JP2016180971A - Active noise suppression system and active noise suppression system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active noise suppression system capable of adequately achieving both of conversation assistance and active noise suppression within a closed space.SOLUTION: An active noise suppression system 11 for a vehicle includes: a first microphone 13A and first speaker 13B arranged in a front seat space 13; a second microphone 15A and second speaker 15B arranged in a rear seat space 15; and an active noise suppression device 17 for performing control to allow the first speaker 13B and the second speaker 15B to output canceling sound to suppress noise inside a cabin. The active noise suppression device 17 performs processing of: removing a sound component belonging to a frequency band related to the second canceling sound from sound collected by the first microphone 13A when generating first synthesis sound; and removing a sound component belonging to a frequency band related to the first canceling sound from sound collected by the second microphone 15A when generating second synthesis sound.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an active noise suppression system that assists conversation by actively suppressing noise in a closed space where periodic noise occurs, and an active noise suppression system for a vehicle.

  2. Description of the Related Art Conventionally, an in-vehicle acoustic device is known to assist smooth conversation in a closed space where periodic noise occurs, for example, in a vehicle interior (see Patent Document 1). The on-vehicle acoustic device according to Patent Document 1 drives a speaker disposed in the rear of the passenger compartment with a microphone disposed in front of the passenger compartment, and has a speaker disposed in the front of the passenger compartment with a microphone disposed in the rear of the passenger compartment. Driving to assist smooth conversation between the front and rear passengers.

  On the other hand, in order to suppress noise such as engine sound that enters the vehicle interior, active noise that actively suppresses vehicle interior noise is generated by generating a canceling sound having a phase opposite to the phase of the noise from the speaker. A suppression technique is also known (see Patent Document 2).

JP 2002-51392 A Japanese Patent Laid-Open No. 7-30994

  However, for example, when an application in which the conversation assistance technology in the closed space according to Patent Document 1 and the active noise suppression technology according to Patent Document 2 are simply combined is attempted, the speaker can hear the voice related to the conversation assistance and the active voice. A synthesized sound with a canceling sound related to noise suppression is output. Then, in the active noise suppression technology according to Patent Document 2, since control related to active noise suppression is performed based on the synthesized sound picked up by the microphone, this control operation may become unstable.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an active noise suppression system capable of accurately achieving both conversation assistance and active noise suppression in a closed space.

  In order to achieve the above object, the invention according to claim 1 is provided in a first space in a closed space and collects a sound generated in the first space; A second sound collecting unit that is provided in a second space that is distant from the first space in the closed space and collects sound generated in the second space; and a second sound collecting unit that is provided in the first space. A first sound output unit that outputs sound; a second sound output unit that is provided in the second space and outputs sound; and a canceling sound for suppressing noise in the closed space. An active noise suppression device that performs control to output from at least one of the first audio output unit and the second audio output unit, and an active noise suppression system that actively suppresses the noise, The active noise suppression device receives the noise and the voice collected by the first sound collection unit. A first speech synthesizing unit that generates a first synthesized speech obtained by synthesizing the speech collected by the second sound collecting unit with respect to the first canceling sound generated by illuminating, the noise and the noise A second synthesized voice is generated by synthesizing a voice collected by the first sound collecting section with a second canceling sound generated by referring to the voice collected by the second sound collecting section. A second speech synthesizer that controls the output of the first synthesized speech to the first speech output unit, while outputting the second synthesized speech to the second speech output unit. And generating the first and second synthesized voices from the voice collected by the first sound collection unit and the voice collected by the second sound collection unit in the closed space The main feature is to perform a process of removing a speech component belonging to a frequency band related to noise to be suppressed.

  According to the first aspect of the present invention, when the sound generated in the first space or the second space is synthesized with the canceling sound related to the noise, the sound collected by the first sound collecting unit and the first sound are collected. In order to perform processing to remove speech components belonging to the frequency band related to the noise to be suppressed in the closed space from the sound collected by the sound collecting unit 2, conversation assistance and active noise suppression in the closed space are performed. Can be achieved accurately.

  The invention according to claim 2 is the active noise suppression system according to claim 1, wherein the active noise suppression device includes the active noise suppression device, the first sound output unit, and the second sound. Obtained by an output unit, a transfer function obtaining unit that obtains an open-loop transfer function of an acoustic system including the first sound collecting unit and the second sound collecting unit, and the transfer function obtaining unit. And a setting unit for setting a gain coefficient at which the open-loop transfer function is 0 dB or less, and an error signal related to the sound collected by the first sound collecting unit and the second sound collecting unit. And a correction unit that performs correction by multiplying the gain coefficients set by the unit.

  An open loop transfer function of an acoustic system including the active noise suppression device, the first sound output unit and the second sound output unit, and the first sound collection unit and the second sound collection unit is 0 dB. If the frequency characteristic exceeds (1 times), a diverging loop is formed in the acoustic system, and the control operation related to active noise suppression becomes unstable, which may cause a howling phenomenon.

Therefore, in the invention according to claim 2, the active noise suppression device includes a transfer function acquisition unit that acquires an open loop transfer function of the acoustic system, and the open loop transfer function acquired by the transfer function acquisition unit is 0 dB or less. And a gain coefficient set by the setting unit for an error signal related to the sound collected by the first sound collection unit and the second sound collection unit, respectively. A configuration including a correction unit that performs correction for multiplication is employed.
According to the second aspect of the present invention, the correcting unit multiplies the error signal related to the sound collected by the first sound collecting unit and the second sound collecting unit by the set gain coefficient, respectively. In order to perform correction, stabilization of the control operation related to active noise suppression makes it possible to accurately achieve both conversation assistance and active noise suppression in a closed space while avoiding the occurrence of a howling phenomenon. it can.

  The invention according to claim 3 is the active noise suppression system according to claim 1 or 2, wherein the active noise suppression device includes the first sound output unit and the second sound output unit. As a sound output mode used when outputting sound from at least one of the above, the first synthesized sound is output to the first sound output unit while the second synthesized sound is output to the second sound output. The synthesized sound output mode to be output to the unit and the cancellation sound output mode to output the first or second cancellation sound from at least one of the first sound output unit and the second sound output unit can be switched. The active noise suppression device includes a reference signal generation unit that generates a reference signal based on at least a reference signal correlated with the noise, a reference signal generated by the reference signal generation unit, and the first convergence. Using the step size parameter set when adjusting the error signal related to the sound picked up by the sound collecting unit or the sound picked up by the second sound collecting unit and the coefficient update amount of the adaptive filter A filter coefficient update unit that updates the filter coefficient of the control signal, and a control signal generation unit that generates the control signal related to the first or second canceling sound by multiplying the reference signal by the filter coefficient of the adaptive filter. The step size parameter when the synthesized speech output mode is selected is set to a value smaller than that when the mute output mode is selected.

  For example, when the synthesized speech output mode is selected, the control operation related to active noise suppression may become unstable as compared with the case where the mute output mode is selected. This is because in the synthesized speech output mode, the filter coefficient of the adaptive filter is updated according to the sound collection results relating to the first and second synthesized speech (error signal).

Therefore, a smaller value is set for the step size parameter when the synthesized speech output mode is selected compared to when the cancellation sound output mode is selected.
According to the third aspect of the present invention, the control operation relating to the active noise suppression accompanying the filter coefficient update of the adaptive filter, regardless of which one of the synthesized voice output mode and the cancellation sound output mode is selected as the voice output mode. Stability can be ensured.

  The invention according to claim 4 is the active noise suppression system according to claim 3, wherein the active noise suppression device exceeds 0 as the gain coefficient when the synthesized speech output mode is selected. While the value less than 1 is set and the muting output mode is selected, the gain coefficient is set to 0, and the synthetic voice output mode or the muting output mode is changed to the other. The sound output mode is switched with a predetermined time constant.

In the invention according to claim 4, when the synthesized speech output mode is selected, a value less than 1 exceeding 0 is set as the gain coefficient. On the other hand, when the cancellation sound output mode is selected, the value 0 is set as the gain coefficient.
As a result, when the synthesized speech output mode is selected, a gain coefficient is obtained for the error signal related to the sound collected by the first sound collection unit or the sound collected by the second sound collection unit. As a result, a correction for multiplying a value less than 1 exceeding 0 is performed. In this case, the influence of the error signal can be suppressed.
On the other hand, when the cancellation sound output mode is selected, a gain coefficient is used for an error signal related to the sound collected by the first sound collection unit or the sound collected by the second sound collection unit. Correction for multiplying by the value 0 is performed. In this case, the influence of the error signal can be eliminated.
According to the invention of claim 4, since the switching of the voice output mode from one of the synthesized voice output mode or the cancellation sound output mode to the other is performed with a predetermined time constant, for example, the voice output mode Even when the gain coefficient is switched in accordance with the switching, the generation of abnormal noise when the audio output mode is switched instantaneously (without providing a predetermined time constant) can be suppressed.

