Intercommunication support system in vehicle

Abstract

The present invention provides an in-vehicle communication support system which eliminates unwanted sound and relays speech sound. A transfer function of a first variable filter (71) is updated to output an elimination sound (C) which minimizes a level of a signal obtained by subtracting an output of an auxiliary filter (75) for generating a correction signal which corrects a difference between the first seat microphone and a position of the first seat from an output (M) of the first seat microphone (5). A selector (6) inputs, as an input of the first variable filter (71), speech sound (Dp) output from the second seat speaker in an ICC mode in which the speech sound of the user of the first seat is output from the second seat speaker (4), and inputs, as an input of the first variable filter, an output sound (A2) of the second seat audio source (2) output from the second seat speaker in a non-ICC mode. The speech sound (Dp) is generated by removing a component of the elimination sound (C) from the output (M) of the first seat microphone (5).

Description

Technical Field

[0001] The present invention relates to a technology for supporting communication based on speech in a vehicle. Background Art

[0002] As a technology for supporting communication based on speech in a car, there is known a technology in which the speech of a user sitting in a first seat of the car is collected by a first-seat microphone and output from a speaker in a second seat of the car (for example, Patent Document 1).

[0003] In this type of technology, there is also known a technology that cancels the sound such as music output from the speaker for the first seat from the sound picked up by the microphone for the first seat and then outputs the sound from the speaker for the second seat (for example, Patent Document 2).

[0004] In addition, as a technology related to the present invention, the following active noise control (ANC) technology is known: a microphone is arranged near a noise cancellation position, an adaptive filter generates a cancellation sound for canceling noise at the noise cancellation position from an output signal of a noise source, and a speaker outputs the cancellation sound. In the adaptive filter, a signal obtained by correcting the output of the microphone using an auxiliary filter is used as an error signal, and a transfer function is adaptively set (for example, patent documents 3 and 4).

[0005] Here, in this technology, a pre-learned transfer function is set in the auxiliary filter. This transfer function corrects the signal actually output by the microphone to the signal output from the microphone when the microphone is configured at the noise cancellation position. By using such an auxiliary filter, noise is canceled at a noise cancellation position different from the position of the microphone.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-51392

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2010-163054

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2020-12917

[0011] Patent Document 4: Japanese Patent Application Laid-Open No. 2018-72770 Summary of the Invention

[0012] In order to support speech-based communication in the car, when the speech of a user sitting in the first seat of the car is collected by the microphone for the first seat and output from the speaker for the second seat of the car, the speech output from the speaker for the second seat is again collected by the microphone for the first seat, causing howling, or causing the user sitting in the first seat to feel uncomfortable when hearing the delayed speech of his or her own speech.

[0013] Furthermore, when the user at the first seat and the user at the second seat are listening to sounds from different sound sources, each user wishes not to hear the sound from the sound source being listened to by the other user.

[0014] Therefore, the object of the present invention is to suppress the ability of users to hear the sounds of the sound sources being listened to by other users in an environment where users in different seats of a car listen to sounds from different sound sources, and to suppress the ability of the microphone for the first seat of the car to pick up the speech sound that is picked up by the microphone for the first seat and output from the speaker for the second seat to pick up the speech sound.

[0015] To achieve the above-mentioned object, the present invention provides an in-vehicle communication support system installed in a vehicle having different seats, namely, a first seat and a second seat, and includes: a second-seat sound source device for the second seat; a second-seat speaker for a user in the second seat, which outputs the output sound of the second-seat sound source device; a microphone for collecting sound from the first seat; a noise control unit, which outputs a cancellation sound and a speech sound signal; a first-seat speaker for the user in the first seat, which outputs the cancellation sound output by the noise control unit; a selector, which selectively outputs one of the output sound of the second-seat sound source device and the speech sound signal output by the noise control unit as a reference sound to the noise control unit; and a control unit. The noise control unit includes: an error signal generator, which uses the output of the microphone to generate an error signal including a component of the reference sound in the microphone output; a first adaptive filter, which receives the reference sound as input and performs an adaptive operation to update a transfer function to reduce the magnitude of the error signal to generate the cancellation sound; and a speech sound signal generator, which generates a signal including a component of the speech sound of the user in the first seat in the microphone output as the speech sound signal. In addition, the in-vehicle communication support system has two operation modes, a first operation mode and a second operation mode. The first operation mode is an operation mode in which the speech sound signal output by the noise control unit is not output from the second-seat speaker, and the second operation mode is an operation mode in which the speech sound signal output by the noise control unit is output from the second-seat speaker. In the first operation mode, the control unit causes the selector to use the output sound of the second-seat sound source device as a reference sound and output it to the noise control unit. In the second operation mode, the control unit causes the selector to use the speech sound signal output by the noise control unit as a reference sound and output it to the noise control unit.

