Signal processing device and signal processing method

Abstract

Provided are a signal processing device and a signal processing method that can suppress mixed sound such as sound emitted by a non-target speaker that is mixed into a target sound and prevent the target sound from being suppressed. The device comprises: a first acquisition unit (15) that acquires a first signal output from a first microphone (11); a second acquisition unit (16) that acquires a second signal output from a second microphone (12) that is arranged at a position different from the first microphone (11); a delay unit (4a) that delays the second signal; a mixed sound estimation unit (2) that estimates noise mixed into the first signal based on the second signal delayed by the delay unit (4a); and an elimination unit (3) that eliminates the noise estimated by the mixed sound estimation unit (2) from the first signal.

Description

Technical Field

[0001] The present disclosure relates to a signal processing device and a signal processing method. Background Art

[0002] As an in-vehicle device, a sound pickup device is often installed mainly at a driver's seat or the like for the purpose of acquiring the voice of a driver or the like in a vehicle. As a result, the driver or the like can perform voice-based operations when using an infotainment system or the like. For example, Patent Document 1 discloses an in-vehicle sound pickup device and a sound pickup method that can estimate and suppress the sound other than the driver or the like mixed into the target sound or the like, i.e., the noise.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: (Japanese) Patent Publication No. 2017-083600 Summary of the invention

[0006] However, in the technique disclosed in Patent Document 1, if a part of the target sound is eliminated, the target sound may be suppressed.

[0007] An object of the present disclosure is to suppress noise mixed into a target sound and prevent the target sound from being suppressed.

[0008] According to the signal processing device and signal processing method involved in the present disclosure, there are: a first acquisition unit, which acquires a first signal output from a first microphone; a second acquisition unit, which acquires a second signal output from a second microphone arranged at a position different from that of the first microphone; a delay unit, which delays the second signal; a mixed sound estimation unit, which estimates the noise mixed into the first signal based on the second signal delayed by the delay unit; and an elimination unit, which eliminates the noise estimated by the mixed sound estimation unit from the first signal.

[0009] The signal processing device and the signal processing method according to the present disclosure can suppress mixed sound such as non-target sound mixed into the target sound and prevent the target sound from being suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural diagram of a signal processing device in an embodiment of the present disclosure.

[0011] Figure 2 This is a flowchart showing the operation of the signal processing device in the embodiment of the present disclosure.

[0012] Figure 3 This is a diagram showing frequency characteristics of a signal representing the driver's voice acquired from the microphone 11 provided at the driver's seat before and after processing by the canceling unit when the delay unit delays the signal by 0 msec in the embodiment of the present disclosure.

[0013] Figure 4 The graph shows frequency characteristics of a signal representing the driver's voice acquired from the microphone 11 provided at the driver's seat before and after processing by the canceling unit when the delay unit delays the signal by 2 msec in the embodiment of the present disclosure.

[0014] Figure 5 The diagram shows frequency characteristics of a signal representing the driver's voice acquired from the microphone 11 provided at the driver's seat before and after processing by the canceling unit when the signal is delayed by 6 msec in the delay unit in the embodiment of the present disclosure.

[0015] Figure 6 The diagram shows frequency characteristics of a signal representing the voice of a passenger in the passenger seat acquired from the microphone 11 provided at the driver's seat before and after processing by the canceling unit in the embodiment of the present disclosure when the signal is delayed by 0 msec in the delay unit.

[0016] Figure 7 The diagram shows frequency characteristics of a signal representing the voice of a passenger in the passenger seat acquired from the microphone 11 provided at the driver's seat before and after processing by the canceling unit in the embodiment of the present disclosure when the signal is delayed by 2 msec in the delay unit.

[0017] Figure 8 The diagram shows frequency characteristics of a signal representing the voice of a passenger in the passenger seat acquired from the microphone 11 provided at the driver's seat before and after processing by the canceling unit in the embodiment of the present disclosure when the signal is delayed by 6 msec in the delay unit.

[0018] Fig. 9 This is a diagram of a translation system to which a signal processing system is applied in a modification example of the present disclosure.

[0019] Description of symbols

[0020] 1 Signal processing device

[0021] 2 Mixed sound estimation unit

[0022] 2a, 2b, 2c, 22 Adaptive filter

[0023] 3. 23 Elimination Department

[0024] 4a, 4b, 4c, 24 Delay section

[0025] 11, 12, 13, 14, 21a, 21b Microphones

[0026] 15, 25 First Acquisition

[0027] 16, 26 Second Acquisition

[0028] 17 Third Acquisition

[0029] 18 The fourth acquisition

[0030] 20 Translation System

[0031] 30a, 30b Characters

[0032] Line 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111 DETAILED DESCRIPTION

[0033] (Knowledge and insights that form the basis of this disclosure)