  On the other hand, the invention according to claim 5 is provided in the front seat space in the vehicle interior and collects the sound generated in the front seat space, and in the rear seat space in the room. A second sound collecting unit for collecting sound generated in the rear seat space, a first sound output unit for outputting sound provided in the front seat space, and a sound provided in the rear seat space. And a second sound output unit that outputs noise and a canceling sound for suppressing noise in the room is output from at least one of the first sound output unit and the second sound output unit. An active noise suppression system for a vehicle that actively suppresses the noise, wherein the active noise suppression device includes the noise and the sound collected by the first sound collection unit. In response to the first canceling sound generated with reference to FIG. A first speech synthesizer that generates a first synthesized speech obtained by synthesizing the sound that has been sounded, and a second cancellation generated with reference to the noise and the speech collected by the second sound collection unit A second voice synthesis unit that generates a second synthesized voice obtained by synthesizing the voice collected by the first sound collection unit with respect to the sound, and the first synthesized voice is converted into the first synthesized voice. The first sound pickup is performed when generating the first and second synthesized voices by performing control to output the second synthesized voice to the second voice output unit while outputting to the voice output unit. The main process is to remove the sound component belonging to the frequency band related to the noise to be suppressed in the room from the sound collected by the unit and the sound collected by the second sound collecting unit. Features.

  According to the fifth aspect of the present invention, the sound collected by the first sound collection unit when the sound generated in the front seat space or the rear seat space in the vehicle interior is synthesized with the noise canceling sound. In addition, in order to perform processing for removing speech components belonging to the frequency band related to the noise to be suppressed in the room from the sound collected by the second sound collecting unit, the conversation assistance in the vehicle room and the active noise suppression are performed. Can be achieved accurately.

  According to the active noise suppression system of the present invention, it is possible to accurately achieve both conversation assistance and active noise suppression in a closed space by stabilizing the control operation related to active noise suppression.

It is a schematic block diagram showing the example which mounted the active noise suppression system which concerns on embodiment of this invention in the vehicle. 1 is a block diagram schematically illustrating an internal configuration of an active noise suppression device according to a first embodiment. It is a block diagram which represents roughly the internal structure of an ANC control part. It is a block diagram which represents roughly the internal structure of the active noise suppression apparatus which concerns on 2nd Embodiment.

Hereinafter, an active noise suppression system according to first and second embodiments of the present invention will be described in detail with reference to the drawings, taking an example of mounting the system on a vehicle.
In the following description of the first and second embodiments, in principle, components having a common function between the two are denoted by common reference numerals. However, although they have a common function, the branch number “−1” is assigned to the component unique to the first embodiment, the branch number “−2” is assigned to the component unique to the second embodiment, In principle, each shall be attached.
However, the active noise suppression systems according to the first and second embodiments are collectively referred to as the first and second embodiments using the reference numeral “11” excluding the branch numbers when each individual description is not required. Shall. The same applies to the active noise suppression devices according to the first and second embodiments.

[Outline of Active Noise Suppression System 11 for Vehicles According to an Embodiment of the Present Invention]
First, the outline | summary of the active noise suppression system 11 for vehicles which concerns on embodiment common to 1st and 2nd embodiment of this invention is demonstrated with reference to FIG. FIG. 1 is a schematic configuration diagram showing an example in which an active noise suppression system according to an embodiment of the present invention is mounted on a vehicle.

The vehicular active noise suppression system 11 according to the embodiment of the present invention has a function of accurately achieving both conversation assistance in the room of the vehicle V and active noise suppression.
In order to realize such a function, the vehicle active noise suppression system 11 is provided in a front seat space 13 in the interior of the vehicle V (hereinafter sometimes referred to as a vehicle interior) as shown in FIG. A first microphone 13 </ b> A that collects sound generated in the space 13, a second microphone 15 </ b> A that is provided in the rear seat space 15 in the vehicle interior and collects sound generated in the rear seat space 15, and the front seat space 13. The first speaker 13B that is provided and outputs sound, the second speaker 15B that is provided in the rear seat space 15 and outputs sound, and the canceling sound for suppressing noise in the vehicle interior are the first speaker 13B and the first speaker 13B. And an active noise suppression device 17 that performs control to output from at least one of the two speakers 15B.

  The front seat space 13 corresponds to the “first space” of the present invention, and the rear seat space 15 corresponds to the “second space” of the present invention. The first microphone 13A corresponds to the “first sound collection unit” of the present invention, and the second microphone 15A corresponds to the “second sound collection unit” of the present invention. The first speaker 13B corresponds to the “first audio output unit” of the present invention, and the second speaker 15B corresponds to the “second audio output unit” of the present invention.

  As shown in FIG. 1, an audio amplifier 19 that amplifies and outputs an input audio signal is connected to the active noise suppression device 17. A first speaker 13B and a second speaker 15B are connected to an output terminal (not shown) of the audio amplifier 19. The 1st speaker 13B and the 2nd speaker 15B play the role which suppresses the noise in a vehicle interior while transmitting the voice which concerns on the conversation in a vehicle interior from one side to the other.

  Further, as shown in FIG. 1, the active noise suppression device 17 includes an engine rotation speed sensor 23 and a synthesis mode selection switch 25 via a communication medium 21 such as a CAN (Controller Area Network). It is connected so that it can communicate.

  CAN is a multiplexed serial communication network generally used for information communication between in-vehicle devices, and has excellent data transfer speed and error detection capability. However, the information communication medium 21 used in the present invention is not limited to CAN. As the information communication medium 21 used in the present invention, for example, FlexRay (registered trademark) may be adopted.

  The engine rotation speed sensor 23 has a function of detecting the rotation speed of a reciprocating engine (not shown) mounted on the vehicle V. The engine speed information detected by the engine speed sensor 23 is sent to the active noise suppression device 17.

  The synthesis mode selection switch 25 is a switch provided in the passenger compartment and operated when the occupant selects the audio output mode. The synthesis mode selection information selected by the synthesis mode selection switch 25 is sent to the active noise suppression device 17. The voice output mode includes a synthesized voice output mode and a muting sound output mode. This will be described in detail later.

[Internal Configuration of Active Noise Suppression Device 17-1 According to First Embodiment]
Next, the internal configuration of the active noise suppression device 17-1 according to the first embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing an outline of the vehicle active noise suppression system 11-1 according to the first embodiment including the active noise suppression device 17-1 according to the first embodiment.
As shown in FIG. 2, the active noise suppression device 17-1 according to the first embodiment includes an ANC (Active Noise Control) control unit 31, a transfer function acquisition unit 32, an ACP (Active Communication Prompt) control unit 33-1, A first speech synthesizer 35, a second speech synthesizer 37, a first D / A converter DA1, a second D / A converter DA2, a first low-pass filter LPF1, a second low-pass filter LPF2, a third low-pass filter LPF3, A fourth low-pass filter LPF4, a first high-pass filter HPF1, a second high-pass filter HPF2, a first A / D converter AD1, a second A / D converter AD2, a third A / D converter AD3, a fourth A / D converter AD4, And a switching unit 39.

  Specifically, the active noise suppression device 17-1 according to the first embodiment is configured by a microcomputer including, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. Is done.

  The ANC control unit 31 is configured as a functional unit of the microcomputer. This microcomputer reads and executes a program stored in the ROM, and performs execution control such as a noise suppression function of the ANC control unit 31.

  The transfer function acquisition unit 32 is configured as a functional unit of the microcomputer. This microcomputer reads out and executes a program stored in the ROM, and performs execution control such as an open loop transfer function acquisition function described later of the transfer function acquisition unit 32.

  The ACP control unit 33-1 is configured as a functional unit of the microcomputer. This microcomputer reads out and executes a program stored in the ROM, and performs execution control such as a conversation assist function of the ACP control unit 33-1.

  As shown in FIG. 2, the active noise suppression device 17 generates, for example, a first canceling sound by referring to an engine sound (engine rotational speed information) and an error signal e1 related to a sound collected by the first microphone 13A. It has the function to do. This function is realized by the ANC control unit 31. Further, as shown in FIG. 2, the active noise suppression device 17 refers to the engine sound (engine rotational speed information) and the error signal e2 related to the sound collected by the second microphone 15A, and performs the second canceling sound. It has a function to generate. This function is also realized by the ANC control unit 31.

  In short, the ANC control unit 31 performs the first or second canceling sound for suppressing noise in the vehicle interior (including noise generated in the vehicle interior and noise such as engine noise transmitted from outside the vehicle interior). By performing control to output from the corresponding first speaker 13B or second speaker 15B, it plays a role of suppressing noise in the passenger compartment. Further, the ANC control unit 31 adjusts the operational stability of the adaptive filter (see the first adaptive filter 47A and the second adaptive filter 47B in FIG. 3) based on the synthesis mode selection information related to the synthesis mode selection switch 25. It plays the role of setting the value of the step size parameter set to. The detailed configuration of the ANC control unit 31 will be described later in detail.