[0016] Here, in such an in-vehicle communication support system, it is also preferable that the speech sound signal generating unit generates a signal obtained by removing the canceling sound component from the output of the microphone as the speech sound signal.

[0017] In this case, the speech sound signal generating unit may generate the speech sound signal by subtracting a signal obtained by applying a transfer function of a transmission path to the microphone to the cancelling sound from the output of the microphone.

[0018] According to this in-vehicle communication support system, in the second operating mode, the speech of the user in the first seat can be output from the second seat speaker, thereby supporting communication between the user in the first seat and the user in the second seat based on the speech. Furthermore, using the same noise control unit, in the first operating mode in which the speech of the user in the first seat is not output from the second seat speaker, the output sound of the second seat sound source device output from the second seat speaker can be canceled for the user in the first seat. Furthermore, in the second operating mode in which the speech of the user in the first seat is output from the second seat speaker, the speech of the user in the first seat output from the second seat speaker can be canceled for the user in the first seat.

[0019] In the above-described in-vehicle communication support system, the noise control unit may be provided with an auxiliary filter that receives the reference sound as input, and the error signal generation unit may generate a signal obtained by subtracting at least the output of the auxiliary filter from the output of the microphone as the error signal. By subtracting the output of the auxiliary filter from the output of the microphone, a previously determined transfer function is set for the auxiliary filter, the transfer function being a transfer function that corrects the sound picked up by the microphone to the sound picked up at the listening position of the user in the first seat.

[0020] In addition, in the above-mentioned in-vehicle communication support system, it can also be configured so that a sound source device for the first seat, that is, a first-seat sound source device, which outputs output sound from the first-seat speaker is provided, and a second adaptive filter is provided in the noise control unit. The second adaptive filter takes the output sound of the first sound source device as input, performs an adaptive action of updating the transfer function to reduce the size of the error signal, and outputs a first-seat sound source cancellation sound. In the error signal generating unit, a signal obtained by subtracting at least the first-seat sound source cancellation sound from the output of the microphone is generated as the error signal.

[0021] In this way, the component of the output sound of the first sound source device output from the speaker for the first seat can be removed from the error signal used by the first adaptive filter in the adaptive operation. Therefore, it can be expected that the first variable filter can generate a cancellation sound for more appropriately canceling the output of the speaker for the second seat relative to the first seat.

[0022] In addition, the above-mentioned in-vehicle communication support system can also be provided with: a fixed filter, which takes the output sound of the second-seat sound source device as input and outputs the second-seat sound source cancellation sound; and an adding unit, which adds the second-seat sound source cancellation sound to the cancellation sound and outputs the result from the first-seat speaker, and in the control unit, in the first operation mode, the adding unit is not caused to add the second-seat sound source cancellation sound to the cancellation sound, and in the second operation mode, the adding unit is caused to add the second-seat sound source cancellation sound to the cancellation sound.

[0023] Here, in this case, in the in-vehicle communication support system, the control unit may be configured to set the transfer function of the first adaptive filter before switching as the transfer function of the fixed filter when the operation mode is switched from the first operation mode to the second operation mode.

[0024] Thus, even in the second operation mode, the output sound of the second-seat sound source device output from the second-seat speaker can be canceled relative to the first seat.

[0025] Effects of the Invention

[0026] As described above, according to the present invention, in an environment where users in different seats of a car are listening to sounds from different sound sources, it is possible to prevent users from hearing the sounds of the sound sources that other users are listening to, and it is possible to prevent the speech sound that is picked up by the microphone for the first seat of the car and output from the speaker for the second seat from being picked up again by the microphone for the first seat. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a block diagram showing the configuration of the in-vehicle communication support system according to the first embodiment of the present invention.

[0028] Figure 2 It is a diagram showing the arrangement of speakers and a first-seat microphone in the in-vehicle communication support system according to the first embodiment of the present invention.

[0029] Figure 3 This is a block diagram showing the configuration of an active noise control device according to the first embodiment of the present invention.

[0030] Figure 4 This is a flowchart showing the mode switching process according to the first embodiment of the present invention.

[0031] Figure 5 This is a block diagram showing a configuration for learning a transfer function of an auxiliary filter according to the first embodiment of the present invention.

[0032] Figure 6This is a block diagram showing the configuration of an in-vehicle communication support system according to a second embodiment of the present invention.

[0033] Figure 7 This is a block diagram showing the configuration of an active noise control device according to a second embodiment of the present invention.

[0034] Figure 8 This is a flowchart showing the mode switching process according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described.

[0036] First, a first embodiment will be described.

