to claim 1, The aforementioned acoustic signal processing device is An audio signal is generated as the first audio signal, which is obtained by convolving a mono 1-channel audio signal with a transfer function such that the head transfer function from the set sound image localization position to the left ear matches the transfer function from the user seated in the first seat to the left ear, and the right channel audio signal is obtained by convolving the 1-channel audio signal with a transfer function such that the head transfer function from the set sound image localization position to the right ear matches the transfer function from the user seated in the first seat to the right ear, and so on. An audio system characterized by having a stereo audio signal generation means that generates a second audio signal, which is obtained by convolving the transfer function of the mono 1-channel audio signal so that the head transfer function from the set sound image localization position to the left ear matches the transfer function to the left ear of a user seated in a second seat, and the right channel audio signal is obtained by convolving the transfer function of the 1-channel audio signal so that the head transfer function from the set sound image localization position to the right ear matches the transfer function to the right ear of a user seated in a second seat, and the second audio signal is obtained by convolving the transfer function of the 1-channel audio signal so that the head transfer function from the set sound image localization position to the right ear matches the transfer function to the right ear of a user seated in a second seat.

3. The audio system according to claim 2, The audio system is characterized in that the acoustic signal processing device outputs the front channel signal to the front speaker only when the direction of the localization position of the target sound image is within a predetermined range centered on the front, and suppresses the output of the front channel signal to the front speaker when it is not within the predetermined range.

4. The audio system according to claim 2, The audio system is characterized in that the sound signal processing device has a stereo audio signal generation means capable of setting different localization positions for the target sound image, one for use in generating the first audio signal and the other for use in generating the second audio signal.

5. An audio system according to claim 1, 2, 3, or 4, An audio system characterized in that the first and second seats are seats arranged side by side on the left and right sides of the automobile.

6. An audio system according to claim 1, 2, 3, or 4, An audio system characterized in that the first seat is the driver's seat of an automobile, and the second seat is the passenger seat of the automobile.

Images