  In addition, as shown in FIG. 2, the active noise suppression device 17 uses the second microphone 15A to collect the first canceling sound for canceling the noise generated in the front seat space 13 generated by the ANC control unit 31. It has a function of generating a first synthesized voice obtained by synthesizing the error signal e2 related to the spoken voice of the rear seat passenger. This function is realized by the first speech synthesizer 35.

  In addition, as shown in FIG. 2, the active noise suppression device 17 uses the first microphone 13A to absorb the second canceling sound for canceling the noise generated in the rear seat space 15 generated by the ANC control unit 31. It has a function of generating a second synthesized voice by synthesizing the error signal e1 related to the spoken voice of the front seat occupant. This function is realized by the second speech synthesizer 37.

  Further, as shown in FIG. 2, the active noise suppression device 17 generates the first and second synthesized voices, the error signal e1 related to the voice collected by the first microphone 13A, and the second microphone. The error signal e2 related to the sound collected at 15A has a function of removing sound components belonging to the frequency band related to the noise to be suppressed in the passenger compartment. These functions are realized by the first high-pass filter HPF1 and the second high-pass filter HPF2, respectively.

  Further, as shown in FIG. 2, the active noise suppression device 17-1 according to the first embodiment includes the first transfer function C1 and the second speaker related to the path from the first speaker 13B to the second microphone 15A. It has a function of acquiring the second transfer function C2 related to the path from 15B to the first microphone 13A. The function of acquiring the first and second transfer functions C1 and C2 is realized by, for example, measuring the first and second transfer functions C1 and C2 in advance.

The active noise suppression device 17-1 according to the first embodiment includes an active noise suppression device 17-1, a first speaker 13B and a second speaker 15B, a first microphone 13A and a second microphone 15A, and an audio amplifier 19. (However, the audio amplifier 19 may be omitted.) It has a function of acquiring an open-loop transfer function as an entire acoustic system (acoustic signal feedback loop) including the audio system. For example, as shown in FIG. 2, the open loop transfer function acquisition function outputs a measurement signal and uses a transfer function acquisition unit 32 that actually measures the open loop transfer function of the entire acoustic system with respect to the measurement signal. Realized. The transfer function acquisition unit 32 corresponds to the “transfer function acquisition unit” of the present invention.
Thus, an audio amplifier 19 that drives the first speaker 13B and the second speaker 15B, and an acoustic system including an acoustic space from the first speaker 13B or the second speaker 15B to the first microphone 13A or the second microphone 15A are configured. And by acquiring the open-loop transfer function as the whole acoustic system, the accuracy of the open-loop transfer function can be improved.

  In addition, the ACP control unit 33-1 of the active noise suppression device 17-1 according to the first embodiment has a gain coefficient G1, such that the open-loop transfer function is 0 dB (1 time) or less in all frequency bands. Set G2. The ACP control unit 33-1 corresponds to the “setting unit” of the present invention.

Further, as shown in FIG. 2, the active noise suppression device 17-1 according to the first embodiment responds to the error signal e1 related to the conversational voice of the front seat occupant collected by the first microphone 13A as described above. And the gain coefficient G1 set as described above with respect to the error signal e2 related to the conversational voice of the rear-seat occupant collected by the second microphone 15A Has a function of performing a correction for multiplying. These functions are realized by the ACP control unit 33-1. The ACP control unit 33-1 corresponds to the “correction unit” of the present invention.
The ACP control unit 33-1 configured as described above plays a role of smoothly transmitting the voice related to the conversation in the passenger compartment from one to the other.

  The first D / A converter DA1 converts the first synthesized speech in the digital signal form generated by the first speech synthesizer 35 into an analog signal form, and outputs it to the first low-pass filter LPF1. The second D / A converter DA2 converts the second synthesized speech in the digital signal form generated by the second speech synthesizer 37 into an analog signal form and outputs it to the second low-pass filter LPF2.

  The first low-pass filter LPF1 passes an audio signal in a frequency band lower than a cut-off frequency appropriately set to, for example, 200 Hz, among the frequency bands related to the first synthesized voice in the analog signal mode, and an audio amplifier 19 output. The second low-pass filter LPF 2 passes an audio signal in a frequency band lower than the cut-off frequency in the frequency band related to the second synthesized voice of the analog signal, and outputs it to the audio amplifier 19.

  Here, the first low-pass filter LPF1 and the second low-pass filter LPF2 serve as reconstruction filters for reconstructing the first and second synthesized speech in the analog signal mode. As a result, the analog signal waveforms presented by the first and second synthesized speech can be smoothly shaped.

  The third low-pass filter LPF3 outputs an audio signal in a frequency band lower than a cutoff frequency appropriately set to, for example, 200 Hz, among the frequency bands of the analog error signal e1 related to the sound collected by the first microphone 13A. Pass the signal and output it to the first A / D converter AD1 and the first high-pass filter HPF1. The fourth low-pass filter LPF4 passes an audio signal in a frequency band lower than the cut-off frequency in the frequency band of the analog error signal e2 related to the sound collected by the second microphone 15A, The data is output to the D converter AD2 and the second high pass filter HPF2.

Here, the third low-pass filter LPF3 and the fourth low-pass filter LPF4 serve as anti-aliasing filters based on the sampling theorem. Therefore, the cut-off frequencies of the third low-pass filter LPF3 and the fourth low-pass filter LPF4 are set to ½ or less of the sampling frequency exhibited by the microcomputer constituting the ANC control unit 31 and the ACP control unit 33-1.
In this way, if the third low-pass filter LPF3 and the fourth low-pass filter LPF4 are configured by analog filter circuits, it is possible to suppress the load related to the arithmetic processing of the active noise suppression device 17.

  The first A / D conversion unit AD1 converts the analog error signal e1 after the low-pass filter processing by the third low-pass filter LPF3 into a digital error signal e1, and outputs the digital error signal e1 to the ANC control unit 31. The second A / D conversion unit AD2 converts the analog error signal e2 after the low-pass filter processing by the fourth low-pass filter LPF4 into a digital error signal e2, and outputs the digital error signal e2 to the ANC control unit 31.

The first high-pass filter HPF1 passes an audio signal in a high frequency band with respect to the cutoff frequency appropriately set to about 200 to 300 Hz, for example, with respect to the analog error signal e1 after the low-pass filter processing by the third low-pass filter LPF3. Output to the third A / D converter AD3. The second high-pass filter HPF2 passes an audio signal in a frequency band higher than the cut-off frequency with respect to the analog error signal e1 subjected to the low-pass filter processing by the fourth low-pass filter LPF4, so that the fourth A / D converter AD4 Output to.
In this way, if the first high-pass filter HPF1 and the second high-pass filter HPF2 are configured by analog filter circuits, it is possible to suppress the load related to the arithmetic processing of the active noise suppression device 17.

  The third A / D conversion unit AD3 converts the analog error signal e1 after the high-pass filter processing by the first high-pass filter HPF1 into a digital error signal e1, and outputs the digital error signal e1 to the ACP control unit 33-1 through the transfer function acquisition unit 32. . The fourth A / D conversion unit AD4 converts the analog error signal e2 after the high-pass filter processing by the second high-pass filter HPF2 into a digital error signal e2, and outputs the digital error signal e2 to the ACP control unit 33-1 through the transfer function acquisition unit 32. .

  Based on the synthesis mode selection information related to the synthesis mode selection switch 25, the switching unit 39 selects a voice output mode to be used when outputting voice from at least one of the first speaker 13B and the second speaker 15B. It has a function of switching to one of a mode and a muting sound output mode. In the synthesized speech output mode, the active noise suppression device 17 causes the first synthesized speech to be output to the first speaker 13B, while causing the second synthesized speech to be output to the second speaker 15B. In the cancellation sound output mode, the active noise suppression device 17 outputs the first cancellation sound from the first speaker 13B and the second cancellation sound from the second speaker 15B.

[Internal configuration of ANC control unit 31]
Next, the internal configuration of the ANC control unit 31 will be described with reference to FIG. FIG. 3 is a block diagram schematically showing the internal configuration of the ANC control unit 31.
As shown in FIG. 3, the ANC control unit 31 includes a reference signal generation unit 41, a first reference signal generation unit 43A, a second reference signal generation unit 43B, a first filter coefficient update unit 45A, and a second filter coefficient update unit 45B. The first adaptive filter 47A and the second adaptive filter 47B are configured.

  The reference signal generation unit 41 calculates a vibration frequency based on the engine rotation speed information, and generates a reference signal correlated with the calculated vibration frequency. The reference signal generated by the reference signal generation unit 41 is actually generated as a cosine wave signal and a sine wave signal.