[0037] Figure 1 The configuration of the in-vehicle communication support system according to this embodiment is shown.

[0038] The in-vehicle communication support system is a system installed in a vehicle. As shown in the figure, it includes a first-seat audio source 1, a second-seat audio source 2, a first-seat speaker 3, a second-seat speaker 4, a first-seat microphone 5, a selector 6, an active noise control device 7, a control unit 8, an adding unit 9 for the first-seat speaker, an adding unit 10 for the second-seat speaker, and a speech sound relay unit 11.

[0039] like Figure 2 As shown, one seat of the car is referred to as the first seat, and another seat other than the first seat is referred to as the second seat. The first seat speaker 3 is a speaker for the user of the first seat arranged near the first seat, and the second seat speaker 4 is a speaker for the user of the second seat arranged near the second seat. Figure 2 The configuration is an example. As long as the first-seat speaker 6 mainly radiates sound to the user in the first seat and the second-seat speaker 5 mainly radiates sound to the user in the second seat, the configuration and number of the first-seat speaker 6 and the second-seat speaker 5 can be arbitrary.

[0040] In addition, the first seat microphone 5 is, for example, Figure 2 A microphone is placed near the first seat.

[0041] return Figure 1 The first-seat audio source 1 is a sound source that outputs sounds such as music listened to by the user in the first seat. The output sound A1 of the first-seat audio source 1 is output from the first-seat speaker 3 via the first-seat speaker adding unit 9.

[0042] The second-seat audio source 2 is a sound source that outputs sounds such as music listened to by the user in the second seat. The output sound A2 of the second-seat audio source 2 is output from the second-seat speaker 4 via the second-seat speaker adding unit 10 .

[0043] The selector 6 selectively outputs one of the speech sound signal Dp outputted from the active noise control device 7 and the output sound A2 from the second row sound source 2 as the reference sound Ref to the active noise control device 7 .

[0044] Active noise control device 7 generates and outputs a speech sound signal Dp and a canceling sound C based on the reference sound Ref output by selector 6, the output sound A2 from the second-seat audio source 2, and the sound M picked up by the first-seat microphone 5. The speech sound signal Dp output from active noise control device 7 is output to selector 6 and then output from second-seat speaker 4 via speech sound relay unit 11 and second-seat speaker adder 10. Furthermore, the canceling sound C output from active noise control device 7 is output from first-seat speaker 3 via first-seat speaker adder 9.

[0045] then, Figure 3 The structure of active noise control device 7 is shown.

[0046] As shown in the figure, the active noise control device 7 includes: a first variable filter 71, a first adaptive algorithm execution unit 72, a first estimation filter 73 with a transfer function S^(z) preset, a first subtractor 74, an auxiliary filter 75 with a transfer function H(z) preset, a first mute unit 76, a second estimation filter 77 with a transfer function S^(z) preset, and a second subtractor 78.

[0047] Here, the transfer function Ŝ(z) is a transfer characteristic Ŝ estimated by actual measurement or the like of the transfer function S(z) from the active noise control device 7 to the first seat microphone 5 .

[0048] Furthermore, the reference sound Ref input from the selector 6 passes through the first variable filter 71 and is output from the first-seat speaker 3 as the cancellation sound C via the first-seat speaker adder 9. The first mute unit 76 mutes (mutes) the output of the cancellation sound C to the first-seat speaker 3 under the control of the control unit 8.

[0049] The output of first variable filter 71 is also sent to second estimation filter 77. Second estimation filter 77 convolves the output of first variable filter 71 with the transfer characteristic S^(z) and outputs the result to second subtractor 78. Second subtractor 78 subtracts the output of second estimation filter 77 from the sound M picked up by first-seat microphone 5. The output of second subtractor 78 is sent to selector 6 as speech signal Dp and is then output from second-seat speaker 4 via speech signal relay unit 11 and second-seat speaker adder 10.

[0050] Furthermore, the reference sound Ref input from the selector 6 is sent to the first subtractor 74 through the auxiliary filter 75 .

[0051] The first subtractor 74 subtracts the output of the auxiliary filter 75 from the sound picked up by the first seat microphone 5 , and outputs the resulting subtraction signal to the first adaptive algorithm execution unit 72 .

[0052] Auxiliary filter 75 is pre-set with a transfer function H(z) that corrects the signal actually output by first-seat microphone 5 so that the output of first subtractor 74 corresponds to the signal output from first-seat microphone 5 when first-seat microphone 5 is located at the ear of the user in the first seat. The method for setting transfer function H(z) of auxiliary filter 75 will be described later.

[0053] Next, the first estimation filter 73 convolves the transfer characteristic Ŝ(z) with the output of the selector 6 , and outputs the result to the first adaptive algorithm execution unit 72 .

