Active noise control system

Abstract

An active noise control system is provided which uses a single microphone to cancel noise for multiple seats. A first seat noise control device (3) corrects sound picked up by the microphone (9) to sound at a listening position of a user seated at the first seat, uses the sound as an error, uses an adaptive filter with sound of a second seat audio source (2) as input to generate a cancellation sound which cancels sound of the second seat audio source (2) at the first seat, and outputs from a first seat speaker (7). A second seat noise control device (4) corrects sound picked up by the microphone (9) to sound at a listening position of a user seated at the second seat, uses the sound as an error, uses an adaptive filter with sound of the first seat audio source (1) as input to generate a cancellation sound which cancels sound of the first seat audio source (1) at the second seat, and outputs from a second seat speaker (8).

Description

Technical Field

[0001] This invention relates to a technique for active noise control (ANC) that reduces noise by propagating noise cancellation tones that cancel out noise. Background Technology

[0002] As an active noise control technique that reduces noise by propagating noise-canceling tones that cancel out noise, the following active noise control (ANC) technique is known (e.g., Patent Documents 1 and 2): a microphone is provided near the noise cancellation position, a speaker outputs noise-canceling tones that cancel out noise at the noise cancellation position, and an adaptive filter is provided to generate the noise-canceling tones output from the speaker by applying an adaptively set transfer function to the output signal of the noise source or a signal simulating the output signal; in the adaptive filter, the transfer function is adaptively set as an error signal using a signal whose output of the microphone has been corrected by an auxiliary filter.

[0003] Here, in this technology, the auxiliary filter is provided with a transfer function that has been pre-learned using a learning microphone configured at the noise cancellation position, and which 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 cancelled at a noise cancellation position that is different from the position of the microphone.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-12917

[0007] Patent Document 2: Japanese Patent Application Publication No. 2018-72770 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] In an environment where users in seat 1 and seat 2 each receive sound from a different audio source from the speaker in seat 1 and a different audio source from the speaker in seat 2, respectively, and the active noise control technology described above is applied to prevent users from hearing the audio sources that other users are listening to, the following problem occurs.

[0010] That is, each seat in each of the various seats requires a microphone, which increases the scale and cost of the system.

[0011] Furthermore, for example, if the first and second seats are arranged one in front of the other, and each seat is equipped with a speaker that outputs noise cancellation for the user in that seat, for the user in the front seat, even if the user's listening position is changed to a position further forward than the noise cancellation position set for the front seat, the attenuation of the second sound source that can be heard from the rear seat direction increases with this change, so the weakening effect of the noise cancellation from the second sound source is not easily felt. However, for the user in the rear seat, if the user's listening position is changed to a position further forward than the noise cancellation position set for the rear seat, the sound of the first sound source that can be heard from the front seat direction increases with this change, so the user feels more uncomfortable due to the weakening effect of the noise cancellation from the second sound source.

[0012] Therefore, the purpose of this invention is to apply active noise control technology to each user of the arranged seats in a simple structure to eliminate noise for that user.

[0013] Furthermore, the purpose of this invention is to eliminate noise for each user in the seating arrangement by applying active noise control technology, while suppressing the discomfort caused by the weakening of the noise elimination effect as the user's head moves.

[0014] Methods used to solve problems

[0015] To achieve the aforementioned objectives, the present invention provides an active noise control system, which is applied to an environment in which a first tone of sound, as a first sound source, is output to a user seated at a first seat, and a second tone of sound, as a second sound source, is output to a user seated at a second seat. The active noise control system comprises: a first loudspeaker; a second loudspeaker; a microphone; a first noise control device that outputs a first canceling tone from the first loudspeaker, the first canceling tone serving as a sound to cancel the second tone for the user seated at the first seat; and a second noise control device that outputs a second canceling tone from the second loudspeaker, the second canceling tone serving as a sound to cancel the first tone for the user seated at the second seat.

[0016] Here, the aforementioned first noise control device includes: a first auxiliary filter that takes the second tone as input; a first correction unit that uses the output of the first auxiliary filter to correct the output of the microphone and outputs it as a first error signal; and a first adaptive filter that takes the second tone as input, uses the first error signal as an error, and performs an adaptive operation to update its own transfer function to generate the first canceled tone. Furthermore, the first auxiliary filter is provided with a transfer function that is predetermined, such that the correction performed by the first correction unit using the output of the first auxiliary filter corrects the component of the second tone contained in the microphone output to a component of the second tone contained in the sound transmitted to the first canceled position, which is a position that can be the listening position for the user seated in the first seat.

[0017] Furthermore, the aforementioned second noise control device includes: a second auxiliary filter, which takes the first tone as input; a second correction unit, which uses the output of the second auxiliary filter to correct the output of the microphone and outputs it as a second error signal; and a second adaptive filter, which takes the first tone as input, and performs an adaptive operation to update its own transfer function by taking the second error signal as an error, thereby generating the second canceled tone. Moreover, the second auxiliary filter is provided with a transfer function that is predetermined, such that the correction performed by the second correction unit using the output of the second auxiliary filter corrects the component of the first tone contained in the microphone output to a component of the first tone contained in the sound transmitted to the second cancellation position, which is a position that can be the listening position for the user seated in the second seat.