[0034] In the past, in order to estimate noise from a target sound, a method has been used in which a signal obtained from a microphone located at a position far from the microphone that obtains the target sound is used to estimate the noise mixed into the microphone that obtains the target sound, and to suppress the noise mixed into the target sound. For example, in the case where the driver's voice is to be obtained from a microphone set at a driver's seat, it is necessary to determine the voice of the passengers in the seats other than the driver's seat contained in the sound obtained by the microphone set at the driver's seat. Therefore, the voice of the passengers in the seats other than the driver's seat mixed into the sound obtained from the microphone set at the driver's seat is determined using the sounds obtained from the microphones set at the driver's seat. Among them, in order to use this method, it is necessary to control the operation of the sound receiving device such as the microphone set at each seat in coordination with the timing of the utterance of each passenger. However, it is difficult to determine whether the passengers in each seat are uttering a sound. In the case where the control is performed with an erroneous judgment as to whether the passengers in each seat are uttering a sound, there is a problem of suppressing the target sound. Furthermore, if control is performed with an erroneous judgment as to whether or not a passenger in each seat is speaking, there is also a problem that the performance of suppressing noise such as voices of other passengers mixed into the target voice is degraded.

[0035] Therefore, the signal processing device involved in one method of the present invention may also include: a first acquisition unit, which acquires a first signal outputted from a first microphone; a second acquisition unit, which acquires a second signal outputted from a second microphone arranged at a position different from that of the first microphone; a delay unit, which delays the second signal; a mixed sound estimation unit, which estimates the noise mixed into the first signal based on the second signal delayed by the delay unit; and an elimination unit, which eliminates the noise estimated by the mixed sound estimation unit from the first signal.

[0036] Thus, the signal processing device according to one aspect of the present disclosure can suppress the signal representing the sound as noise mixed into the target sound without suppressing the signal representing the target sound. Therefore, the signal processing device according to one aspect of the present disclosure can more accurately identify the target sound.

[0037] Furthermore, for example, the delay unit may delay the second signal by a time corresponding amount determined based on the positional relationship between the first microphone and the second microphone.

[0038] Thus, the signal processing device involved in one aspect of the present disclosure can prevent the second signal representing noise from reaching the elimination unit later than the first signal representing the target sound. Therefore, the signal processing device involved in one aspect of the present disclosure can use the second signal that has reached the elimination unit to process the first signal.

[0039] Furthermore, for example, the delay unit may delay the second signal based on a frequency component included in the second signal.

[0040] Thus, the signal processing device according to one aspect of the present disclosure can set a more appropriate delay time for the second signal representing noise. Therefore, the signal processing device according to one aspect of the present disclosure can more effectively suppress noise mixed in the first signal representing the target sound.

[0041] In addition, a signal processing method involved in one embodiment of the present invention may include: a first acquisition step of acquiring a first signal outputted from a first microphone; a second acquisition step of acquiring a second signal outputted from a second microphone arranged at a position different from that of the first microphone; a delay step of delaying the second signal; a mixed sound estimation step of estimating noise mixed into the first signal based on the second signal delayed by the delay step; and an elimination step of eliminating the noise estimated in the mixed sound estimation step from the first signal.

[0042] Thus, the signal processing method according to one aspect of the present disclosure can suppress the signal representing the sound as noise mixed into the target sound, and does not suppress the signal representing the target sound. Therefore, the signal processing device according to one aspect of the present disclosure can more accurately identify the target sound.

[0043] (Implementation Method)

[0044] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0045] Figure 1 The signal processing device 1 in the embodiment of the present disclosure is composed of a microphone 11, a microphone 12, a microphone 13, a microphone 14, a first acquisition unit 15, a second acquisition unit 16, a third acquisition unit 17, a fourth acquisition unit 18, a delay unit 4a, a delay unit 4b, a delay unit 4c, a mixed sound estimation unit 2 including an adaptive filter 2a, an adaptive filter 2b, and an adaptive filter 2c, and an elimination unit 3.

[0046] Microphones 11, 12, 13, and 14 acquire sounds and convert them into signals. The microphones may be moving coil microphones or ribbon microphones. In addition, the microphones may be condenser microphones or laser optical microphones.

[0047] The first acquisition unit 15 is electrically connected to the microphone 11 by wire or wirelessly. The first acquisition unit 15 receives a signal obtained by converting the sound acquired by the microphone 11 from the microphone 11. The first acquisition unit 15 does not include a delay unit.

[0048] The second acquisition unit 16 is electrically connected to the microphone 12 in a wired or wireless manner. The second acquisition unit 16 receives a signal obtained by converting the sound acquired by the microphone 12 from the microphone 12 .

[0049] The third acquisition unit 17 is electrically connected to the microphone 13 in a wired or wireless manner. The third acquisition unit 17 receives a signal obtained by converting the sound acquired by the microphone 13 from the microphone 13 .

[0050] The fourth acquisition unit 18 is electrically connected to the microphone 14 in a wired or wireless manner. The fourth acquisition unit 18 receives a signal obtained by converting the sound acquired by the microphone 14 from the microphone 14 .