[0054] The first variable filter 71 , the first adaptive algorithm execution unit 72 , and the estimated filter constitute a Filtered-X adaptive filter.

[0055] The first adaptive algorithm execution unit 72 uses the signal output from the first subtractor 74 as an error and executes an adaptive algorithm such as NLMS or LMS while using the output of the estimated filter to perform an adaptive operation of updating the transfer function W(z) of the first variable filter 71 so as to minimize the level of the signal output from the first subtractor 74.

[0056] Furthermore, the in-vehicle communication support system includes, as operating modes, an ICC mode in which the speech of the user in the first seat picked up by the first-seat microphone 5 is output from the second-seat speaker 4 , and a non-ICC mode in which the speech of the user in the first seat picked up by the first-seat microphone 5 is not output from the second-seat speaker 4 .

[0057] Furthermore, in the non-ICC mode, the control unit 8 controls the selector 6 to output the output sound A2 of the second-seat audio source 2 as the reference sound Ref to the active noise control device 7 and controls the speech sound relay unit 11 to mute the output of the speech sound signal Dp to the second-seat speaker 4 .

[0058] Therefore, in non-ICC mode, the adaptive operation of the first adaptive algorithm execution unit 72 updates the transfer function W(z) of the first variable filter 71 so that the component of the output sound A2 from the second-seat audio source 2 included in the output of the first subtractor 74 is minimized. As a result, the first variable filter 71 adapts to output the cancellation sound C that cancels the sound output from the second-seat audio source 2 at the ear position of the user in the first seat.

[0059] On the other hand, in the ICC mode, the control unit 8 unmutes the speech signal Dp outputted from the speech relay unit 11 to the second seat speaker 4 and causes the selector 6 to output the speech signal Dp as the reference sound Ref to the active noise control device 7 .

[0060] Therefore, in ICC mode, the transfer function W(z) of the first variable filter 71 is updated through the adaptive operation of the first adaptive algorithm execution unit 72 to minimize the speech signal Dp component included in the output of the first subtractor 74. The speech signal Dp is the signal obtained by removing the cancellation sound C component included in the output of the first-seat microphone 5 from the sound M picked up by the first-seat microphone 5. Therefore, if the output of the first-seat microphone 5 includes the speech of the user in the first seat, the first variable filter 71 adapts to output the cancellation sound C. This cancellation sound C cancels the speech component of the user in the first seat outputted from the second-seat speaker 4 at the ear position of the user in the first seat. Furthermore, the speech component of the user in the first seat picked up by the first-seat microphone 5 near the ear position of the user in the first seat and outputted from the second-seat speaker 4 is also canceled and suppressed by the output of the cancellation sound C. Furthermore, by outputting the speech signal Dp to the second-seat speaker 4, the speech of the user in the first seat is outputted from the second-seat speaker 4 to the user in the second seat.

[0061] Hereinafter, the mode switching process performed by the control unit 8 when switching between the ICC mode and the non-ICC mode will be described.

[0062] Figure 4 Indicates the order of the mode switching process.

[0063] As shown in the figure, when the control unit 8 switches the operation mode from the ICC mode to the non-ICC mode (step 402 ), it first causes the speech sound relay unit 11 to mute the output of the speech sound signal Dp to the second seat speaker 4 (step 404 ).

[0064] Then, the adaptive operation of the active noise control device 7 is stopped by stopping the updating of the transfer function W(z) of the first variable filter 71 (step 406). More specifically, the updating of the transfer function W(z) of the first variable filter 71 is stopped by setting the step size to 0. This step size determines the gain of the transfer function W(z) update performed by the first adaptive algorithm execution unit 72.

[0065] Furthermore, the first mute unit 76 is caused to mute the output of the cancellation sound C (step 408 ).

[0066] Then, an initial transfer function predetermined for the non-ICC mode is set in the first variable filter 71 as the transfer function W(z) (step 410 ).

[0067] Next, the reference sound Ref outputted by the selector 6 is switched to the output sound A2 of the second audio source (step 412 ), and a predetermined time is waited (step 414 ). The predetermined time corresponds to the delay of each filter of the active noise control device 7 .

[0068] Then, the output of the cancellation sound C by the first mute unit 76 is muted (step 416), and the adaptive operation of the active noise control device 7 is started (step 418). More specifically, in step 418, the step size, which determines the gain for updating the transfer function W(z) by the first adaptive algorithm execution unit 72, is restored to its original value before the adaptive operation was stopped in step 406.