  The first reference signal generation unit 43A generates a first reference signal R1 obtained by correcting the reference signal based on the reference signal generated by the reference signal generation unit 41 and the first transfer function C1 obtained by measurement in advance. Generate. Further, the second reference signal generation unit 43B corrects the reference signal based on the reference signal generated by the reference signal generation unit 41 and the second transfer function C2 obtained by measurement in advance. R2 is generated.

The first filter coefficient updating unit 45A includes the first reference signal R1 generated by the first reference signal generation unit 43A, the error signal e1 related to the sound collected by the first microphone 13A, the first transfer function C1, and the first 1. Perform calculation by substituting the step size parameter M1 set when adjusting the operational stability of the adaptive filter 47A into the LMS (Least Mean Square) adaptive algorithm equation (see Equation 1). Thus, the filter coefficient W1 of the first adaptive filter 47A is updated.
W1 _{n + 1} = W1 _n −R1 × e1 × C1 × M1 (Formula 1)

Similarly to the above, the second filter coefficient updating unit 45B includes the second reference signal R2 generated by the second reference signal generation unit 43B, the error signal e2 related to the sound collected by the second microphone 15A, and the second transmission. By substituting the function C2 and the step size parameter M2 set when adjusting the operational stability of the second adaptive filter 47B into the arithmetic expression of the LMS adaptive algorithm (see Expression 2), The filter coefficient W2 of the adaptive filter 47B is updated.
_{W2 n + 1 = W2 n -R2} × e2 × C2 × M2 ( Equation 2)

  Here, the first filter coefficient updating unit 45A sets a smaller value as the step size parameter M1 when the synthesized speech output mode is selected than when the cancellation sound output mode is selected. Similarly, the second filter coefficient updating unit 45B sets a smaller value as the step size parameter M2 when the synthesized speech output mode is selected compared to when the cancellation sound output mode is selected. This is because the filter coefficients W1 and W2 of the first and second adaptive filters 47A and 47B are updated in accordance with the sound collection results relating to the first and second synthesized voices (error signals) in the synthesized voice output mode. Accordingly, it is intended to avoid a situation where the control operation related to active noise suppression becomes unstable.

  The first adaptive filter 47A multiplies the reference signal by a filter coefficient W1 to generate a control signal related to the first canceling sound. Similarly, the second adaptive filter 47B generates a control signal related to the second canceling sound by multiplying the reference signal by the filter coefficient W2. As the first adaptive filter 47A and the second adaptive filter 47B, for example, an adaptive notch filter or an FIR filter can be used as appropriate. The first adaptive filter 47A and the second adaptive filter 47B correspond to the “control signal generator” of the present invention.

  In addition, about the internal structure of the ANC control part 31, it is common between the active noise suppression apparatuses 17-1 and 17-2 which concern on 1st and 2nd embodiment.

[Operation of Active Noise Suppression System 11-1 for Vehicle According to First Embodiment]
Next, with regard to the operation of the vehicle active noise suppression system 11-1 according to the first embodiment, a case where a front seat occupant in the front seat space 13 talks to a rear seat occupant in the rear seat space 15, and the rear seat space 15. A case will be described in which the rear seat occupant in the middle of talking talks to the front seat occupant in the front seat space 13. However, it is assumed that the synthesis mode selection switch 25 is operated to select the synthesis voice output mode.

  In the case where the front seat occupant speaks to the rear seat occupant, the conversation voice of the front seat occupant is first picked up by the first microphone 13A. The analog error signal e1 related to the conversational voice of the front seat occupant collected by the first microphone 13A is input to the third low-pass filter LPF3.

  The third low-pass filter LPF3 is an audio signal having a frequency band lower than the cut-off frequency (for example, 200 Hz) in the frequency band of the analog error signal e1 related to the conversational voice of the front seat occupant collected by the first microphone 13A. Pass through. The analog error signal e1 after the low-pass filter processing by the third low-pass filter LPF3 is input to the first A / D converter AD1 (which will be described later) and the first high-pass filter HPF1.

  The first high-pass filter HPF1 passes an audio signal in a frequency band higher than the cutoff frequency (for example, 200 Hz) with respect to the analog error signal e1 after the low-pass filter processing by the third low-pass filter LPF3. As a result, the audio component belonging to the frequency band lower than the cutoff frequency is removed (the gain of the audio component is attenuated). The frequency band of the voice component thus removed is common to the frequency band of noise (including engine noise) that is controlled by the ANC control unit 31. As a result, it is possible to avoid the situation where the gain of the frequency band related to noise diverges, and to stabilize the control operation related to active noise suppression.

  The analog error signal e1 after the high-pass filter processing by the first high-pass filter HPF1 is input to the third A / D converter AD3. The third A / D converter AD3 converts the analog error signal e1 after the high-pass filter processing by the first high-pass filter HPF1 into a digital error signal e1. The converted digital error signal e1 is input to the ACP control unit 33-1 via the transfer function acquisition unit 32.

  The ACP control unit 33-1 corrects the converted digital error signal e1 by a gain coefficient G2 set so that the open-loop transfer function is 0 dB (1 times) or less in all frequency bands. Do. Thereby, the situation where a howling phenomenon occurs can be avoided beforehand by stabilizing the control operation related to active noise suppression. The digital error signal e <b> 1 related to the conversational voice of the front seat occupant corrected by the ACP control unit 33-1 is input to the second speech synthesis unit 37.

  On the other hand, in order to realize active noise suppression in the rear seat space 15, the analog error signal e2 relating to the noise generated in the rear seat space 15 collected by the second microphone 15A is input to the fourth low-pass filter LPF4. .

  The fourth low-pass filter LPF4 is lower than the cut-off frequency (for example, about 200 to 500 Hz) in the frequency band of the analog error signal e2 related to the noise generated in the rear seat space 15 collected by the second microphone 15A. Pass audio signals in the frequency band. The analog error signal e2 subjected to the low-pass filter processing by the fourth low-pass filter LPF4 is input to the second A / D conversion unit AD2 and the second high-pass filter HPF2 (which will be described later).

  The second A / D converter AD2 converts the analog error signal e2 after the low-pass filter processing by the fourth low-pass filter LPF4 into a digital error signal e2. The converted digital error signal e2 is input to the second filter coefficient updating unit 45B of the ANC control unit 31.

  The reference signal generation unit 41 of the ANC control unit 31 generates a reference signal that correlates with the vibration frequency calculated based on the engine rotation speed information. The second reference signal generation unit 43B corrects the reference signal based on the reference signal generated by the reference signal generation unit 41 and the second transfer function C2 obtained by measurement in advance. Is generated.

  The second filter coefficient updating unit 45B includes a second reference signal R2 generated by the second reference signal generation unit 43B, an error signal e2 related to noise generated in the rear seat space 15 collected by the second microphone 15A, 2 By substituting the transfer function C2 and the step size parameter M2 set when adjusting the operational stability of the second adaptive filter 47B into the above equation 2, and performing the calculation, the filter coefficient of the second adaptive filter 47B Update W2.

  In updating the filter coefficient W2, the second filter coefficient updating unit 45B sets a smaller value as the step size parameter M2 when the synthesized speech output mode is selected than when the cancellation sound output mode is selected. Set. Thereby, the situation where the control action concerning active noise suppression becomes unstable can be avoided beforehand.

  Next, the second adaptive filter 47B generates a control signal related to the second canceling sound by multiplying the reference signal by the filter coefficient W2. The control signal related to the second canceling sound generated to cancel the noise generated in the rear seat space 15 is input to the second speech synthesizer 37.

  The second speech synthesizer 37 corrects the conversational voice of the front seat occupant corrected by the ACP control unit 33-1 with respect to the control signal related to the second canceling sound for canceling the noise generated in the rear seat space 15. A second synthesized speech is generated by synthesizing the digital error signal e1 according to the above. The second synthesized speech generated in this way is input to the second D / A converter DA2.

  The second D / A converter DA2 converts the second synthesized speech in the digital signal form generated by the second speech synthesizer 37 into an analog signal form. The second synthesized speech in the analog signal mode after conversion is input to the second low-pass filter LPF2.

The second low-pass filter LPF2 passes an audio signal in a frequency band lower than the cut-off frequency (for example, about 200 to 500 Hz) in the frequency band related to the second synthesized voice in the analog signal mode. Second synthesized speech in an analog signal form after low-pass filter processing by the second low-pass filter LPF2 (error signal e1 related to the conversational voice of the front-seat occupant + second canceling sound for canceling noise generated in the rear seat space 15 ) Is output through the second speaker 15B after predetermined amplification by the audio amplifier 19.
The second synthesized voice in the analog signal mode output via the second speaker 15B includes the conversation voice of the front seat occupant and the second canceling sound for canceling the noise generated in the rear seat space 15. For this reason, conversation assistance in the closed space from the front seat occupant to the rear seat occupant and the active noise suppression in the rear seat space 15 can be achieved at the same time.