[0018] According to such an active noise control system, when the first tone and the second tone are unrelated, it is possible to eliminate the first tone output to the first seat at the second seat and the second tone output to the second seat at the second seat without setting up microphones according to each seat.

[0019] Here, in this active noise control system, the direction from the first seat to the second seat may be defined as the direction, and the microphone may be positioned between the first speaker and the second speaker with respect to the defined direction.

[0020] Alternatively, in these active noise control systems, the direction from the first seat to the second seat may be defined as the direction in which the first speaker, the microphone, and the second speaker are positioned between the listening positions of the user seated in the first seat and the user seated in the second seat; the microphone is positioned between the first speaker and the second speaker in the defined direction; the first sound is output from the first speaker toward the user seated in the first seat, and the second sound is output from the second speaker toward the user seated in the second seat.

[0021] In this way, the outputs of the first and second loudspeakers that output the first and second cancel tones can be shared, simplifying the structure of the system as a whole.

[0022] Here, the above active noise control system can also be configured such that the second seat is located behind the first seat in the front-back direction; and the first speaker, the microphone, and the second speaker are located in the first seat.

[0023] In addition, in this case, the first speaker and the microphone may be placed in the headrest of the first seat, and the second speaker may be placed in the headrest or seat back of the first seat.

[0024] Alternatively, in the above active noise control system, the second seat can be set as a seat arranged in the left-right direction with the first seat.

[0025] Alternatively, at least one of the first speaker, the microphone, and the second speaker of the above-mentioned active noise control system may be configured in the roof of the vehicle.

[0026] Here, when the second speaker is positioned between the listening position of the user seated in the first seat and the listening position of the user seated in the second seat, and the second sound is output from the second speaker toward the second seat, the active noise control system may also set the second seat to be a seat behind the first seat in a front-back direction; set the first cancellation position to the standard listening position of the user seated in the first seat; and set the second cancellation position to a position that is forward of the standard listening position of the user seated in the second seat and backward of the first seat.

[0027] In this way, when the user seated in the second seat is in the second cancellation position, which is forward of the standard listening position, the first note can be canceled well. Furthermore, when the user seated in the second seat is in a position further back than the standard listening position or other second cancellation positions, the volume of the first note heard from the front of the listening position is also smaller than when the listening position is in the second cancellation position. Therefore, the discomfort caused by the weakening cancellation effect due to the user's listening position being further back than the second cancellation position is suppressed.

[0028] Furthermore, the present invention provides an in-vehicle system mounted on a car having a first seat and a second seat located behind the first seat, comprising: a first sound output unit that outputs a first sound source to a user seated in the first seat; a second sound output unit that outputs a second sound source to a user seated in the second seat; a first noise control unit that outputs a first cancellation sound that best eliminates the second sound at a first cancellation position that is a standard sound listening position for the user seated in the first seat; and a first noise control unit that outputs a second cancellation sound that best eliminates the first sound at a second cancellation position that is a position further forward than the standard sound listening position for the user seated in the second seat and further backward than the first seat.

[0029] According to this in-vehicle system, when the listening position of the user in the second seat is in the second cancellation position, which is forward of the standard listening position, the first tone can be effectively cancelled. Furthermore, when the listening position of the user in the second seat is backward of the second cancellation position, the volume of the first tone heard from the direction of the first seat in front is also smaller, thus suppressing the discomfort caused by the weakening cancellation effect due to the user's listening position deviating from the second cancellation position.

[0030] Invention Effects

[0031] As described above, according to the present invention, active noise control technology can be applied to each user of the arranged seats in a simple structure to eliminate noise for that user.

[0032] Furthermore, it can apply active noise control technology to each user in the seating arrangement to eliminate noise for that user while suppressing the discomfort caused by the weakening of the noise reduction effect as the user's head moves. Attached Figure Description

[0033] Figure 1 This is a block diagram illustrating the structure of an in-vehicle system according to an embodiment of the present invention.

[0034] Figure 2 This is a diagram illustrating the configuration of the speakers and microphones in an in-vehicle system according to an embodiment of the present invention.

[0035] Figure 3 This is a block diagram illustrating the structure for learning the transfer function of an auxiliary filter according to an embodiment of the present invention.

[0036] Figure 4 This is a diagram illustrating an example configuration of a learning microphone according to an embodiment of the present invention.

[0037] Figure 5 This is a diagram illustrating another configuration example of the speaker and microphone of an in-vehicle system according to an embodiment of the present invention.

[0038] Figure 6 This is a diagram illustrating another configuration example of the speaker and microphone of an in-vehicle system according to an embodiment of the present invention.