[0069] On the other hand, when the control unit 8 switches the operation mode from the non-ICC mode to the ICC mode (step 422), it stops updating the transfer function W(z) of the first variable filter 71, thereby stopping the adaptive operation of the active noise control device 7 (step 424), and unmutes the output of the speech sound signal Dp of the speech sound relay unit 11 to the second seat speaker 4 (step 426).

[0070] Then, the first mute unit 76 is muted to output the cancellation sound C (step 428 ), and the initial transfer function predetermined for the ICC mode is set in the first variable filter 71 as the transfer function W(z) (step 430 ).

[0071] Next, the reference sound Ref outputted from the selector 6 is switched to the speech sound signal Dp (step 432 ), and a predetermined time is waited (step 434 ). The predetermined time is set to a time corresponding to the delay of each filter of the active noise control device 7 .

[0072] The output of the cancellation sound C by the first mute unit 76 is muted (step 436 ), and the adaptive operation of the active noise control device 7 is started (step 438 ).

[0073] The mode switching process performed by the control unit 8 has been described above.

[0074] Next, a method of setting the transfer function H(z) of the auxiliary filter 75 of the active noise control device 7 will be described.

[0075] The transfer function H(z) of the auxiliary filter 75 is set in advance, for example, by performing the following first-stage learning process and second-stage learning process while the sound outputted by the second-seat audio source 2 is outputted from the second-seat speaker 4 .

[0076] The first stage of learning processing uses Figure 5 The first stage learning processing unit 100 shown in a and the learning microphone 200 arranged at the position of the ear of the user in the first seat are used for the learning.

[0077] The first-stage learning processing unit 100 includes a learning estimation filter 101 in which an estimated value Sv^(z) of the transfer function S^(z) from the first-stage learning processing unit 100 to the learning microphone 200 is set, a first-stage learning variable filter 102, and a first-stage learning adaptive algorithm execution unit 103.

[0078] In this configuration, the sound output by the second-seat audio source 2 is input to the first-stage learning variable filter 102, and the output of the first-stage learning variable filter 102 is output to the first-seat speaker 3. Furthermore, the first-stage learning adaptive algorithm execution unit 103 uses the output of the learning microphone 200 as an error and, while utilizing the output of the learning estimation filter 101, executes an adaptive algorithm such as NLMS or LMS to update the transfer function W(z) of the first-stage learning variable filter 102.

[0079] Then, by executing the adaptive algorithm, the transfer function W(z) of the first-stage learning variable filter 102 that has converged and stabilized can be obtained as a result of the first-stage learning process.

[0080] Next, the second stage of learning process uses Figure 5 The second stage learning processing unit 300 shown in b is performed.

[0081] The second-stage learning processing unit 300 includes a second-stage learning fixed filter 301 that sets the transfer function W(z) obtained as a result of the first-stage learning process as the transfer function, a second-stage learning variable filter 302, a second-stage learning adaptive algorithm execution unit 303, and a second-stage learning subtractor 304.

[0082] Furthermore, in such a configuration, the sound outputted from the second-seat audio source 2 passes through the second-stage learning fixed filter 301 and is then outputted to the first-seat speaker 3 .

[0083] Furthermore, the sound output by the second-seat audio source 2 passes through the second-stage learning variable filter 302 and is then sent to the second-stage learning subtractor 304. The second-stage learning subtractor 304 subtracts the output of the second-stage learning variable filter 302 from the signal picked up by the first-seat microphone 5 and outputs the result.

[0084] The second-stage learning adaptive algorithm execution unit 303 uses the sound output by the second-seat audio source 2 and the output of the second-stage learning subtracter 304 as an error to execute an adaptive algorithm such as NLMS or LMS, thereby updating the transfer function H(z) of the second-stage learning variable filter 302.

[0085] Then, through execution of the adaptive algorithm, the converged and stable transfer function H(z) is used as the transfer function H(z) of the auxiliary filter 75 of the active noise control device 7 .

[0086] Here, the transfer function H(z) of the auxiliary filter 75 learned as described above becomes, as described above, a transfer function that allows one to expect that the output of the first subtractor 74 in the active noise control device 7 will be a signal output from the first-seat microphone 5 when the first-seat microphone 5 is located at the position of the ear of the user in the first seat.

[0087] The first embodiment of the present invention has been described above.

[0088] Next, a second embodiment of the present invention will be described.

[0089] The in-vehicle communication support system of the second embodiment applies the in-vehicle communication support system of the first embodiment, and differs from the in-vehicle communication support system of the first embodiment only in that: Figure 6 As shown, the output sound A1 of the first audio source is input to the active noise control device 7 , the internal structure of the active noise control device 7 , and the content of the mode switching process performed by the control unit 8 .

[0090] Figure 7The configuration of active noise control device 7 according to the second embodiment is shown.