[0051] The first acquisition unit 15, the second acquisition unit 16, the third acquisition unit 17, the fourth acquisition unit 18, the delay unit 4a, the delay unit 4b, the delay unit 4c, the mixed sound estimation unit 2 including the adaptive filter 2a, the adaptive filter 2b, and the adaptive filter 2c, and the elimination unit 3 are implemented by a processor and a memory. The functions of the processor and the memory may also utilize functions provided by cloud computing. In addition, the first acquisition unit 15, the second acquisition unit 16, the third acquisition unit 17, the fourth acquisition unit 18, the adaptive filter 2a, the adaptive filter 2b, and the adaptive filter 2c may also be implemented by dedicated circuits, respectively.

[0052] The delay unit 4a is electrically connected to the second acquisition unit 16, the delay unit 4b is electrically connected to the third acquisition unit 17, and the delay unit 4c is electrically connected to the fourth acquisition unit 18 by wire or wireless. The delay unit 4a, the delay unit 4b, and the delay unit 4c receive the second signal, the third signal, and the fourth signal respectively acquired by the second acquisition unit 16, the third acquisition unit 17, and the fourth acquisition unit 18, and delay the received signals for a predetermined time. Here, delaying the signal means that the signal received by the delay unit 4a, the delay unit 4b, and the delay unit 4c is sent to the mixed sound estimation unit 2 after a certain time has passed. In addition, for example, the delay unit 4a, the delay unit 4b, and the delay unit 4c are a memory group formed by stacking a plurality of continuously connected memories for delaying the signal for a predetermined time. In order to delay the signal, the memory group may output the acquired signal in a first-in-first-out (FIFO) manner. For example, the delay units 4a, 4b, and 4c output signals for a time equal to or shorter than the value obtained by dividing the distances between the microphones 11, 12, 13, and 14 by the speed of sound.

[0053] The mixed sound estimation unit 2 includes an adaptive filter 2a, an adaptive filter 2b, and an adaptive filter 2c. The mixed sound estimation unit 2 is electrically connected to the delay unit 4a, the delay unit 4b, and the delay unit 4c in a wired or wireless manner. The mixed sound estimation unit 2 receives the second signal, the third signal, and the fourth signal delayed by the delay unit 4a, the delay unit 4b, and the delay unit 4c. The mixed sound estimation unit 2 estimates the noise mixed in the first signal acquired by the first acquisition unit 15 based on the second signal, the third signal, and the fourth signal.

[0054] Specifically, the mixed-sound estimation unit 2 uses a predetermined adaptive algorithm to correct the filter coefficients of the adaptive filters 2a, 2b, and 2c so that the signal SO (an example of the output signal) output from the elimination unit 3 becomes uncorrelated or independent from the inputs of the adaptive filters 2a, 2b, and 2c. The signal SO is a signal obtained by subtracting the mixed-sound signal S2' from the signal S1 (an example of the first signal) obtained from the microphone 11. Therefore, if the filter coefficients of the adaptive filter 2a are corrected so that the signal SO becomes uncorrelated or independent from the input of the adaptive filter 2a, the signal output from the adaptive filter 2a indicates the mixed-sound signal S2' which is the sound after the sound emitted by the passenger P2 contained in the signal S1 is mixed into the sound emitted by the passenger P1.

[0055] In addition, the mixed sound estimation unit 2 may perform the correction process of the filter coefficient periodically, or may perform the correction process every time the microphones 12, 13, and 14 obtain a signal of a certain level or above. Here, as the predetermined adaptive algorithm, an LMS (least mean square) algorithm or an ICA (independent component analysis) algorithm may be used.

[0056] Adaptive filter 2a, adaptive filter 2b and adaptive filter 2c take out required signal from received signal through mathematical filter with variable coefficient. Specifically, as mentioned above, adaptive filter 2a, adaptive filter 2b and adaptive filter 2c can calculate new coefficient by calculation at any time, and change the coefficient used for filter. In the calculation of coefficient, dynamic nonlinear feedback control etc. can be used for feeding back the output of adaptive filter 2a, adaptive filter 2b and adaptive filter 2c respectively. In addition, adaptive filter 2a, adaptive filter 2b and adaptive filter 2c can change the size (gain) of the output of received signal. As adaptive filter, LMS filter etc. can be adopted.

[0057] The canceller 3 is electrically connected to the first acquisition unit 15 and the mixed-sound estimation unit 2 by wire or wirelessly. The canceller 3 suppresses the noise estimated by the mixed-sound estimation unit 2 in the first signal acquired by the first acquisition unit 15 .