[0039] Label Explanation

[0040] 1…First seat uses an audio source; 2…Second seat uses an audio source; 3…First seat uses a noise control device; 4…Second seat uses a noise control device; 5…First seat uses an adder; 6…Second seat uses an adder; 7…First seat uses a loudspeaker; 8…Second seat uses a loudspeaker; 9…Microphone; 31…First seat uses a variable filter; 32…First seat uses an adaptive algorithm execution unit; 33…First seat uses an estimation filter; 34…First seat uses an auxiliary filter; 35…First seat uses a subtractor; 41…Second seat uses a variable filter; 42…Second seat uses an adaptive algorithm execution unit. Execution unit; 43…Estimation filter for the second seat; 44…Auxiliary filter for the second seat; 45…Subtractor for the second seat; 50…First-stage learning processing unit; 51…Estimation filter for learning; 52…Variable filter for the first-stage learning; 53…Adaptive algorithm execution unit for the first-stage learning; 60…Microphone for learning; 70…Second-stage learning processing unit; 71…Fixed filter; 72…Variable filter for the second-stage learning; 73…Adaptive algorithm execution unit for the second-stage learning; 74…Subtractor for the second-stage learning. Detailed Implementation

[0041] The embodiments of the present invention will be described below.

[0042] exist Figure 1 The diagram shows the structure of the vehicle-mounted system according to this embodiment.

[0043] The in-vehicle system is a system installed in a car, as shown in the figure, and includes a first-seat audio source 1, a second-seat audio source 2, a first-seat noise control device 3, a second-seat noise control device 4, a first-seat additive unit 5, a second-seat additive unit 6, a first-seat speaker 7, a second-seat speaker 8, and a microphone 9.

[0044] The first seat is one of the front seats in a car, and the second seat is the seat directly behind the first seat.

[0045] The following explanation assumes that the first seat is the driver's seat and the second seat is the rear seat directly behind the driver's seat.

[0046] like Figure 2 a, Figure 2 As shown in b, the first speaker 7 is positioned in front of the driver's headrest to transmit sound forward, and the second speaker 8 is positioned behind the driver's headrest to transmit sound backward.

[0047] Furthermore, the microphone 9 is positioned on the headrest of the driver's seat so that its position in the forward and backward direction is between the first speaker 7 and the second speaker 8.

[0048] Back Figure 1 The first-seat audio source 1 is an audio source that outputs music and other sounds to the user of the first seat. The sound output from the first-seat audio source 1 is output from the first-seat speaker 7 via the first-seat addition unit 5.

[0049] In addition, the second-seat audio source 2 is an audio source that outputs music and other sounds to the user of the second seat. The sound output from the second-seat audio source 2 is output from the second-seat speaker 8 via the second-seat addition unit 6.

[0050] The sound of the second-seat audio source 2 and the sound picked up by the microphone 9 are input into the noise control device 3 for the first seat. Based on these input sounds, the noise control device 3 for the first seat generates a canceling tone that best eliminates the sound of the second-seat audio source 2 at the standard listening position of the user seated in the first seat. The canceling tone is output from the speaker 7 for the first seat via the addition unit 5 for the first seat.

[0051] Furthermore, in the noise control device 4 for the second seat, the sound of the audio source 1 for the first seat and the sound picked up by the microphone 9 are input. Based on these input sounds, the noise control device 4 for the second seat generates a canceling sound that best eliminates the sound of the audio source 1 for the first seat at a position slightly forward of the standard listening position of the user seated in the second seat. This canceling sound is output from the speaker 8 for the second seat via the addition unit 6 for the second seat.

[0052] The first noise control device 3 includes a first variable filter 31, a first adaptive algorithm execution unit 32, a first estimation filter 33 with a pre-set transfer function S1^(z), a first auxiliary filter 34 with a pre-set transfer function H1(z), and a first subtractor 35.

[0053] The sound input from the second-position audio source 2 to the first-position noise control device 3 is eliminated by the first-position variable filter 31 and output from the first-position speaker 7 via the first-position adder 5.

[0054] Furthermore, the sound input from the second-position audio source 2 to the first-position noise control device 3 is transmitted to the first-position subtractor 35 via the first-position auxiliary filter 34.

[0055] The first-position subtractor 35 subtracts the output of the first-position auxiliary filter 34 from the sound picked up by the microphone 9 and transmits it to the first-position adaptive algorithm execution unit 32.

[0056] A transfer function H1(z) is pre-set in the first-seat auxiliary filter 34. This transfer function H1(z) corrects the actual output signal of the microphone 9 so that the output of the first-seat subtractor 35 is the signal output from the microphone 9 when the microphone 9 is located in the standard listening position of the first-seat user. The method for setting the transfer function H1(z) of the first-seat auxiliary filter 34 will be described later.