[0091] As shown in the figure, the active noise control device 7 has a structure that adds a first gain adjustment unit 701, a second gain adjustment unit 702, a third gain adjustment unit 703, a second variable filter 704, a second adaptive algorithm execution unit 705, a fixed filter 706, a third subtractor 707, and a first adder 708 to the structure shown in the first embodiment.

[0092] However, in the second embodiment, the output of the first subtractor 74 is sent to the third subtractor 707 , and the output of the third subtractor 707 is output to the first adaptive algorithm execution unit 72 instead of the output of the first subtractor 74 .

[0093] The first gain adjustment unit 701 adjusts the gain of the reference sound Ref input from the selector 6 to the first variable filter 71 , the first estimation filter 73 , and the auxiliary filter 75 .

[0094] The second gain adjustment unit 702 adjusts the gain of the output sound A1 of the first seat audio source 1 and outputs the adjusted gain to the second variable filter 704 and the second adaptive algorithm execution unit 705 .

[0095] The third gain adjustment unit 703 adjusts the gain of the output sound A2 of the second seat audio source 2 and outputs the adjusted sound to the fixed filter 706 .

[0096] The third subtractor 707 outputs a signal obtained by subtracting the output of the second variable filter 704 from the output of the first subtractor 74 to the first adaptive algorithm execution unit 72 and the second adaptive algorithm execution unit 705 .

[0097] The first adaptive algorithm execution unit 72 executes an adaptive algorithm using the signal output from the third subtractor 707 as an error, and performs an adaptive operation of updating the transfer function W(z) of the first variable filter 71 so that the level of the signal output from the third subtractor 707 becomes minimum.

[0098] Second variable filter 704 and second adaptive algorithm execution unit 705 also constitute an adaptive filter. Second adaptive algorithm execution unit 705 performs an adaptive operation by executing an adaptive algorithm such as NLMS or LMS using the output sound A1 of first-seat audio source 1 and the signal output from third subtractor 707 as an error, thereby updating the transfer function U(z) of second variable filter 704 so as to minimize the level of the signal output from third subtractor 707. This adaptive operation updates transfer function U(z) of second variable filter 704 so that the component of output sound A1 of first-seat audio source 1 contained in the signal output from third subtractor 707 is minimized.

[0099] The output of the fixed filter 706 is added to the output of the first variable filter 71 in the first adder 708 and then output as a part of the canceled sound C from the first seat speaker 3 via the first seat speaker adder 9.

[0100] In the non-ICC mode, the control unit 8 causes the selector 6 to output the output sound A2 of the second-seat audio source 2 to the active noise control device 7 as the reference sound Ref, causes the speech sound relay unit 11 to mute the output of the speech sound signal Dp to the second-seat speaker 4, and stops the output of the fixed filter 706.

[0101] Therefore, in non-ICC mode, the transfer function W(z) of the first variable filter 71 is updated through the adaptive operation of the first adaptive algorithm execution unit 72 so as to minimize the component of the output sound A2 from the second-seat audio source 2 included in the output of the third subtractor 707. As a result, the first variable filter 71 adapts to output the cancellation sound C for canceling the sound output from the second-seat audio source 2 at the position of the ear of the user in the first seat.

[0102] Here, the adaptive operation of the first adaptive algorithm execution unit 72 is performed through the second variable filter 704, the second adaptive algorithm execution unit 705, and the third subtractor 707, using the signal obtained by minimizing the component of the output sound A1 of the first seat audio source 1 in the output of the first subtractor 74 as an error.

[0103] Therefore, it can be expected that the first variable filter 71 can more appropriately generate the cancellation sound C for canceling the sound output by the second-seat audio source 2 at the position of the ear of the user in the first seat.

[0104] On the other hand, when in the ICC mode, the control unit 8 operates the fixed filter 706 with the transfer function W(z) of the first variable filter 71 in the non-ICC mode immediately before switching to the ICC mode set as the transfer function R(z). The control unit 8 unmutes the output of the speech sound signal Dp from the speech sound relay unit 11 to the second seat speaker 4, and causes the selector 6 to output the speech sound signal Dp as the reference sound Ref to the active noise control device 7.

[0105] Therefore, in the ICC mode, the transfer function W(z) of the first variable filter 71 is updated through the adaptive action of the first adaptive algorithm execution unit 72 so as to minimize the component of the speech sound signal Dp included in the output of the first subtractor 74. The first variable filter 71 is adapted to output the cancellation sound C, which cancels the speech sound component of the user in the first seat output from the second seat speaker 4 at the position of the ear of the user in the first seat.