[0058] For example, in the signal processing device 1, a microphone 11 may be provided at the driver's seat of the car, a microphone 12 may be provided at the front passenger seat of the car, and a microphone 13 and a microphone 14 may be provided at the rear seat of the car. In this case, the signal processing device 1 operates to suppress noise from the voice of the passenger (driver) at the driver's seat of the car. In order to suppress noise from the voice of the passenger in the seat other than the driver's seat of the car, a signal processing system symmetrical to the above-mentioned structural elements may be installed in the car. For example, in order to suppress noise from the voice of the passenger in the front passenger seat of the car, a microphone 11 may be provided at the front passenger seat of the car, a microphone 12 may be provided at the driver's seat of the car, and a microphone 13 and a microphone 14 may be provided at the rear seat of the car. In addition, for example, in order to suppress noise from the voice of the passenger in the rear seat on the left side of the car, a microphone 11 may be provided at the rear seat on the left side of the car, a microphone 12 may be provided at the driver's seat of the car, a microphone 13 may be provided at the front passenger seat of the car, and a microphone 14 may be provided at the rear seat on the right side of the car. Furthermore, for example, in order to suppress noise from the voice of the passenger in the right rear seat of the car, a microphone 11 may be provided in the right rear seat of the car, a microphone 12 may be provided in the driver's seat of the car, a microphone 13 may be provided in the passenger seat of the car, and a microphone 14 may be provided in the left rear seat of the car. Furthermore, a plurality of these symmetrical signal processing systems may be provided.

[0059] The connection relationship between the microphone 11, the microphone 12, the microphone 13, and the microphone 14 and the other structural elements of the signal processing device 1 is the same as described above. In addition, the installation locations of the microphones 11, the microphone 12, the microphone 13, and the microphone 14 are not limited to the locations shown above. In addition, the number of seats in the car where the microphones are installed is not limited to four. More than four microphones may be installed at more than four locations. For example, it may be six seats in a three-row passenger car, or the number of locations may be more than six. In addition, the number of locations where the microphones are installed may be less than three.

[0060] Furthermore, each of the structural elements described here may be provided in plurality in the signal processing device 1 .

[0061] Figure 2 1 is a flowchart showing the operation of the signal processing device in the embodiment of the present disclosure. In the following, the flow of the entire system is described using the flowchart.

[0062] First, in the signal processing device 1, the first acquisition unit 15 and the second acquisition unit 16 acquire the first signal and the second signal from the microphone 11 and the microphone 12, respectively (step S101). At this time, the third acquisition unit 17 and the fourth acquisition unit 18 may acquire the third signal and the fourth signal from the microphone 13 and the microphone 14, respectively.

[0063] Next, in the signal processing device 1, the delay unit 4a delays the second signal received from the second acquisition unit 16 by a predetermined time (step S102). At this time, the delay units 4b and 4c may delay the third signal received from the third acquisition unit 17 and the fourth signal received from the fourth acquisition unit 18 by a predetermined time.

[0064] The time for delaying the second signal, the third signal, and the fourth signal by the delay unit 4a, the delay unit 4b, and the delay unit 4c may be all the same, or different. The time for delaying the second signal, the third signal, and the fourth signal by the delay unit 4a, the delay unit 4b, and the delay unit 4c may also be determined by the positional relationship between the microphone 11 and the microphones 12, 13, and 14. Here, the positional relationship is, for example, the distance from the microphone 11. For example, the longer the distance from the microphone 11, the longer the signal delay time.

[0065] In addition, the time for delaying the second signal, the third signal and the fourth signal by the delay unit 4a, the delay unit 4b and the delay unit 4c can also be determined individually according to the respective frequencies of the second signal, the third signal and the fourth signal. For example, the delay unit 4a determines the frequency of the second signal by frequency analysis. And the delay unit 4a can also determine the time for delaying the signal based on a table prepared in advance that determines the delay time corresponding to the frequency. In addition, the delay unit 4a can also determine the time for delaying the signal according to the frequency component in the same signal. In a low-frequency signal, due to the long wavelength, the delay of the signal is difficult to work effectively. For example, it has been determined experimentally that if the time for delaying the low-frequency signal is set to be longer than a certain time, the degree of suppressing the first signal is reduced. Therefore, for example, the time for delaying the signal of the low-frequency component can also be set to be longer than a certain time, and the time for delaying the signal of the high-frequency component can be set to be shorter than a certain time.

[0066] Furthermore, the time by which the delay units 4 a , 4 b , and 4 c delay the second signal, the third signal, and the fourth signal may be determined according to the temperature of the vehicle interior or the like.

[0067] The time for delaying the second signal, the third signal, and the fourth signal by the delay unit 4a, the delay unit 4b, and the delay unit 4c is set so as not to exceed the time taken for the sound to travel between the microphone 11, the microphone 12, the microphone 13, and the microphone 14. For example, when the distance between the microphone 11 and the microphone 12 is 1 m, and the time taken for the sound to travel between the microphone 11 and the microphone 12 is 3 msec, the delay unit 4a sets a delay time of less than 3 msec for the second signal.

[0068] Next, in the signal processing device 1, the mixed sound estimation unit 2 estimates the noise mixed in the first signal obtained by the first acquisition unit 15 based on the second signal delayed by the delay unit 4a (step S103). At this time, the mixed sound estimation unit 2 may also estimate the noise mixed in the first signal obtained by the first acquisition unit 15 based on the third signal and the fourth signal delayed by the delay units 4b and 4c.