  Next, in the case where the rear seat occupant speaks to the front seat occupant, the conversation voice of the rear seat occupant is first picked up by the second microphone 15A. The analog error signal e2 related to the conversational voice of the rear seat occupant picked up by the second microphone 15A is transmitted through the fourth low-pass filter LPF4 to the second A / D conversion unit AD2 (described later) and the second It is input to the high pass filter HPF2.

  The second high-pass filter HPF2 passes an audio signal in a frequency band higher than the cutoff frequency (for example, about 200 to 300 Hz) with respect to the analog error signal e2 subjected to the low-pass filter processing by the fourth low-pass filter LPF4. As a result, the audio component belonging to the frequency band lower than the cutoff frequency is removed (the gain of the audio component is attenuated). The frequency band of the voice component thus removed is common to the frequency band of noise (including engine noise) that is controlled by the ANC control unit 31. As a result, it is possible to avoid the situation where the gain of the frequency band related to noise diverges, and to stabilize the control operation related to active noise suppression.

  The analog error signal e2 after the high-pass filter processing by the second high-pass filter HPF2 is input to the fourth A / D conversion unit AD4. The fourth A / D converter AD4 converts the analog error signal e2 after the high-pass filter processing by the second high-pass filter HPF2 into a digital error signal e2. The converted digital error signal e2 is input to the ACP control unit 33-1 via the transfer function acquisition unit 32.

  The ACP control unit 33-1 performs correction for multiplying the converted digital error signal e2 by a gain coefficient G1 set so that the open-loop transfer function is 0 dB (1 times) or less in all frequency bands. Do. Thereby, the situation where a howling phenomenon occurs can be avoided beforehand by stabilizing the control operation related to active noise suppression. The digital error signal e <b> 2 related to the conversational voice of the rear seat occupant corrected by the ACP control unit 33-1 is input to the first speech synthesis unit 35.

  On the other hand, in order to realize active noise suppression in the front seat space 13, the analog error signal e1 related to the noise generated in the front seat space 13 collected by the first microphone 13A is passed through the third low pass filter LPF3. The signals are input to the first A / D converter AD1 and the first high-pass filter HPF1 (which will be described later).

  The first A / D converter AD1 converts the analog error signal e1 after the low-pass filter processing by the third low-pass filter LPF3 into a digital error signal e1. The converted digital error signal e1 is input to the first filter coefficient updating unit 45A of the ANC control unit 31.

  The reference signal generation unit 41 of the ANC control unit 31 generates a reference signal that correlates with the vibration frequency calculated based on the engine rotation speed information. The first reference signal generation unit 43A corrects the reference signal based on the reference signal generated by the reference signal generation unit 41 and the first transfer function C1 obtained by measurement in advance. Is generated.

  The first filter coefficient updating unit 45A includes a first reference signal R1 generated by the first reference signal generation unit 43A, an error signal e1 related to noise generated in the front seat space 13 collected by the first microphone 13A, and a first The filter coefficient of the first adaptive filter 47A is calculated by substituting the transfer function C1 and the step size parameter M1 that is set when adjusting the operational stability of the first adaptive filter 47A into the equation 1 above. Update W1.

  In updating the filter coefficient W1, the first filter coefficient updating unit 45A sets a smaller value as the step size parameter M1 when the synthesized speech output mode is selected compared to when the cancellation sound output mode is selected. Set. Thereby, the situation where the control action concerning active noise suppression becomes unstable can be avoided beforehand.

  Next, the first adaptive filter 47A multiplies the reference signal by the filter coefficient W1 to generate a control signal related to the first canceling sound. The control signal related to the first canceling sound for canceling the noise generated in the front seat space 13 is input to the first speech synthesizer 35.

  The first voice synthesizer 35 corrects the conversational voice of the rear seat occupant after the ACP control unit 33-1 corrects the control signal related to the first canceling sound to cancel the noise generated in the front seat space 13. A first synthesized speech is generated by synthesizing the digital error signal e2 according to the above. The first synthesized speech generated in this way is input to the first D / A converter DA1.

  The first D / A converter DA1 converts the first synthesized speech in the digital signal form generated by the first speech synthesizer 35 into an analog signal form. The first synthesized speech in the analog signal mode after conversion is input to the first low-pass filter LPF1.

The first low-pass filter LPF1 passes an audio signal having a frequency band lower than a cut-off frequency (for example, about 200 to 300 Hz) in the frequency band related to the first synthesized voice in the analog signal mode. The first synthesized speech in the form of an analog signal after the low-pass filter processing by the first low-pass filter LPF1 (the error signal e2 + related to the conversational voice of the rear-seat occupant + the first canceling sound for canceling the noise generated in the front seat space 13 ) Is output through the first speaker 13B after predetermined amplification by the audio amplifier 19.
The first synthesized voice of the analog signal mode output via the first speaker 13B includes the conversation voice of the rear seat occupant and the first canceling sound for canceling the noise generated in the front seat space 13. For this reason, conversation assistance in the closed space from the rear seat occupant to the front seat occupant and active noise suppression in the front seat space 13 can both be achieved accurately.

[Internal Configuration of Active Noise Suppression Device 17-2 According to Second Embodiment]
Next, the internal configuration of the active noise suppression device 17-2 according to the second embodiment will be described with reference to FIG. FIG. 4: is a block diagram showing the outline | summary of the active noise suppression system 11-2 for vehicles which concerns on 2nd Embodiment provided with the active noise suppression apparatus 17-2 which concerns on 2nd Embodiment.
The active noise suppression device 17-1 according to the first embodiment and the active noise suppression device 17-2 according to the second embodiment have components having common basic functions. Therefore, by focusing attention on the differences between the first and second embodiments and explaining the differences, the configuration description of the active noise suppression device 17-2 according to the second embodiment will be substituted.

  In the active noise suppression device 17-2 according to the second embodiment, the first operational amplifier OP1 is used to amplify the analog error signal e1 to an appropriate gain, while the second operational amplifier OP2 is used to perform analog processing. A configuration is employed in which processing for amplifying the error signal e2 to an appropriate gain is performed. Note that amplification processing using the first operational amplifier OP1 or the second operational amplifier OP2 is performed by analog signal processing.

In the active noise suppression device 17-2 according to the second embodiment, the ACP control unit 33-2 sets the gain coefficients G <b> 3 and G <b> 4 based on the synthesis mode selection information related to the synthesis mode selection switch 25. The gain of the first operational amplifier OP1 is set based on the gain coefficient G3, while the gain of the second operational amplifier OP2 is set based on the gain coefficient G4.
Specifically, when the synthesis mode selection information is on (the voice output mode is the synthesized voice output mode), the gains of the first and second opamps OP1 and OP2 are relatively high values (for example, 0.7 to 1). Degree). On the other hand, when the synthesis mode selection information is off (the audio output mode is the muting output mode), the gains of the first and second opamps OP1 and OP2 are relatively low values (for example, about 0 to 0.3). Is set.

  In the active noise suppression device 17-1 according to the first embodiment, the noise (targeted by the ANC control unit 31 to be suppressed) from the error signal e <b> 1 related to the conversation voice in the front seat space 13 collected by the first microphone 13 </ b> A. In order to remove a sound component in a frequency band related to engine noise (attenuating the gain of the sound component), a cut-off frequency (for example, about 200 to 300 Hz) is used for the error signal e1 using the first high-pass filter HPF1. ) Is applied to a process of passing an audio signal in a high frequency band. On the other hand, from the error signal e2 related to the conversation voice in the rear seat space 15 picked up by the second microphone 15A, the voice component of the frequency band related to the noise (including engine noise) targeted for suppression by the ANC control unit 31 is obtained. In order to remove (attenuate the gain of the same audio component), an audio signal in a frequency band higher than the cutoff frequency (for example, about 200 to 300 Hz) is passed to the error signal e2 using the second high-pass filter HPF2. The structure which performs processing is adopted.

On the other hand, in the active noise suppression device 17-2 according to the second embodiment, the ANC control unit 31 is subject to suppression from the error signal e1 related to the conversation voice in the front seat space 13 collected by the first microphone 13A. In order to remove the sound component of the frequency band related to the noise (including engine noise) (the gain of the sound component is attenuated), the first operational amplifier OP1 performs the second operation on the analog error signal e1 after amplification processing. A configuration is adopted in which processing for passing an audio signal belonging to a required frequency bandwidth is performed using a one-band pass filter BPF1. On the other hand, from the error signal e2 related to the conversation voice in the rear seat space 15 picked up by the second microphone 15A, the voice component of the frequency band related to the noise (including engine noise) targeted for suppression by the ANC control unit 31 is obtained. In order to remove (attenuate the gain of the same audio component), the audio signal belonging to the required frequency bandwidth using the second bandpass filter BPF2 with respect to the analog error signal e2 amplified by the second operational amplifier OP2 The structure which performs the process which passes is adopted.
Note that the bandpass filter processing using the first bandpass filter BPF1 and the second bandpass filter BPF2 is performed by analog signal processing.
The analog error signal e1 amplified by the first bandpass filter BPF1 is input to the second speech synthesizer 37. On the other hand, the analog error signal e2 amplified by the second bandpass filter BPF2 is input to the first speech synthesizer 35.