[0057] Next, in the first-position estimation filter 33, there is a preset estimated transfer characteristic S1^(z) of the transfer function S1(z) from the first-position noise control device 3 to the microphone 9 estimated by actual measurement, etc. The first-position estimation filter 33 convolves the transfer characteristic S1^(z) into the input sound from the second-position audio source 2 and outputs it to the first-position adaptive algorithm execution unit 32.

[0058] The first-position variable filter 31, the first-position adaptive algorithm execution unit 32, and the first-position estimation filter 33 constitute the Filtered-X adaptive filter.

[0059] The first-position adaptive algorithm execution unit 32 uses the signal whose transfer function S1^(z) is convolved by the first-position estimation filter 33, and performs an adaptive operation to update the transfer function W1(z) of the first-position variable filter 31 by using the signal output from the first-position subtractor 35 as an error, employing an adaptive algorithm such as NLMS (Normalized Least Mean Square Adaptive Filtering) or LMS (Least Mean Square Adaptive Filtering). As a result, because the sound of the second-position audio source 2 used by the first-position adaptive algorithm execution unit 32 in the adaptation is unrelated to the sound of the first-position audio source 1, the first-position variable filter 31 is adaptively adjusted to eliminate the sound output from the second-position audio source at the standard listening position of the first-position user.

[0060] Next, the second noise control device 4 includes a second variable filter 41, a second adaptive algorithm execution unit 42, a second estimation filter 43 with a pre-set transfer function S2^(z), a second auxiliary filter 44 with a pre-set transfer function H2(z), and a second subtractor 45.

[0061] The sound input from the first-position audio source 1 to the second-position noise control device 4 passes through the second-position variable filter 41 and is output as a canceled sound via the second-position adder 6 from the second-position speaker 8.

[0062] Furthermore, the sound input from the first-seat audio source 1 to the second-seat noise control device 4 is transmitted to the second-seat subtractor 45 via the second-seat auxiliary filter 44.

[0063] The second subtractor 45 subtracts the output of the second auxiliary filter 44 from the sound picked up by the microphone 9 and transmits it to the second adaptive algorithm execution unit 42.

[0064] A transfer function H2(z) is pre-set in the auxiliary filter 44 for the second seat. This transfer function H2(z) corrects the actual output signal of the microphone 9 so that the output of the subtractor 45 for the second seat is the signal output from the microphone 9 when the microphone 9 is located slightly forward of the standard listening position of the user in the second seat. The method for setting the transfer function H2(z) of the auxiliary filter 44 for the second seat will be described later.

[0065] Next, in the second-position estimation filter 43, an estimated transfer characteristic S2^(z) is preset to estimate the transfer function S2(z) from the second-position noise control device 4 to the microphone 9 through actual measurement, etc. The second-position estimation filter 43 convolves the transfer characteristic S2^(z) into the input sound from the first-position audio source 1 and outputs it to the second-position adaptive algorithm execution unit 42.

[0066] The second-position variable filter 41, the second-position adaptive algorithm execution unit 42, and the second-position estimation filter 43 constitute the Filtered-X adaptive filter.

[0067] The second-position adaptive algorithm execution unit 42 uses the signal whose transfer function S2^(z) is convolved by the second-position estimation filter 43, and executes an adaptive algorithm such as NLMS or LMS using the signal output from the second-position subtractor 45 as an error to perform an adaptive operation that updates the transfer function W2(z) of the second-position variable filter 41.

[0068] Furthermore, as a result, since the sound of the first audio source 1 used in the adaptation by the second-position adaptive algorithm execution unit 42 is unrelated to the sound of the second-position audio source 2, the second-position variable filter 41 is adapted to eliminate the sound output by the first audio source in a manner that cancels out the sound at a position slightly ahead of the listening position of the second-position user.

[0069] Next, the method for setting the transfer function H1(z) of the first auxiliary filter 34 of the first noise control device 3 described above will be explained.

[0070] The transfer function H1(z) of the first auxiliary filter 34 is set, for example, by performing a first-stage learning process and a second-stage learning process in advance.

[0071] The first stage of learning involves processing... Figure 1 The vehicle's in-vehicle system will replace the first seat with a noise control device 3. Figure 3 The first-stage learning processing unit 50 shown in Figure a is connected to the learning microphone 60 in the structure.

[0072] Learning microphone 60 configuration in such Figure 4 As shown in a1 and a2, it is used in the standard listening position for the user who is seated in the first seat as the driver.

[0073] Back Figure 3 a. The first-stage learning processing unit 50 includes a learning estimation filter 51 with an estimated value S1v^(z) of the transfer function S1v(z) from the first-stage learning processing unit 50 to the learning microphone 60, a first-stage learning variable filter 52, and a first-stage learning adaptive algorithm execution unit 53.