[0069] Then, in the signal processing device 1, the canceling unit 3 suppresses the noise estimated by the mixed sound estimating unit 2 from the first signal (step S104).

[0070] Next, use Figures 3 to 8 , the situation of the signal processed in the signal processing device 1 is explained.

[0071] In the signal processing device 1, by delaying the signals acquired by the second acquisition unit 16, the third acquisition unit 17, and the fourth acquisition unit 18 by an appropriate time, it is possible to prevent the signal indicating the target sound included in the signal indicating the sound etc. acquired from the second acquisition unit 16, the third acquisition unit 17, and the fourth acquisition unit 18 from being estimated as noise. The signal indicating the target sound included in the signal indicating the sound etc. acquired by the second acquisition unit 16, the third acquisition unit 17, and the fourth acquisition unit 18 reaches the elimination unit 3 later than the signal indicating the target sound acquired from the first acquisition unit 15. Therefore, the elimination unit 3 does not suppress the target sound acquired by the first acquisition unit 15 based on the signal indicating the target sound included in the signal indicating the target sound acquired from the second acquisition unit 16, the third acquisition unit 17, and the fourth acquisition unit 18.

[0072] Figure 3 1 is a diagram showing frequency characteristics of a signal representing the voice of the driver obtained from the microphone 11 provided at the driver's seat before and after processing by the elimination unit when the delay unit delays the signal by 0 msec in an embodiment of the present disclosure. Line 100 is the frequency characteristic of the first signal when the delay unit 4a delays the second signal by 0 msec without performing the processing by the elimination unit 3. Line 101 is the frequency characteristic of the first signal when the delay unit 4a delays the second signal by 0 msec and performs the processing by the elimination unit 3. Spanning between about 100 Hz and about 10000 Hz, line 101 shows a value lower than that of line 100. That is, if the elimination unit 3 is operated when a delay of 0 msec is applied to the second signal in the delay unit 4a, the elimination unit 3 suppresses the first signal. This is because the second signal contains a signal with the same waveform as the first signal, and the first signal is suppressed by eliminating the noise estimated using the second signal.

[0073] For example, in order to suppress noise from the sound acquired by the microphone 11 installed in the driver's seat, the sound acquired by the microphone 12 installed in the passenger seat is considered to be used. The sound emitted by the driver is mixed into the sound acquired by the microphone 12 installed in the passenger seat due to reflection in the vehicle cabin, etc. Based on the driver's voice mixed into the sound acquired by the microphone 12 installed in the passenger seat, the driver's voice included in the sound acquired by the microphone 11 installed in the driver's seat is suppressed.

[0074] Figure 4 1 is a graph showing frequency characteristics of a signal representing the driver's voice obtained from a microphone 11 installed in a driver's seat before and after processing by an elimination unit when the delay unit delays the signal by 2 msec in an embodiment of the present disclosure. Line 102 is a frequency characteristic of the first signal without processing by the elimination unit 3 when the delay unit 4a delays the second signal by 2 msec. Line 103 is a frequency characteristic of the first signal after processing by the adaptive filter 2a when the delay unit 4a delays the second signal by 2 msec. Spanning from about 100 Hz to about 10,000 Hz, line 102 shows a value lower than line 103, but is similar to line 103. Figure 3 The difference between the line 100 and the line 101 shown is smaller.

[0075] That is, if the canceling unit 3 is operated while the second signal is delayed by 2 msec in the delay unit 4a, the amount of the first signal suppressed by the canceling unit 3 is reduced. This is because the signal with the same waveform as the first signal included in the second signal is reduced by delaying the second signal by 2 msec. Therefore, by eliminating the noise estimated by using the second signal, the first signal is suppressed, but the noise is not as good as the first signal. Figure 3 is reduced compared to the situation shown.

[0076] Here, for a delay of 2 msec, the speed of sound in the air is about 340 m / sec, so the distance traveled by the sound is about 60 cm to about 70 cm. That is, when the microphone 11 and the microphone 12 are arranged about 60 cm to about 70 cm apart, the time taken for the driver's voice to reach the microphone 12 is about 2 msec.

[0077] For example, in order to suppress noise from the sound obtained by the microphone 11 installed in the driver's seat, consider the case where the sound obtained by the microphone 12 installed in the passenger seat is used. The sound emitted by the driver is mixed into the sound obtained by the microphone 12 installed in the passenger seat through reflection in the vehicle cabin, etc. However, by delaying the signal representing the sound obtained by the microphone 12 installed in the passenger seat by 2 msec, the degree of suppressing the driver's voice included in the sound obtained by the microphone 11 installed in the driver's seat based on the driver's voice included in the sound obtained by the microphone 12 installed in the passenger seat is reduced. In order for the cancellation unit 3 to suppress the driver's voice included in the sound obtained by the microphone 11 installed in the driver's seat based on the driver's voice included in the sound obtained by the microphone 12 installed in the passenger seat, the sound obtained by the microphone 12 installed in the passenger seat must reach the cancellation unit 3 before the sound obtained by the microphone 11 installed in the driver's seat. However, by delaying the sound acquired by the microphone 12 installed at the passenger seat, the sound acquired by the microphone 12 installed at the passenger seat cannot reach the canceling unit 3 before the sound acquired by the microphone 11 installed at the driver's seat. Therefore, the canceling unit 3 reduces the degree to which the driver's voice included in the sound acquired by the microphone 11 installed at the driver's seat is suppressed based on the driver's voice included in the sound acquired by the microphone 12 installed at the passenger seat.