[Operation of Active Noise Suppression System 11-2 for Vehicle According to Second Embodiment]
Next, regarding the operation of the vehicle active noise suppression system 11-2 according to the second embodiment, a case where a front seat occupant in the front seat space 13 talks to a rear seat occupant in the rear seat space 15, and the rear seat space 15. A case will be described in which the rear seat occupant in the middle of talking talks to the front seat occupant in the front seat space 13. However, it is assumed that the synthesis mode selection switch 25 has been operated to select the synthesis voice output mode (synthesis mode selection information is turned on).

  In the case where the front seat occupant speaks to the rear seat occupant, the conversation voice of the front seat occupant is first picked up by the first microphone 13A. The analog error signal e1 related to the conversation voice of the front seat occupant picked up by the first microphone 13A is input to the first operational amplifier OP1 and the third low-pass filter LPF3, respectively.

  The first operational amplifier OP1 uses the gain based on the gain coefficient G3 set by the ACP control unit 33-2 on the analog error signal e1 related to the conversational voice of the front seat occupant collected by the first microphone 13A. Amplify. The analog error signal e1 amplified by the first operational amplifier OP1 is input to the first band pass filter BPF1.

  The first band pass filter BPF1 passes an audio signal belonging to a required frequency bandwidth with respect to the analog error signal e1 amplified by the first operational amplifier OP1. As a result, the audio component in the frequency band related to the noise (including engine noise) targeted by the ANC control unit 31 is removed (gain of the audio component is attenuated). The analog error signal e1 related to the conversational voice of the front seat occupant after the bandpass filter processing by the first bandpass filter BPF1 is input to the second speech synthesizer 37.

  On the other hand, in order to realize active noise suppression in the rear seat space 15, the analog error signal e2 relating to the noise generated in the rear seat space 15 collected by the second microphone 15A is input to the fourth low-pass filter LPF4. .

  The fourth low-pass filter LPF4 is lower than the cut-off frequency (for example, about 200 to 500 Hz) in the frequency band of the analog error signal e2 related to the noise generated in the rear seat space 15 collected by the second microphone 15A. Pass audio signals in the frequency band. The analog error signal e2 after the low-pass filter processing by the fourth low-pass filter LPF4 is input to the second A / D converter AD2.

  The second A / D converter AD2 converts the analog error signal e2 after the low-pass filter processing by the fourth low-pass filter LPF4 into a digital error signal e2. The converted digital error signal e2 is input to the ANC control unit 31.

  The ANC control unit 31 uses the reference signal correlated with the vibration frequency calculated based on the engine rotation speed information, the digital error signal e2, and the like to generate the second canceling sound for canceling the noise in the rear seat space 15. Such a control signal is generated. The control signal related to the second canceling sound generated in this way is input to the second D / A converter DA2.

  The second D / A converter DA2 converts the second cancellation sound in the digital signal mode into an analog signal mode. The second canceling sound in the analog signal mode after conversion is input to the second low-pass filter LPF2.

  The second low-pass filter LPF2 passes an audio signal having a frequency band lower than the cut-off frequency (for example, about 200 to 500 Hz) in the frequency band related to the second canceling sound in the analog signal mode. A control signal related to the second canceling sound for canceling the noise generated in the rear seat space 15 after the low-pass filter processing by the second low-pass filter LPF 2 is input to the second speech synthesizer 37.

The second speech synthesizer 37 converts the analog signal generated by the ANC control unit 31 into a second canceling sound (output of the second low-pass filter LPF2) for canceling the noise generated in the rear seat space 15. On the other hand, a second synthesized voice is generated by synthesizing the analog error signal e1 (the output of the first bandpass filter BPF1) related to the conversational voice of the front seat occupant. The second synthesized speech generated in this way (the error signal e1 related to the conversational speech of the front seat occupant + the second canceling sound for canceling the noise generated in the rear seat space 15) is amplified by the audio amplifier 19 with a predetermined amplification. Then, it is output via the second speaker 15B.
The second synthesized voice in the analog signal mode output via the second speaker 15B includes the conversation voice of the front seat occupant and the second canceling sound for canceling the noise generated in the rear seat space 15. For this reason, conversation assistance in the closed space from the front seat occupant to the rear seat occupant and the active noise suppression in the rear seat space 15 can be achieved at the same time.

  Next, in the case where the rear seat occupant speaks to the front seat occupant, the conversation voice of the rear seat occupant is first picked up by the second microphone 15A. The analog error signal e2 related to the conversational voice of the rear seat occupant picked up by the second microphone 15A is input to the second operational amplifier OP2 and the fourth low-pass filter LPF4, respectively.

  The second operational amplifier OP2 uses the gain based on the gain coefficient G4 set by the ACP control unit 33-2 for the analog error signal e2 related to the conversational voice of the rear seat occupant collected by the second microphone 15A. Amplify. The analog error signal e2 amplified by the second operational amplifier OP2 is input to the second bandpass filter BPF2.

  The second band pass filter BPF2 passes an audio signal belonging to a required frequency bandwidth with respect to the analog error signal e2 amplified by the second operational amplifier OP2. As a result, the audio component in the frequency band related to the noise (including engine noise) targeted by the ANC control unit 31 is removed (gain of the audio component is attenuated). The analog error signal e2 related to the conversational voice of the rear passenger after bandpass filter processing by the second bandpass filter BPF2 is input to the first speech synthesizer 35.

  On the other hand, in order to realize active noise suppression in the front seat space 13, the analog error signal e1 related to the noise generated in the front seat space 13 collected by the first microphone 13A is input to the third low-pass filter LPF3. .

  The third low-pass filter LPF3 is lower than the cut-off frequency (for example, about 200 to 500 Hz) in the frequency band of the analog error signal e1 related to the noise generated in the front seat space 13 collected by the first microphone 13A. Pass audio signals in the frequency band. The analog error signal e1 after the low-pass filter processing by the third low-pass filter LPF3 is input to the first A / D converter AD1.

  The first A / D converter AD1 converts the analog error signal e1 after the low-pass filter processing by the third low-pass filter LPF3 into a digital error signal e1. The converted digital error signal e1 is input to the ANC control unit 31.

  The ANC control unit 31 performs first cancellation for canceling noise generated in the front seat space 13 based on a reference signal correlated with the vibration frequency calculated based on the engine rotation speed information, the digital error signal e1, and the like. A control signal related to sound is generated. The control signal related to the first canceling sound generated in this way is input to the first D / A converter DA1.

  The first D / A converter DA1 converts the first cancellation sound in the digital signal mode into an analog signal mode. The first cancellation sound in the analog signal mode after conversion is input to the first low-pass filter LPF1.

  The first low-pass filter LPF1 passes an audio signal in a frequency band lower than the cutoff frequency (for example, about 200 to 500 Hz) in the frequency band related to the first canceling sound in the analog signal mode. The first cancellation sound in the analog signal mode for canceling the noise generated in the front seat space 13 after the low-pass filter processing by the first low-pass filter LPF 1 is input to the first speech synthesizer 35.

The first speech synthesizer 35 uses the analog signal generated by the ANC control unit 31 as the first canceling sound (output of the first low-pass filter LPF1) for canceling the noise generated in the front seat space 13. On the other hand, the first synthesized voice is generated by synthesizing the analog error signal e2 (output of the second bandpass filter BPF2) related to the conversational voice of the rear seat passenger. The first synthesized speech generated in this way is output through the first speaker 13B after being amplified by the audio amplifier 19 in a predetermined manner.
The first synthesized voice of the analog signal mode output via the first speaker 13B includes the conversation voice of the rear seat occupant and the first canceling sound for canceling the noise generated in the front seat space 13. For this reason, conversation assistance in the closed space from the rear seat occupant to the front seat occupant and active noise suppression in the front seat space 13 can both be achieved accurately.

[Operational effects of the active noise suppression system 11 for vehicles]
Next, the effect of the vehicle active noise suppression system 11 will be described.

  In the vehicle active noise suppression system 11 according to the embodiment of the present invention, the active noise suppression device 17 refers to the noise and the sound (error signal e1) collected by the first microphone (first sound collection unit) 13A. The first synthesized sound is generated by synthesizing the sound (error signal e2) collected by the second microphone (second sound collection unit) 15A with the first canceling sound generated in this manner. The first microphone (first sound collection) is generated with respect to the second canceling sound generated with reference to the voice synthesis unit 35 and the sound collected by the noise and the second microphone (second sound collection unit) 15A. Part) a second voice synthesizing unit 37 for generating a second synthesized voice obtained by synthesizing the voice collected by 13A. The active noise suppression device 17 outputs the first synthesized voice to the first speaker (first voice output unit) 13B, and outputs the second synthesized voice to the second speaker (second voice output unit) 15B. When the first and second synthesized voices are generated and the voices collected by the first microphone 13A and the voices picked up by the second microphone 15A are generated in the closed space (vehicle interior) A process for removing each of the sound components belonging to the frequency band related to the noise to be suppressed is performed.