[0074] Furthermore, in this structure, the sound output from the audio source 2 of the second seat is input to the learning estimation filter 51 and the first-stage learning variable filter 52, and the output of the first-stage learning variable filter 52 is output to the first seat speaker 7. In addition, the first-stage learning variable filter 52, the learning estimation filter 51, and the first-stage learning adaptive algorithm execution unit 53 constitute a Filtered-X adaptive filter. The first-stage learning adaptive algorithm execution unit 53 uses the output of the learning estimation filter 51 and takes the output of the learning microphone 60 as an error to execute an adaptive algorithm such as NLMS or LMS, and updates the transfer function W(z) of the first-stage learning variable filter 52.

[0075] Furthermore, through the execution of the adaptive algorithm, the transfer function W(z) of the variable filter 52 used for the first stage of learning, which is convergent and stable, is obtained as the result of the first stage of learning.

[0076] Next, the second phase of learning processing is in Figure 1 In the vehicle system, the first seat is replaced with noise control device 3. Figure 3 The second stage of learning processing is carried out in the structure of the learning processing unit 70 shown in b.

[0077] The second-stage learning processing unit 70 includes a fixed filter 71 that sets the transfer function W(z) obtained as a result of the first-stage learning processing as the transfer function, a variable filter 72 for second-stage learning, an adaptive algorithm execution unit 73 for second-stage learning, and a subtractor 74 for second-stage learning.

[0078] Furthermore, in this structure, the sound output from the second seat using the audio source 2 is passed through a fixed filter 71 and output to the first seat using the speaker 7.

[0079] Furthermore, the sound output from the second seat using the audio source 2 is transmitted to the second-stage learning subtractor 74 after passing through the second-stage learning variable filter 72. The second-stage learning subtractor 74 outputs the signal picked up by the microphone 9 after subtracting the output of the second-stage learning variable filter 72.

[0080] The second-stage adaptive algorithm execution unit uses the output of the second-stage learning subtractor 74 as the error to execute an adaptive algorithm such as NLMS or LMS, and updates the transfer function H(z) of the second-stage learning variable filter 72.

[0081] Furthermore, through the execution of the adaptive algorithm, the convergent and stable transfer function H(z) is set as the transfer function H1(z) of the first auxiliary filter 34 of the first noise control device 3.

[0082] Here, the transfer function H1(z) learned in this way can be expected to be the transfer function of the signal output from the microphone 9 when the microphone 9 is located in the standard listening position of the user in the first seat, as described above.

[0083] Next, the transfer function H2(z) of the second auxiliary filter 44 of the second noise control device 4 is set in the same way as the transfer function H1(z) of the first auxiliary filter 34, by... Figure 1 The second seat in the vehicle's in-vehicle system will be replaced with noise control device 4. Figure 3 The first-stage learning processing unit 50, shown in figure a, performs the first-stage learning in a structure in which the learning microphone 60 is connected to the first-stage learning processing unit 50. Figure 1 The second seat in the vehicle's in-vehicle system will be replaced with a noise control device 4. Figure 3 The second-stage learning processing is set up in the structure of the second-stage learning processing unit 70 shown in b.

[0084] Therefore, in the first stage of learning processing of the transfer function H2(z) of the second auxiliary filter 44, Figure 3 a, Figure 3 The second-seat audio source 2 of b is the first-seat audio source 1, the first-seat speaker 7 is the second-seat speaker 8, the first-seat adder 5 is the second-seat adder 6, and the second-seat adder 6 is the first-seat adder 5. Furthermore, in the first stage of learning processing of the transfer function H2(z) of the second-seat auxiliary filter 44, the learning microphone 60 is used as... Figure 4 b1, Figure 4 As shown in b2, the sound is positioned slightly forward of the standard listening position for the user in the second seat, which is located directly behind the driver's seat. Furthermore, in the learning estimation filter 51 of the first-stage learning processing unit 50, the settings from the first-stage learning processing unit 50 to... Figure 4 b1, Figure 4 The estimated value of the transfer function S1v(z) of the learning microphone 60 configured as shown in b2.

[0085] Furthermore, the transfer function H(z) of the second-stage learning variable filter 72 of the second-stage learning processing unit 70, which converges and stabilizes in the second-stage learning process, is used as the transfer function H2(z) of the second-stage auxiliary filter 44 of the second-stage noise control device 4.

[0086] The transfer function H2(z) learned in this way can be expected to become, as described above, the output of the second-seat subtractor 45 in the second-seat noise control device 4, which is the transfer function of the signal output from the microphone 9 when the microphone 9 is located slightly in front of the standard listening position of the second-seat user.

[0087] The embodiments of the present invention have been described above.

[0088] Thus, according to this embodiment, it is possible to use the same microphone 9 to cancel the sound of the first seat and the second seat from the audio source that is unrelated to the other seat, without setting up microphones 9 for each seat. Furthermore, since the output of the audio source sound and the output of the canceled sound can be shared by the speaker 7 for the first seat and the speaker 8 for the second seat, the structure of the vehicle system can be simplified.