[0078] Figure 5 1 is a graph showing frequency characteristics of a signal representing the driver's voice obtained from a microphone 11 installed in a driver's seat before and after processing by an elimination unit when the signal is delayed by 6 msec in a delay unit in an embodiment of the present disclosure. Line 104 is a frequency characteristic of the first signal when the first signal is delayed by 6 msec without performing the processing by the elimination unit 3. Line 105 is a frequency characteristic of the first signal when the first signal is delayed by 6 sec and the processing by the adaptive filter 2a is performed. Spanning from about 100 Hz to about 10000 Hz, line 104 shows a value lower than line 105, but is similar to line 105. Figure 4 The difference between the line 104 and the line 105 is smaller than the difference between the line 102 and the line 103 shown.

[0079] That is, if the canceling unit 3 is operated while the second signal is delayed by 6 msec in the delay unit 4a, the amount of the first signal suppressed by the canceling unit 3 is reduced. This is because the signal with the same waveform as the first signal included in the second signal is reduced by delaying the second signal by 6 msec. Therefore, by eliminating the noise estimated by using the second signal, the first signal is suppressed, but the noise is not as good as the first signal. Figure 4 The difference between the lines 102 and 103 is shown to be reduced.

[0080] For example, in order to suppress noise from the sound acquired by the microphone 11 installed in the driver's seat, the sound acquired by the microphone 12 installed in the passenger seat is considered. The sound emitted by the driver is mixed into the sound acquired by the microphone 12 installed in the passenger seat due to reflection in the vehicle cabin, etc. However, by delaying the signal representing the sound acquired by the microphone 12 installed in the passenger seat by 6 msec, the degree of suppressing the driver's voice included in the sound acquired by the microphone 11 installed in the driver's seat based on the driver's voice included in the sound acquired by the microphone 12 installed in the passenger seat is further reduced compared to the case where the delay is 2 msec.

[0081] from Figure 3 , Figure 4 and Figure 5 It can be seen that the degree to which the signal representing the target sound is suppressed is reduced by delaying the signal in the delay unit.

[0082] Figure 6 1 is a diagram showing the frequency characteristics of a signal representing the voice of a passenger in the passenger seat obtained from a microphone 11 disposed on the driver's seat before and after processing by an elimination unit in an embodiment of the present disclosure when the signal is delayed by 0 msec in the delay unit. Line 106 is the frequency characteristic of the first signal when the first signal is delayed by 0 msec without performing the processing by the elimination unit 3. Line 107 is the frequency characteristic of the first signal when the first signal is delayed by 0 msec after performing the processing by the adaptive filter 2a. Spanning between about 100 Hz and about 10,000 Hz, line 104 represents a value 20 dB lower than line 105. That is, the voice of the passenger in the passenger seat mixed into the microphone 11 disposed on the driver's seat is suppressed.

[0083] For example, in order to suppress noise from the sound acquired by the microphone 11 installed in the driver's seat, consider using the sound acquired by the microphone 12 installed in the passenger seat. The sound emitted by the passenger in the passenger seat is mixed into the sound acquired by the microphone 11 installed in the driver's seat directly or through reflection in the vehicle interior. The noise after the mixing is estimated by using the waveform of the signal of the sound acquired by the microphone 12 installed in the passenger seat, and the noise is removed from the sound acquired by the microphone 11 installed in the driver's seat. Figure 6 As shown in FIG. 1 , when the signal representing the sound acquired by the microphone 12 installed at the passenger seat is delayed by 0 msec, the sound acquired by the microphone 11 installed at the driver seat is suppressed by about 20 dB.

[0084] Figure 71 is a graph showing the frequency characteristics of a signal representing the voice of a passenger in the passenger seat obtained from a microphone 11 installed in the driver's seat before and after processing by an elimination unit in an embodiment of the present disclosure when the signal is delayed by 2 msec in the delay unit. Line 108 is the frequency characteristic of the first signal when the processing by the elimination unit 3 is not performed when the first signal is delayed by 2 msec. Line 109 is the frequency characteristic of the first signal when the processing by the adaptive filter 2a is performed when a delay of 2 msec is applied to the first signal. Spanning from about 100 Hz to about 10000 Hz, line 108 shows a value lower than that of line 109. However, compared with Figure 6 The amount of suppression of the first signal is shown compared to Figure 7 The amount of suppression of the first signal is shown to be reduced.