According to the active noise suppression system 11 for a vehicle according to the embodiment of the present invention, it is possible to accurately achieve both conversation assistance and active noise suppression in the passenger compartment.
Moreover, according to the vehicle active noise suppression system 11-1 according to the first embodiment, compared to the conventional active noise suppression device that suppresses noise generated in the passenger compartment, the synthesis mode selection switch 25 and the ACP control unit 33-1. , First speech synthesizer 35, second speech synthesizer 37, switching unit 39, first high-pass filter HPF1, second high-pass filter HPF2, third A / D converter AD3, and fourth A / D converter AD4 By adding, a conversation assist function for assisting smooth conversation in the vehicle compartment can be incorporated relatively easily.

  Furthermore, according to the vehicle active noise suppression system 11-2 according to the second embodiment, compared to the conventional active noise suppression device for suppressing noise generated in the vehicle interior, the synthesis mode selection switch 25, the ACP control unit 33-2. A first speech synthesizer 35, a second speech synthesizer 37, a first operational amplifier OP1, a second operational amplifier OP2, a first bandpass filter BPF1, and a second bandpass filter BPF2. Thus, a conversation assist function for assisting smooth conversation in the passenger compartment can be incorporated relatively easily.

  Further, the active noise suppression device 17-1 according to the first embodiment includes an active noise suppression device 17-1, a first speaker 13B (first audio output unit), and a second speaker (second audio output unit) 15B. , A first microphone (first sound collection unit) 13A, a second microphone (second sound collection unit) 15A, and an audio amplifier 19 (however, the audio amplifier 19 may be omitted). The transfer function acquisition unit 32 that acquires the open loop transfer function of the acoustic system and the open loop transfer function acquired by the transfer function acquisition unit 32 (preferably in all frequency bands) is 0 dB (1 time) or less. The ACP control unit (setting unit) 33-1 for setting the gain coefficients G1 and G2 and the error signal e1 relating to the conversational voice of the front seat occupant collected by the first microphone 13A ACP for performing the correction for multiplying the set gain coefficient G2 and for multiplying the error signal e2 related to the conversational voice of the rear-seat occupant collected by the second microphone 15A by the set gain coefficient G1. You may employ | adopt the structure provided with the control part (correction | correction part) 33-1.

  If comprised in this way, the ACP control part 33-1 will carry out the correction | amendment which multiplies the set gain coefficient G2 with respect to the error signal e1 which concerns on the conversational voice of the front seat passenger | crew collected by the 1st microphone 13A. And the correction of multiplying the error signal e2 related to the conversational voice of the rear-seat occupant collected by the second microphone 15A by the set gain coefficient G1 makes it possible to stabilize the control operation related to active noise suppression. As a result, it is possible to accurately achieve both conversation assistance and active noise suppression in a closed space while avoiding the occurrence of a howling phenomenon.

  In addition, the active noise suppression device 17 uses a sound output mode used when outputting sound from at least one of the first speaker (first sound output unit) 13B or the second speaker (second sound output unit) 15B. The first synthesized voice is output to the first speaker 13B while the second synthesized voice is output to the second speaker 15B, and the first or second canceling sound is output to the first speaker 13B. The reference signal generators 43A and 43B that can switch the cancellation sound output mode to be output from at least one of the second speaker 15B and generate a reference signal based on at least a reference signal correlated with noise, and a reference signal The reference signals R1, R2 generated by the generation units 43A, 43B, the voice collected by the first microphone 13A or the second microphone 15 Filter of the adaptive filters 47A and 47B using the error signal (e1 or e2) relating to the sound collected in step S1 and the step size parameters M1 and M2 set when adjusting the coefficient update amounts of the adaptive filters 47A and 47B. Filter coefficient updating units 45A and 45B that update the coefficients W1 and W2, and an adaptation that generates a control signal related to the first or second canceling sound by multiplying the reference signal by the filter coefficients W1 and W2 of the adaptive filters 47A and 47B Filters (control signal generation units) 47A and 47B, and step size parameters M1 and M2 when the synthesized speech output mode is selected are smaller than when the cancellation sound output mode is selected. A configuration in which is set may be adopted.

  If comprised in this way, regardless of which synthetic | combination audio | voice output mode or cancellation sound output mode is selected as audio | voice output mode, the control action which concerns on the active noise suppression accompanying the filter coefficient update of adaptive filter 47A, 47B Stability can be ensured.

  In addition, the ACP control unit 33-1 of the active noise suppression device 17-1 according to the first embodiment sets a value less than 1 exceeding 0 as a gain coefficient when the synthesized speech output mode is selected, When the canceling sound output mode is selected, 0 is set as the gain coefficient, and the switching of the sound output mode from one of the synthesized sound output mode or the canceling sound output mode to the other is performed with a predetermined time constant. A configuration may be adopted.

With this configuration, when the synthesized speech output mode is selected, an error signal (e1 or e2) related to the sound collected by the first microphone 13A or the sound collected by the second microphone 15A. On the other hand, correction for multiplying a gain coefficient by a value less than 1 exceeding 0 is performed. In this case, the influence of the error signal can be suppressed.
On the other hand, when the canceling sound output mode is selected, a gain coefficient is obtained for the error signal (e1 or e2) related to the sound collected by the first microphone 13A or the sound collected by the second microphone 15A. As shown in FIG. In this case, the influence of the error signal can be eliminated.
In addition, since the switching of the voice output mode from one of the synthesized voice output mode or the cancellation sound output mode to the other is performed with a predetermined time constant, for example, when the gain coefficient is switched with the switching of the voice output mode Even so, it is possible to suppress the generation of abnormal noise when the audio output mode is switched instantaneously (without providing a predetermined time constant).
As described above, according to the vehicle active noise suppression system 11 according to the embodiment of the present invention, the vehicle is used in all frequency bands regardless of which one of the synthesized speech output mode and the cancellation sound output mode is selected. The control stability in the active noise suppression system 11 can be ensured.

In the vehicle active noise suppression system 11-2 according to the second embodiment of the present invention, the first synthesized speech is synthesized by synthesizing the analog error signal e2 in the analog signal mode with the first canceling sound. (The second synthesized speech is generated by synthesizing the analog error signal e1 in the analog signal form with respect to the second canceling sound), so that the processing capacity (sampling) of the active noise suppression device 17-2 Regardless of the time), it is possible to expect the effect of clearly transmitting the voice of one of the front and rear seats to the other passenger.
The reason for this is that, in general, when converting an analog audio signal into a digital audio signal, if the control processing capability of a control device such as a microcomputer is low, components necessary for recognizing the passenger's voice as a language are dropped from the output. This is because in the case of the second embodiment, such a problem can be prevented in advance.

  In particular, in the vehicle active noise suppression system 11-2 according to the second embodiment of the present invention, the frequency band related to the noise (including engine noise) targeted by the ANC control unit 31 is cut using a bandpass filter. As a result of the off-processing, the stability of the active noise suppression control is ensured, and at the same time, the voice component in the band outside the frequency band to which the occupant's conversation voice belongs can be appropriately cut off. You can expect an effect to communicate.

[Other Embodiments]
The embodiment described above shows an embodiment of the present invention. Therefore, the technical scope of the present invention should not be limitedly interpreted by these. This is because the present invention can be implemented in various forms without departing from the gist or main features thereof.

  For example, in the description according to the embodiment of the present invention, the engine sound is illustrated as an example of the vehicle interior noise, but the present invention is not limited to this example. In addition to engine noise, for example, in general, noise that includes road noise (sound generated when the tire touches the road surface) and drumming noise (sound generated when the roof panel or floor panel vibrates during driving) Can be applied.

  In the description according to the embodiment of the present invention, the cut-off frequency set for the first low-pass filter LPF1, the second low-pass filter LPF2, the third low-pass filter LPF3, and the fourth low-pass filter LPF4 is, for example, about 200 to 500 Hz. However, the present invention is not limited to this example. The cut-off frequency set for each of the first low-pass filter LPF1, the second low-pass filter LPF2, the third low-pass filter LPF3, and the fourth low-pass filter LPF4 is the vehicle active noise suppression system 11 according to the embodiment of the present invention. In view of exhibiting sufficient performance, an appropriate value may be set.

  Further, in the description according to the embodiment of the present invention, the cut-off frequency set for the first high-pass filter HPF1 and the second high-pass filter HPF2 has been described as an example, for example, about 200 to 300 Hz. It is not limited to. As the cut-off frequency set for each of the first high-pass filter HPF1 and the second high-pass filter HPF2, the vehicle active noise suppression system 11 according to the embodiment of the present invention exhibits sufficient performance as described above. An appropriate value may be set in consideration of the above.