[0089] Furthermore, in this embodiment, since the noise control device 4 for the second seat generates a cancellation tone that best eliminates the sound of the audio source 1 for the first seat at a position slightly forward of the standard listening position of the user seated in the second seat, the first tone can also be effectively eliminated even when the user seated in the second seat is in a position forward of the standard listening position. Moreover, in this case, although the cancellation effect weakens when the user seated in the second seat is in a position further back than the standard listening position, the volume of the audio source 1 for the first seat that can be heard from in front of the listening position also decreases, thus suppressing any discomfort caused by the weakening cancellation effect.

[0090] Alternatively, the above implementation can also be configured in two sets, consisting of a microphone 9, a first-seat speaker 7, a second-seat speaker 8, a first-seat adder 5, a second-seat adder 6, a first-seat noise control device 3, and a second-seat noise control device 4. In this configuration, the sound from the second-seat audio source 2 is eliminated from the left and right ears of the first-seat user, and the sound from the first-seat audio source 1 is eliminated from the left and right ears of the second-seat user.

[0091] That is, in this case, for example, Figure 5 As shown in Figure a, the first headrest is positioned on the left side by a first-seat speaker 7a (which transmits sound towards the standard left ear of the first-seat user), a first-seat microphone 9a, and a first-seat speaker 8a (which transmits sound towards the standard left ear of the second-seat user). The first headrest is positioned on the right side by a second-seat speaker 7b (which transmits sound towards the standard right ear of the first-seat user), a second-seat microphone 9b, and a second-seat speaker 8b (which transmits sound towards the standard right ear of the second-seat user).

[0092] Furthermore, in this case, the first-position adaptive algorithm execution unit 32 of the first-position noise control device 3 of the first group and the first-position noise control device 3 of the second group performs an adaptive operation to update the transfer function W1(z) of the first-position variable filter 31 by taking the signal output from the first-position subtractor 35 of its own group and the signal output from the first-position subtractor 35 of the other group as errors. The second-position adaptive algorithm execution unit 42 of the second-position noise control device 4 of the first group and the second-position noise control device 4 of the second group performs an adaptive operation to update the transfer function W2(z) of the second-position variable filter 41 by taking the signal output from the second-position subtractor 45 of its own group and the signal output from the second-position subtractor 45 of the other group as errors.

[0093] Furthermore, in this case, such as Figure 5 As shown in b, using the first left learning microphone 60a positioned at the standard left ear position of the first user, the first right learning microphone 60b positioned at the standard right ear position of the first user, the second left learning microphone 60c positioned slightly forward of the standard left ear position of the second user, and the second right learning microphone 60d positioned slightly forward of the standard right ear position of the second user, as the transfer function H1(z) of the first auxiliary filter 34 of the first group of the first noise control device 3, the transfer function H1(z) corrected by the subtraction of the first subtractor 35 for the difference between the output of microphone 9a and the output when microphone 9a is positioned at the first left learning microphone 60a is obtained, as the first auxiliary filter 34 of the second group of the first noise control device 3. The transfer function H1(z) is obtained; the difference between the output of microphone 9b and the output when microphone 9b is in the position of the first seat right learning microphone 60b is corrected by the subtraction of the first seat subtractor 35, and is used as the transfer function H2(z) of the second seat auxiliary filter 44 of the second seat noise control device 4 of the first group; the difference between the output of microphone 9a and the output when microphone 9a is in the position of the second seat left learning microphone 60c is corrected by the subtraction of the second seat subtractor 45, and is used as the transfer function H2(z) of the second seat auxiliary filter 44 of the second seat noise control device 4 of the second group; the difference between the output of microphone 9b and the output when microphone 9b is in the position of the second seat right learning microphone 60d is corrected by the subtraction of the second seat subtractor 45.

[0094] Furthermore, the above-described embodiments can also be applied in the following situations: the sound of the first-position audio source 1 and the noise cancellation of the first-position noise control device 3 are output from the first-position speaker 7, and the sound of the second-position audio source 2 and the noise cancellation of the second-position noise control device 4 are output from the second-position speaker 8, but the sound of the first-position audio source 1 is output from a speaker separately located in front of the first position, the sound of the second-position audio source 2 is output from a speaker separately located between the first and second positions, the first-position speaker 7 outputs only the noise cancellation of the first-position noise control device 3, and the second-position speaker 8 outputs only the noise cancellation of the second-position noise control device 4.

[0095] Furthermore, the configuration of the first speaker 7, the second speaker 8, and the microphone 9 in this embodiment can also be... Figure 2 a, Figure 2 Configuration other than the one shown in b.

[0096] For example, it can also be like Figure 5 As shown in Figure c, a first speaker 7 for transmitting sound to the first seat is installed in the ceiling of the car interior, in front of the headrest; a second speaker 8 for transmitting sound to the second seat is installed in the ceiling of the car interior, in front of the headrest; and a microphone 9 is installed on the headrest of the first seat.