[0085] For example, in order to suppress noise from the sound acquired by the microphone 11 installed in the driver's seat, consider the case where the sound acquired by the microphone 12 installed in the passenger seat is used. As described above, the sound emitted by the passenger in the passenger seat is mixed into the sound acquired by the microphone 11 installed in the driver's seat directly or through reflection in the vehicle interior. The noise after the mixing is estimated by using the waveform of the signal of the sound acquired by the microphone 12 installed in the passenger seat, and the noise is removed from the sound acquired by the microphone 11 installed in the driver's seat. Figure 7 As shown, when the signal representing the sound acquired by the microphone 12 installed in the front passenger seat is delayed by 2 msec, the degree of suppressing the sound acquired by the microphone 11 installed in the driver's seat is reduced compared to the case where the signal representing the sound acquired by the microphone 12 installed in the front passenger seat is delayed by 0 msec. The voice of the passenger in the front passenger seat mixed in the sound acquired by the microphone 11 installed in the driver's seat is estimated as noise, and from the viewpoint of suppressing the sound acquired from the microphone 11 installed in the driver's seat, it is desirable not to delay the signal representing the sound acquired by the microphone 12 installed in the front passenger seat.

[0086] Figure 8 It is a graph showing the frequency characteristics of a signal representing the voice of a passenger in the passenger seat obtained from a microphone 11 installed in the driver's seat before and after processing by the elimination unit in an embodiment of the present disclosure when the signal is delayed by 6 msec in the delay unit. Line 110 is the frequency characteristic of the first signal when a delay of 6 msec is applied to the first signal without performing the processing by the elimination unit 3. Line 111 is the frequency characteristic of the first signal when the processing by the adaptive filter 2a is performed when the first signal is delayed by 6 msec. Spanning between about 100 Hz and about 10,000 Hz, line 110 shows a value lower than line 111. However, compared with Figure 7 The inhibition shown is compared to Figure 8 The amount of inhibition shown was reduced.

[0087] For example, in order to suppress noise from the sound acquired by the microphone 11 installed in the driver's seat, consider the case where the sound acquired by the microphone 12 installed in the passenger seat is used. As described above, the sound emitted by the passenger in the passenger seat is mixed into the sound acquired by the microphone 11 installed in the driver's seat directly or through reflection in the vehicle interior. The noise after the mixing is estimated by using the waveform of the signal of the sound acquired by the microphone 12 installed in the passenger seat, and the noise is removed from the sound acquired by the microphone 11 installed in the driver's seat. Figure 8 As shown, when the signal representing the sound acquired by the microphone 12 installed in the front passenger seat is delayed by 6 msec, the degree of suppressing the sound acquired by the microphone 11 installed in the driver's seat is reduced compared with the case where the signal representing the sound acquired by the microphone 12 installed in the front passenger seat is delayed by 0 msec and the case where the signal representing the sound acquired by the microphone 12 installed in the front passenger seat is delayed by 2 msec. The voice of the passenger in the front passenger seat mixed in the sound acquired by the microphone 11 installed in the driver's seat is estimated as noise. From the viewpoint of suppressing the noise acquired from the sound acquired by the microphone 11 installed in the driver's seat, it is desirable not to delay the signal representing the sound acquired by the microphone 12 installed in the front passenger seat.

[0088] like Figure 6 , Figure 7 and Figure 8 It is understood that the degree to which the signal representing the sound as noise is suppressed is reduced by delaying the signal in the delay unit 4a. Therefore, in order to suppress the signal representing the sound as noise, it is desirable that the signal is not delayed for more than a predetermined time in the delay unit 4a.

[0089] On the contrary, Figure 3 , Figure 4 and Figure 5 As shown, in order not to suppress the target sound, it is desirable to delay the signal for a predetermined time or longer. As described above, the signal delay time is set by the delay unit 4a, the delay unit 4b, and the delay unit 4c so as not to exceed the time taken for the sound to travel between the microphone 11, the microphone 12, the microphone 13, and the microphone 14.

[0090] The delay time of the signal set by the delay unit 4a, the delay unit 4b and the delay unit 4c can also be based on Figures 3 to 8 The trend of sound suppression in the signal processing device 1 shown is determined.

[0091] (Variation Example)

[0092] The signal processing device 1 described above can also be applied to a translation system 20 that recognizes the voice of a speaker, translates it into other languages, and outputs it. Fig. 9 FIG. 1 is a diagram of a translation system to which a signal processing system is applied in a modified example of the present disclosure. Fig. 9 As shown, the translation system 20 includes a microphone 21a, a microphone 21b, a first acquisition unit 25, a second acquisition unit 26, a delay unit 24 including an adaptive filter 22, and an elimination unit 23. The translation system 20 may further include an information processing unit that recognizes and translates the noise-suppressed sound, and an output unit that outputs the translation result.

[0093] The first acquisition unit 25 is electrically connected to the microphone 21a by wire or wirelessly. The first acquisition unit 25 acquires a first signal such as sound from the microphone 21a. The first acquisition unit 25 receives a signal obtained by converting the sound acquired by the microphone 21a from the microphone 21a.