[0106] Here, the adaptive operation of the first adaptive algorithm execution unit 72 is performed through the second variable filter 704, the second adaptive algorithm execution unit 705, and the third subtractor 707, using as an error the signal obtained by minimizing the component of the output sound A1 of the first-seat audio source 1 in the output of the first subtractor 74. Therefore, it can be expected that the cancellation sound C for canceling the speech sound component of the user in the first seat outputted from the second-seat speaker 4 at the position of the ear of the user in the first seat can be more appropriately generated by the first variable filter 71.

[0107] Furthermore, the speech sound component of the user in the first seat, picked up by the first seat microphone 5 located near the ear of the user in the first seat, and output from the second seat speaker 4, is also canceled and suppressed by the output of the cancellation sound C. Furthermore, by outputting the speech sound signal Dp to the second seat speaker 4, the speech sound of the user in the first seat is output from the second seat speaker 4 to the user in the second seat.

[0108] Furthermore, the output of the fixed filter 706, in which the transfer function W(z) of the first variable filter 71 in the non-ICC mode is set as the transfer function R(z), is output as part of the cancellation sound C. Therefore, the sound output by the audio source 2 at the second seat can also be cancelled at the position of the ear of the user at the first seat.

[0109] Hereinafter, in the second embodiment, a mode switching process performed by the control unit 8 when switching between the ICC mode and the non-ICC mode will be described.

[0110] Figure 8 The steps of the mode switching process are shown.

[0111] As shown in the figure, when the control unit 8 switches the operating mode from the ICC mode to the non-ICC mode (step 802), it causes the speech sound relay unit 11 to mute the output of the speech sound signal Dp to the second seat speaker 4 (step 804), stops the adaptive operation of the active noise control device 7 by stopping the updating of the transfer function W(z) of the first variable filter 71 (step 806), and causes the first mute unit 76 to mute the output of the cancellation sound C (step 808).

[0112] Then, the output of the fixed filter 706 is stopped (step 810), and the initial transfer function W(z) predetermined for the non-ICC mode is set in the first variable filter 71 (step 812).

[0113] Next, the reference sound Ref outputted from the selector 6 is switched to the output sound A2 of the second audio source (step 814 ), and the gains of the first gain adjustment unit 701 , the second gain adjustment unit 702 , and the third gain adjustment unit 703 are adjusted (step 816 ).

[0114] Then, a time corresponding to the delay of each filter of the active noise control device 7 is set as a predetermined time, and the predetermined time is waited (step 818), the output of the cancellation sound C of the first mute unit 76 is unmuted (step 820), and the adaptive operation of the active noise control device 7 is started (step 822).

[0115] On the other hand, when the control unit 8 switches the operation mode from the non-ICC mode to the ICC mode (step 832), it stops the updating of the transfer function W(z) of the first variable filter 71, thereby stopping the adaptive operation of the active noise control device 7 (step 834), causing the speech sound relay unit 11 to unmute the output of the speech sound signal Dp to the second seat speaker 4 (step 836), and causing the first mute unit 76 to mute the output of the cancellation sound C (step 838).

[0116] Then, the transfer function of the first variable filter 71 is obtained and set as the transfer function of the fixed filter 706, and the fixed filter 706 is operated (step 840). In addition, the initial transfer function preset for the ICC mode is set as the transfer function W(z) for the first variable filter 71 (step 842).

[0117] Next, the reference sound Ref outputted from the selector 6 is switched to the speech sound signal Dp (step 844 ), and the gains of the first gain adjustment unit 701 , the second gain adjustment unit 702 , and the third gain adjustment unit 703 are adjusted (step 846 ).

[0118] Then, a time corresponding to the delay of each filter of the active noise control device 7 is set as a prescribed time, and the prescribed time is waited (step 848), the output of the cancellation sound C of the first mute unit 76 is unmuted (step 850), and the adaptive action of the active noise control device 7 is started (step 852).

[0119] The embodiments of the present invention have been described above.

[0120] Furthermore, in the above-mentioned embodiments, the case where one first-seat speaker 3 , one second-seat speaker 4 , and one first-seat microphone 5 are provided is shown, but a plurality of these may be provided.

[0121] In addition, in the above embodiments, the case where the sound of the audio source 2 at the second seat is canceled for the user at the first seat and the speech sound of the user at the first seat is output to the speaker 4 at the second seat is described. However, this embodiment can also be applied to a case where the sound of the audio source at other seats is canceled for the users at each seat and the speech sound of the users at each seat is output to the speakers at the other seats.

[0122] Furthermore, the above embodiments can also be extended to a case where the audio source for each seat is multi-channel, and can be extended to cancel the sounds of the audio sources in other seats for the user's left and right ears respectively.

[0123] Furthermore, the auxiliary filter 75 of the active noise control device 7 in each of the above embodiments may be omitted. In this case, the same effect can be obtained to a certain extent.