[0097] Or, it can be like Figure 5 As shown in Figure d, a first speaker 7 is installed in front of the driver's seat headrest to transmit sound forward, a second speaker 8 is installed on the back of the driver's seat to transmit sound backward, and a microphone 9 is installed at the rear of the driver's seat headrest.

[0098] Furthermore, regardless of the configuration, the microphone 9 is preferably positioned between the first speaker 7 and the second speaker 8 in the front-to-back direction.

[0099] Furthermore, it is preferable that the first speaker 7, the second speaker 8, and the microphone 9 are positioned close to each other, so that the impact of changes in the transmission path between the first speaker 7 and the microphone 9, and between the second speaker 8 and the microphone 9, is minimized.

[0100] Furthermore, the above implementation method can also be used as a seating arrangement where the first and second seats are arranged to the left and right.

[0101] That is, in this case, for example, the left seat in a left-right seating arrangement is designated as seat number 1, and the right seat as seat number 2, such as... Figure 6 As shown in a1, between the first and second seats, from left to right, a speaker 7 for the first seat that transmits sound to the left, a microphone 9, and a speaker 8 for the second seat that transmits sound to the right are arranged sequentially.

[0102] Furthermore, in this case, such as Figure 6 As shown in a2, the learning microphone 60e is positioned at the standard right ear position of the first-seat user to perform the first stage of learning processing of the transfer function H1(z) of the first-seat auxiliary filter 34 of the first-seat noise control device 3, and the learning microphone 60f is positioned at the standard left ear position of the second-seat user to perform the first stage of learning processing of the transfer function H2(z) of the second-seat auxiliary filter 44 of the second-seat noise control device 4.

[0103] However, the learning microphone 60 can also be positioned at the standard left ear position or the center position of the standard left and right ears of the first user to perform the first stage of learning processing of the transfer function H1(z) of the first auxiliary filter 34 of the first noise control device 3, and the learning microphone 60 can be positioned at the standard right ear position or the center position of the standard left and right ears of the second user to perform the first stage of learning processing of the transfer function H2(z) of the second auxiliary filter 44 of the second noise control device 4.

[0104] Furthermore, this embodiment can be extended. When the first and second seats are arranged as left and right seats, two sets of combinations of microphone 9, speaker 7 for the first seat, speaker 8 for the second seat, additive unit 5 for the first seat, additive unit 6 for the second seat, noise control device 3 for the first seat, and noise control device 4 for the second seat are also provided. The sound of audio source 2 for the second seat is canceled for each of the left and right ears of the user in the first seat, and the sound of audio source 1 for the first seat is canceled for each of the left and right ears of the user in the second seat.

[0105] That is, in this case, for example, Figure 6 As shown in b1, between the first and second seats, from left to right, are arranged a first-seat speaker 7c, a first-seat microphone 9c, and a first-seat speaker 8c, which transmits sound towards the standard right ear position of the user of the first seat. In front of them, with respect to the left and right direction, between the first and second seats, from left to right, are arranged a second-seat speaker 7d, a second-seat microphone 9d, and a second-seat speaker 8d, which transmits sound towards the standard right ear position of the user of the second seat.

[0106] Furthermore, in this case, such as Figure 6As shown in b2, using the first-seat left learning microphone 60g positioned at the standard left ear position of the first-seat user, the first-seat right learning microphone 60h positioned at the standard right ear position of the first-seat user, the second-seat left learning microphone 60j positioned at the standard left ear position of the second-seat user, and the second-seat right learning microphone 60h positioned at the standard right ear position of the second-seat user; as the transfer function H1(z) of the first-seat auxiliary filter 34 of the first-seat noise control device 3 of the first group, the transfer function H1(z) corrected by the subtraction of the first-seat subtractor 35 is obtained for the difference between the output of microphone 9c and the output when microphone 9c is in the position of the first-seat right learning microphone 60h; as the transfer function H1(z) of the first-seat auxiliary filter 34 of the first-seat noise control device 3 of the second group; (z), calculate the transfer function H1(z) of the difference between the output of microphone 9d and the output when microphone 9d is in the position of the left learning microphone 60g (first seat), using the subtraction correction of the first seat subtractor 35; calculate the transfer function H2(z) of the second auxiliary filter 44 of the second noise control device 4 (first group), calculate the transfer function H2(z) of the difference between the output of microphone 9c and the output when microphone 9c is in the position of the left learning microphone 60j (second seat), using the subtraction correction of the second seat subtractor 45; calculate the transfer function H2(z) of the second auxiliary filter 44 of the second noise control device 4 (second group), calculate the transfer function H2(z) of the difference between the output of microphone 9d and the output when microphone 9d is in the position of the right learning microphone 60k (second seat), using the subtraction correction of the second seat subtractor 45.

[0107] Furthermore, this embodiment can also be extended to eliminate the sound from the audio sources of other seats when the audio source of each seat is multi-channel.

