Voice acquisition device

Abstract

To provide a sound acquisition device which can input the vibration sound of a vehicle with high coherence and diffusive noise to a noise microphone in order to enhance the effect of reducing the diffusive noise mixed in an utterance microphone.SOLUTION: An utterance microphone 12 is installed in an OHC 708 that is arranged on a passenger compartment 71 side with respect to a vehicle frame 701 and is fixed to the vehicle frame 701. A noise microphone 20 is installed in the vehicle frame 701 in a manner to be covered by the OHC 708. Since each microphone 12, 20 is installed in this way, it is easy for the noise microphone 20 to acquire the vibration sound 70b of the vehicle 70 and it is possible to install the noise microphone 20 in the vicinity of the utterance microphone 12. Therefore, it is possible to input the vibration sound 70b of the vehicle 70 with high coherence and diffusive noise mixed in the utterance microphone 12 into the noise microphone 20.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a voice acquisition device for a voice recognition system.

Background Art

[0002] As this type of voice acquisition device, for example, a noise reduction circuit described in Patent Document 1 has been conventionally known. The noise reduction circuit described in Patent Document 1 performs noise removal using an adaptive filter.

[0003] Specifically, the noise reduction circuit of Patent Document 1 includes a microphone for voice capture that captures the voice of a speaker in the vehicle interior, a microphone for noise capture installed in the vehicle interior, and a vibration sensor that acquires the vibration of the vehicle, which is a source of diffuse noise, installed outside the vehicle.

[0004] The noise reduction circuit estimates the diffuse noise in the vehicle interior based on the signal acquired by the noise capture microphone (or, in other words, the noise microphone) and the signal acquired by the vibration sensor. Then, the noise reduction circuit performs noise reduction by subtracting the signal indicating the estimated diffuse noise from the signal acquired by the voice capture microphone (or, in other words, the speech microphone).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When using a voice recognition system in a vehicle interior, background noise within the vehicle degrades the voice recognition accuracy. Examples of background noise include road noise, wind noise, air conditioning noise, and voices made by other people. These noises are input to the speech microphone along with the speaker's voice, significantly reducing the voice recognition accuracy of the voice recognition system.

[0007] In response to this, one method to prevent a decrease in speech recognition accuracy caused by noise inside the vehicle is acoustic signal processing using a microphone array with multiple microphones. This microphone array system performs signal processing on acoustic signals input from multiple microphones, reducing only the noise, thereby emphasizing and outputting the speaker's voice (i.e., the target voice).

[0008] In detail, microphone array systems reduce noise by utilizing the arrival time differences of multiple channels of acoustic signals. Therefore, for highly directional noise such as air conditioner wind noise and other people's voices (i.e., directional noise), a noise reduction effect can be expected from microphone array systems. On the other hand, for less directional noise such as driving noise and wind noise generated by the vibration of the entire vehicle (i.e., diffuse noise), the information necessary to separate the target voice from the diffuse noise, such as the arrival time differences of multiple channels of acoustic signals, becomes unclear. Therefore, for diffuse noise, the noise reduction effect of microphone array systems is lower compared to that of directional noise.

[0009] Therefore, it is conceivable to use the noise reduction circuit described in Patent Document 1 to reduce diffuse noise through adaptive filtering. In order to enhance the effect of adaptive filtering on reducing diffuse noise, it is necessary to acquire a signal that does not contain the target speech and has high coherence with the diffuse noise mixed into the speech microphone using a noise microphone, and to use this as the input signal for the adaptive filter. Furthermore, since there are many early reflections, reverberations, and sound propagation paths inside the vehicle, it is necessary to bring the distance between the speech microphone and the noise microphone close in order to increase the above coherence.

[0010] However, Patent Document 1 does not specify the installation position of each microphone. Therefore, if a speech microphone and a noise microphone are installed according to the description in Patent Document 1, and the distance between the two microphones increases, the coherence decreases, and the effect of reducing diffuse noise decreases. The inventors found this to be the result of a detailed study.

[0011] In view of the above, the present invention aims to provide a voice acquisition device that can input vehicle vibration noise, which has high coherence to diffuse noise, into a noise microphone in order to enhance the effect of reducing diffuse noise mixed into the speech microphone. [Means for solving the problem]

[0012] To achieve the above objective, the voice acquisition device described in claim 1 is: A voice acquisition device (10) for a voice recognition system, The voice (73a) of the speaker (72) inside the vehicle compartment (71) Includes primary audio (73) The microphone (12) for speech acquisition, This system acquires vibration noise (70b) from a vehicle (70), and includes a noise microphone (20) positioned to acquire vibration noise more easily than a speech microphone, making it more difficult to acquire the speaker's voice. 、 Multiple first noise reduction units (31) and Second noise reduction unit (32) and Equipped with, The speech microphone has multiple frame components (702, 702a) and is constructed by connecting multiple frame components to each other, and is positioned on the passenger compartment side relative to the vehicle frame (701) that surrounds the passenger compartment. The noise microphone is installed on the nearest frame component (702a), which is the frame component closest to the speech microphone among multiple frame components, or on a component (38, 40) that is fixed to the nearest frame component on the vehicle interior side. 、 Multiple microphones are provided for speaking. Multiple first noise reduction units are provided corresponding to each of the multiple speech microphones, and based on the primary speech signal (S1v) obtained from the speech microphone and the acquired noise signal (Sn) obtained by the noise microphone and indicating noise including vibration noise, a secondary speech signal (S2v) is obtained in which the diffuse noise is reduced compared to the primary speech, thereby making the speaker's voice stand out. The second noise reduction unit obtains a third-order speech signal (S3v) that represents a third-order speech signal in which the speaker's voice is highlighted by reducing directional noise, which has a higher directionality than diffuse noise, compared to the second-order speech, based on the respective second-order speech signals obtained by the multiple first noise reduction units.