[0124] Description of Reference Numerals

[0125] 1…First-seat audio source, 2…Second-seat audio source, 3…First-seat speaker, 4…Second-seat speaker, 5…First-seat microphone, 6…Selector, 7…Active noise control device, 8…Control unit, 9…Adder for first-seat speaker, 10…Adder for second-seat speaker, 11…Speech sound relay unit, 71…First variable filter, 72…First adaptive algorithm execution unit, 73…First estimation filter, 74…First subtractor, 75…Auxiliary filter, 76…First muting unit, 77…Second estimation filter, 78…Second subtractor, 100…First-stage learning processing unit, 101…Learning estimation filter, 102…variable filter for first-stage learning, 103…adaptive algorithm execution unit for first-stage learning, 200…learning microphone, 300…second-stage learning processing unit, 301…fixed filter for second-stage learning, 302…variable filter for second-stage learning, 303…adaptive algorithm execution unit for second-stage learning, 304…subtractor for second-stage learning, 701…first gain adjustment unit, 702…second gain adjustment unit, 703…third gain adjustment unit, 704…second variable filter, 705…second adaptive algorithm execution unit, 706…fixed filter, 707…third subtractor, 708…first adder.

Claims

1. An in-vehicle communication support system, mounted on a vehicle having a first seat and a second seat that are different from each other, the in-vehicle communication support system comprising: The second seat sound source device is a sound source device for the second seat; The second-seat speaker is a speaker for a user of the second seat and outputs the output sound of the second-seat sound source device; a microphone for receiving the voice of the first seat; A noise control unit outputs a cancellation sound and a speech sound signal; A first-seat speaker is a speaker for a user in the first seat, which outputs the cancellation sound output by the noise control unit; a selector that selectively outputs one of the output sound of the second seat sound source device and the speech sound signal output by the noise control unit as a reference sound to the noise control unit; and Control Department, The noise control unit includes: an error signal generating unit that uses the output of the microphone to generate an error signal including a component of the reference sound in the output of the microphone; a first adaptive filter, taking the reference sound as input and performing an adaptive operation of updating a transfer function to reduce the magnitude of the error signal, thereby generating the cancellation sound; as well as a speech sound signal generating unit that generates, as the speech sound signal, a signal including a component of a speech sound of the user at the first seat in the output of the microphone; The in-vehicle communication support system has two operation modes: a first operation mode in which the speech sound signal output by the noise control unit is not output from the second seat speaker; and a second operation mode in which the speech sound signal output by the noise control unit is output from the second seat speaker. In the first operation mode, the control unit causes the selector to output the sound output by the second seat sound source device as the reference sound to the noise control unit, and in the second operation mode, the control unit causes the selector to output the speech sound signal output by the noise control unit as the reference sound to the noise control unit. The noise control unit includes an auxiliary filter that receives the reference sound as input. The error signal generating unit generates, as the error signal, a signal obtained by subtracting at least the output of the auxiliary filter from the output of the microphone. By subtracting the output of the auxiliary filter from the output of the microphone, a previously determined transfer function is set for the auxiliary filter. This transfer function is a transfer function that corrects the sound collected by the microphone to the sound collected at the listening position of the user in the first seat.

2. The in-vehicle communication support system according to claim 1, wherein: The speech sound signal generating unit generates, based on the output of the microphone, a signal from which the canceling sound component has been removed as the speech sound signal.

3. The in-vehicle communication support system according to claim 2, wherein: The speech sound signal generation unit generates the speech sound signal by subtracting a signal obtained by applying a transfer function of a transmission path to the microphone to the cancelling sound from the output of the microphone.

4. The in-vehicle communication support system according to claim 1, wherein: A first-seat sound source device is provided, the first-seat sound source device outputting output sound from the first-seat speaker. The noise control unit generates, as the error signal, a signal obtained by subtracting at least the first seat sound source canceling sound from the output of the microphone.

5. The in-vehicle communication support system according to claim 4, wherein: The noise control unit includes: a fixed filter that receives the output sound of the second-seat sound source device as input and outputs the second-seat sound source cancellation sound; and an adding unit that adds the second seat sound source cancellation sound to the cancellation sound and outputs the resultant sound from the first seat speaker; In the first operation mode, the control unit does not cause the adding unit to add the second seat sound source canceling sound to the canceling sound, and in the second operation mode, causes the adding unit to add the second seat sound source canceling sound to the canceling sound.

6. The in-vehicle communication support system according to claim 5, wherein: When the operation mode is switched from the first operation mode to the second operation mode, the control unit sets the transfer function of the first adaptive filter before the switching as the transfer function of the fixed filter.

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