Claims

1. An active noise control system, characterized in that, The environment in which the first tone of the sound is output as the first sound source to the user seated in the first seat, and the second tone of the sound is output as the second sound source to the user seated in the second seat, is applied. The above-mentioned active noise control system has the following features: First speaker; Second speaker; microphone; A first noise control device outputs a first cancellation tone from the first loudspeaker, the first cancellation tone serving as a sound to cancel the second tone for a user seated in the first seat; and The second noise control device outputs a second cancellation sound from the second speaker, the second cancellation sound serving as a sound to cancel the first sound for the user seated in the second seat; The aforementioned first noise control device includes: The first auxiliary filter takes the second tone mentioned above as input; The first correction unit uses the output of the first auxiliary filter to correct the output of the microphone and outputs it as a first error signal; and The first adaptive filter takes the second tone mentioned above as input, and uses the first error signal mentioned above as error to perform an adaptive action to update its own transfer function, thereby generating the first canceled tone mentioned above. The first auxiliary filter is provided with a transfer function that is predetermined as a transfer function, such that the correction of the first correction unit performed by using the output of the first auxiliary filter is corrected so that the component of the second tone contained in the output of the microphone is corrected to the component of the second tone contained in the sound transmitted to the first elimination position, the first elimination position being a position that can be the listening position of the user sitting in the first seat. The aforementioned second noise control device includes: The second auxiliary filter takes the first tone mentioned above as its input. The second correction unit uses the output of the second auxiliary filter to correct the output of the microphone and outputs it as a second error signal; and The second adaptive filter takes the first tone as input and uses the second error signal as error to perform an adaptive action to update its own transfer function, thereby generating the second canceled tone. The second auxiliary filter is provided with a transfer function that is predetermined as a transfer function, such that the correction of the second correction unit performed by using the output of the second auxiliary filter is such that the component of the first tone contained in the output of the microphone is corrected to the component of the first tone contained in the sound transmitted to the second cancellation position, which is a position that can be the listening position of the user sitting in the second seat.

2. The active noise control system as described in claim 1, characterized in that, The microphone is positioned between the first speaker and the second speaker, with respect to the specified direction from the first seat to the second seat.

3. The active noise control system as described in claim 1, characterized in that, The direction from the first seat to the second seat is defined as the direction, and in relation to this defined direction, the first speaker, the microphone, and the second speaker are arranged between the listening position of the user seated in the first seat and the listening position of the user seated in the second seat. The microphone is positioned between the first speaker and the second speaker, according to the aforementioned specified orientation. The first tone is output from the first speaker toward the user seated in the first seat, and the second tone is output from the second speaker toward the user seated in the second seat.

4. The active noise control system as described in claim 3, characterized in that, The second seat mentioned above is the seat behind the first seat mentioned above, which is arranged in a front-back direction. The aforementioned first speaker, the aforementioned microphone, and the aforementioned second speaker are located at the aforementioned first seat.

5. The active noise control system as described in claim 4, characterized in that, The first speaker and the microphone are located in the headrest of the first seat, and the second speaker is located in the headrest or seat back of the first seat.

6. The active noise control system as described in claim 2, characterized in that, The second seat mentioned above is the seat behind the first seat mentioned above, which is arranged in a front-back direction. The aforementioned first speaker, the aforementioned microphone, and the aforementioned second speaker are located at the aforementioned first seat.

7. The active noise control system as described in claim 6, characterized in that, The first speaker and the microphone are located in the headrest of the first seat, and the second speaker is located in the headrest or seat back of the first seat.

8. The active noise control system as described in claim 1, characterized in that, The second seat mentioned above is the seat behind the first seat mentioned above, which is arranged in a front-back direction. The aforementioned first speaker, the aforementioned microphone, and the aforementioned second speaker are located at the aforementioned first seat.

9. The active noise control system as described in claim 8, characterized in that, The first speaker and the microphone are located in the headrest of the first seat, and the second speaker is located in the headrest or seat back of the first seat.

10. The active noise control system as described in claim 3, characterized in that, The second seat mentioned above is arranged in the left-right direction with the first seat mentioned above.

11. The active noise control system as described in claim 10, characterized in that, At least one of the aforementioned first speaker, microphone, and second speaker is disposed in the interior ceiling of the vehicle.

12. The active noise control system as described in claim 2, characterized in that, The second seat mentioned above is arranged in the left-right direction with the first seat mentioned above.

13. The active noise control system as described in claim 12, characterized in that, At least one of the aforementioned first speaker, microphone, and second speaker is disposed in the interior ceiling of the vehicle.

14. The active noise control system as described in claim 3, characterized in that, The second seat mentioned above is the seat behind the first seat mentioned above, which is arranged in a front-back direction. The first elimination position is the standard sound listening position of the user seated in the first seat, and the second elimination position is a position that is forward of the standard sound listening position of the user seated in the second seat and backward of the first seat.

Images