[0094] The second acquisition unit 26 is electrically connected to the microphone 21b by wire or wirelessly. The second acquisition unit 26 acquires a second signal such as sound from the microphone 21b. The second acquisition unit 26 receives a signal obtained by converting the sound acquired by the microphone 21b from the microphone 21b.

[0095] The first acquisition unit 25, the second acquisition unit 26, the delay unit 24 including the adaptive filter 22, and the elimination unit 23 are implemented by a processor and a memory. The functions of the processor and the memory can also use functions provided by cloud computing. In addition, the first acquisition unit 25, the second acquisition unit 26, and the adaptive filter 22 can also be implemented by dedicated circuits.

[0096] The delay unit 24 is electrically connected to the second acquisition unit 26 in a wired or wireless manner. The delay unit 24 receives the fifth signal acquired by the second acquisition unit 26 and delays the received signal by a predetermined time.

[0097] The adaptive filter 22 is electrically connected to the delay unit 24 by wire or wirelessly. The adaptive filter 22 receives the fifth signal delayed by the delay unit 24. The adaptive filter 22 estimates the noise mixed in the fifth signal acquired by the first acquisition unit 25 based on the fifth signal.

[0098] The adaptive filter 22 extracts a desired signal from the received signal by using a mathematical filter with variable coefficients. The adaptive filter 22 can calculate new coefficients at any time and change the coefficients used for the filter.

[0099] The canceling unit 23 is electrically connected to the first acquisition unit 25 and the adaptive filter 22 by wire or wirelessly. The canceling unit 23 suppresses the noise estimated by the adaptive filter 22 from the fifth signal acquired by the first acquisition unit 25 .

[0100] The translation system 20 in the modified example of the present disclosure assumes that the person 30a and the person 30b are used in a face-to-face manner. In the translation system 20, the first acquisition unit 25 acquires the sound emitted by the person 30a through the microphone 21a. In addition, in the translation system 20, the second acquisition unit 26 acquires the sound emitted by the person 30b through the microphone 21b. The sound signal acquired by the second acquisition unit 26 is delayed for a certain time in the delay unit 24 and processed by the adaptive filter 22. In addition, the information of the noise estimated by the adaptive filter 22 reaches the elimination unit 23. The elimination unit 23 suppresses the noise estimated by the adaptive filter 22 from the sound signal acquired by the first acquisition unit 25.

[0101] The noise-suppressed sound signal is translated and the translation result is output. As described above, the translation system 20 can suppress noise such as the sound emitted by the character 30b from the sound emitted by the character 30a. In addition, the number of each structural element included in the translation system 20 can also be increased than that shown above. In the translation system 20 in the modified example of the present disclosure, it is assumed that two characters are used, but the number of people used is not limited to two people. The translation system 20 in the modified example of the present disclosure can also be a structure that can be used by more than three people.

[0102] In addition, these overall or specific methods can also be implemented through systems, methods, integrated circuits, computer programs, or computer-readable recording media such as CD-ROMs, or through any combination of systems, methods, integrated circuits, computer programs, and recording media.

[0103] The signal processing device 1 and the signal processing method are described above based on the implementation mode, but the signal processing system and the signal processing method are not limited to the present implementation mode. As long as it does not deviate from the purpose of the present disclosure, the method of applying various modifications thought of by those skilled in the art to the present implementation mode and the method of combining and constructing the structural elements in different implementation modes may also be included in the scope of one or more methods.

[0104] Industrial Availability

[0105] The present disclosure can be applied to a vehicle-mounted radio system or a translation system.

Claims

1. A signal processing device comprising: A first acquisition unit, which acquires a first signal outputted from a first microphone; a second acquisition unit that acquires a second signal output from a second microphone that is disposed at a position different from that of the first microphone; a delay unit, delaying the second signal; a mixed sound estimation unit that estimates noise mixed into the first signal based on the second signal delayed by the delay unit; and an eliminating unit that eliminates the noise estimated by the mixed sound estimating unit from the first signal, The delay unit delays a signal of a first frequency component included in the second signal by a first time, and delays a signal of a second frequency component included in the second signal by a second time. The signal of the second frequency component has a frequency lower than that of the first frequency component, and the second time is longer than the first time.

2. The signal processing device according to claim 1, The delay unit delays the second signal by a time corresponding amount determined based on the positional relationship between the first microphone and the second microphone.

3. A signal processing method, comprising: A first acquisition step of acquiring a first signal outputted from a first microphone; a second acquisition step of acquiring a second signal outputted from a second microphone disposed at a position different from that of the first microphone; A delay step, delaying the second signal; a mixed sound estimation step of estimating noise mixed into the first signal based on the second signal delayed by the delay step; as well as a removing step of removing the noise estimated in the mixed sound estimating step from the first signal, In the delay step, delaying a signal of a first frequency component contained in the second signal by a first time, and delaying a signal of a second frequency component contained in the second signal by a second time, The signal of the second frequency component has a frequency lower than that of the first frequency component, and the second time is longer than the first time.

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