  Moreover, in the description which concerns on embodiment of this invention, although the example which mounted the active noise suppression system which concerns on this invention in the indoor space of the vehicle was given and demonstrated, this invention is not limited to this example. The active noise suppression system according to the present invention may be applied to, for example, an indoor space of an aircraft or an indoor space of a railway vehicle.

Further, in the description according to the embodiment of the present invention, an example in which one speaker (first speaker 13B) is provided in the front seat space 13 in the vehicle interior has been described, but the present invention is not limited to this example. In the vehicle active noise suppression system 11 according to the embodiment of the present invention, for example, a configuration in which speakers are provided on both sides of the driver seat side and the passenger seat side in the front seat space 13 in the vehicle interior may be employed.
It is assumed that a navigation device that guides a route to a destination via an image and sound is mounted on the vehicle V having such a configuration. In this case, the guidance voice by the navigation device is output from the driver's seat side speaker. In addition, the voice output mode of the active noise suppression system to which the driver's seat side speaker belongs is synthesized so that the driver's seat side speaker does not output the voice from the rear seat space 15 while the navigation device is outputting the guidance voice. A configuration in which the sound output mode is switched to the mute output mode may be employed.

  Further, in the description according to the embodiment of the present invention, the voice output mode is set to the synthesized voice output mode or the cancellation sound output mode based on the synthesis mode selection information selected through the operation of the synthesis mode selection switch 25 by the occupant. Although an example of switching to one of them has been described, the present invention is not limited to this example. You may employ | adopt the structure which switches audio | voice output mode according to a vehicle state or a disturbance (noise) state. Specifically, for example, when the control operation related to active noise suppression is unstable (for example, the collected sound from the microphone tends to diverge), the voice output mode from the synthesized voice output mode to the cancellation sound output mode. A configuration for performing switching may be employed.

  Further, in the description according to the embodiment of the present invention, the transfer function acquisition unit 32 that acquires the open loop transfer function as the entire acoustic system is configured as a functional unit (software) included in the active noise suppression device (microcomputer) 17. However, the present invention is not limited to this example. The transfer function acquisition unit 32 may adopt a configuration in which an open loop transfer function is acquired by storing an open loop transfer function of the entire acoustic system that has been measured in advance using a measuring instrument in a design stage. .

  Further, in the description according to the second embodiment of the present invention, the first and second bands are used to remove the audio signal components in the frequency band related to the noise (including engine noise) targeted by the ANC control unit 31. Although an example using the pass filters BPF1 and BPF2 has been described, the present invention is not limited to this example. Instead of the first and second band-pass filters BPF1 and BPF2, a high-pass filter that can remove an audio signal component in a band corresponding to a frequency band related to noise to be suppressed may be employed.

11-1 Active Noise Suppression System for Vehicle according to First Embodiment (Active Noise Suppression System)
11-2 Active Noise Suppression System for Vehicle according to Second Embodiment (Active Noise Suppression System)
13 Front seat space (first space)
13A First microphone (first sound collection unit)
13B 1st speaker (1st audio | voice output part)
15 Rear seat space (second space)
15A Second microphone (second sound collection unit)
15B 2nd speaker (2nd audio | voice output part)
17-1 Active noise suppression device (transfer function acquisition unit) according to the first embodiment
17-2 Active Noise Suppressing Device According to Second Embodiment 25 Synthesis Mode Selection Switch 31 ANC Control Unit 32 Transfer Function Acquisition Unit 33-1 ACP Control Unit (Setting Unit and Correction Unit) according to First Embodiment
33-2 ACP Control Unit According to Second Embodiment 35 First Speech Synthesis Unit 37 Second Speech Synthesis Unit 39 Switching Unit 41 Reference Signal Generation Unit 43A First Reference Signal Generation Unit 43B Second Reference Signal Generation Unit 45A First 1 filter coefficient updating unit 45B second filter coefficient updating unit 47A first adaptive filter 47B second adaptive filter C1 first transfer function C2 second transfer function e1 error signal e2 error signal HPF1 first high pass filter HPF2 second high pass filter M1 Step size parameter M2 Step size parameter W1 Filter coefficient of first adaptive filter 47A W2 Filter coefficient of second adaptive filter 47B

Claims (5)

A first sound collecting unit that is provided in the first space in the closed space and collects the sound generated in the first space;
A second sound collection unit that is provided in a second space apart from the first space in the closed space and collects sound generated in the second space;
A first sound output unit provided in the first space and outputting sound;
A second sound output unit provided in the second space for outputting sound;
An active noise suppression device that performs control to output a canceling sound for suppressing noise in the closed space from at least one of the first audio output unit and the second audio output unit; An active noise suppression system that actively suppresses the noise,
The active noise suppression device is:
The first sound that is generated by referring to the noise and the sound collected by the first sound collection unit is combined with the sound collected by the second sound collection unit. A first speech synthesizer for generating synthesized speech;
Second sound obtained by synthesizing the sound collected by the first sound collection unit with the second canceling sound generated with reference to the noise and the sound collected by the second sound collection unit A second speech synthesizer for generating synthesized speech,
Performing control to output the second synthesized voice to the second voice output unit while outputting the first synthesized voice to the first voice output unit;
When generating the first and second synthesized speech, suppression in the closed space from the sound collected by the first sound collection unit and the sound collected by the second sound collection unit An active noise suppression system that performs a process of removing a voice component belonging to a frequency band related to a target noise. The active noise suppression system according to claim 1,
The active noise suppression device is:
An open loop of an acoustic system including the active noise suppression device, the first sound output unit and the second sound output unit, and the first sound collection unit and the second sound collection unit. A transfer function acquisition unit for acquiring a transfer function;
A setting unit for setting a gain coefficient at which the open-loop transfer function acquired by the transfer function acquisition unit is 0 dB or less;
A correction unit that performs correction by multiplying an error signal related to the sound collected by the first sound collection unit and the second sound collection unit by a gain coefficient set by the setting unit;
An active noise suppression system comprising: The active noise suppression system according to claim 1 or 2,
The active noise suppression device is:
As the audio output mode used when outputting audio from at least one of the first audio output unit and the second audio output unit, the first audio output unit outputs the first synthesized audio. On the other hand, the synthesized speech output mode for outputting the second synthesized speech to the second speech output unit, and the first or second canceling sound as the first speech output unit and the second speech output unit. The cancellation sound output mode to be output from at least one of them can be switched,
The active noise suppression device is:
A reference signal generator for generating a reference signal based on at least a reference signal correlated with the noise;
The reference signal generated by the reference signal generation unit, the error signal related to the sound collected by the first sound collection unit or the sound collected by the second sound collection unit, and the operation stability of the adaptive filter A filter coefficient updating unit that updates a filter coefficient of the adaptive filter using a step size parameter set when adjusting the characteristics;
A control signal generation unit that generates a control signal related to the first or second canceling sound by multiplying the reference signal by a filter coefficient of the adaptive filter;
With
The active noise suppression system, wherein the step size parameter when the synthesized speech output mode is selected is set to a value smaller than that when the cancellation output mode is selected. The active noise suppression system according to claim 3,
The active noise suppression device is:
When the synthesized speech output mode is selected, a value greater than 0 and less than 1 is set as the gain coefficient, while when the muting output mode is selected, 0 is set as the gain coefficient.
The active noise suppression system, wherein the switching of the voice output mode from one of the synthesized voice output mode or the cancellation sound output mode to the other is performed with a predetermined time constant. A first sound collection unit that is provided in a front seat space in a vehicle interior and collects sound generated in the front seat space;
A second sound collecting unit that is provided in the rear seat space in the room and collects sound generated in the rear seat space;
A first audio output unit provided in the front seat space for outputting audio;
A second audio output unit provided in the rear seat space for outputting audio;
An active noise suppression device that performs control to output a cancellation sound for suppressing noise in the room from at least one of the first audio output unit and the second audio output unit, and the noise An active noise suppression system for a vehicle that actively suppresses
The active noise suppression device is:
The first sound that is generated by referring to the noise and the sound collected by the first sound collection unit is combined with the sound collected by the second sound collection unit. A first speech synthesizer for generating synthesized speech;
Second sound obtained by synthesizing the sound collected by the first sound collection unit with the second canceling sound generated with reference to the noise and the sound collected by the second sound collection unit A second speech synthesizer for generating synthesized speech,
Performing control to output the second synthesized voice to the second voice output unit while outputting the first synthesized voice to the first voice output unit;
When generating the first and second synthesized voices, from the voice collected by the first sound collection unit and the voice collected by the second sound collection unit, An active noise suppression system for a vehicle, which performs a process of removing a voice component belonging to a frequency band related to noise.