[0013] In this way, the noise microphone can easily acquire vehicle vibration noise and can be placed in close proximity to the speech microphone. This makes it possible to input vehicle vibration noise, which has high coherence with diffuse noise mixed in with the speech microphone, into the noise microphone.

[0014] In addition, in some cases, each element in the application documents may be denoted by a reference numeral in parentheses. In this case, the reference numeral merely indicates one example of the correspondence between the element and the specific configuration described in the embodiments described later. Therefore, the present invention is not limited in any way by the notation of reference numerals. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram showing an excerpt of the location and surrounding area of ​​a vehicle equipped with a voice acquisition device in the first embodiment. [Figure 2] This is a schematic cross-sectional view showing the general configuration of the voice acquisition device in the first embodiment. [Figure 3] This is a block diagram showing the electrical system of the voice acquisition device according to the first embodiment. [Figure 4]A perspective view in the IV direction of FIG. 2, which is a schematic view showing an extract of an electric substrate, a speech microphone, and a noise microphone. [Figure 5] In a comparative example compared with the first embodiment, it is a figure corresponding to a figure extracting a sound-absorbing material and its peripheral part from FIG. 2. [Figure 6] In the second embodiment, it is a figure showing a sound-absorbing material included in a voice acquisition device and its peripheral part, and is a figure corresponding to FIG. 5. [Figure 7] In the third embodiment, it is a cross-sectional view schematically showing a schematic configuration of a voice acquisition device, and is a figure corresponding to FIG. 2. <{ [Figure 8] A perspective view schematically showing a sound-absorbing material included in the voice acquisition device of the third embodiment alone. [Figure 9] In the fourth embodiment, it is a cross-sectional view schematically showing a schematic configuration of a voice acquisition device, and is a figure corresponding to FIG. 2. [Figure 10] In the fifth embodiment, it is a cross-sectional view schematically showing a schematic configuration of a voice acquisition device, and is a figure corresponding to FIG. 2. [Figure 11] A perspective view in the XI direction of FIG. 10 in the fifth embodiment, which is a schematic view showing an extract of an electric substrate, a speech microphone, and a noise microphone. [Figure 12] A cross-sectional view showing the XII-XII cross-section of FIG. 11.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, each embodiment will be described while referring to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings.

[0017] (First Embodiment) As shown in Figures 1 to 3, the voice acquisition device 10 of this embodiment is used in a voice recognition system 77 mounted on a vehicle 70. The voice recognition system 77 is a system that acquires the voice 73a of a predetermined speaker 72 and recognizes that voice 73a. The voice recognition system 77 has a voice acquisition device 10 and a voice recognition engine 78. The voice acquisition device 10 acquires the voice 73a of a speaker 72, for example, the driver, who is seated in a predetermined position in the passenger compartment 71, and outputs a sound signal with noise reduced from the acquired sound to the voice recognition engine 78. Therefore, the voice acquisition device 10 of this embodiment may also be called a noise reduction device that reduces noise from the acquired sound which is a mixture of the speaker's voice 73a and noise.

[0018] The speech recognition engine 78 is a type of electronic control device and has the configuration of an in-vehicle microcomputer equipped with a CPU, RAM, ROM, non-volatile rewritable memory, etc. (not shown). In other words, the speech recognition engine 78 reads and executes a computer program stored in the ROM or non-volatile rewritable memory, which is a non-transitional physical recording medium. When this computer program is executed, the method corresponding to the computer program is executed. The electrical circuit section 30, which will be described later, also has the configuration of such an electronic control device.

[0019] The speech recognition engine 78 recognizes the speech information indicated by the speaker's voice 73a based on the speech signal acquired from the speech acquisition device 10. The speech recognition engine 78 then outputs a control signal corresponding to the recognized speech information to an external in-vehicle device, such as a navigation system or an air conditioning system.

[0020] In Figure 1 and Figure 4 (described later), the double-ended arrows indicate the orientation of the vehicle 70 on which the voice acquisition device 10 is mounted. Specifically, in Figure 1, the vehicle's longitudinal direction D1 and its vertical direction D2 are indicated by double-ended arrows, while in Figure 4 (described later), the vehicle's lateral direction D3 (or, in other words, its width direction D3) is indicated by double-ended arrows. These directions D1, D2, and D3 intersect each other, or more precisely, are perpendicular to each other.

[0021] Furthermore, in this description of the embodiment, the front side in the vehicle's longitudinal direction D1 is also referred to as the vehicle's front side, and the rear side in the vehicle's longitudinal direction D1 is also referred to as the vehicle's rear side. Also, the upper side in the vehicle's vertical direction D2 is also referred to as the vehicle's upper side, and the lower side in the vehicle's vertical direction D2 is also referred to as the vehicle's lower side. Also, the left side in the vehicle's left-right direction D3 is also referred to as the vehicle's left side, and the right side in the vehicle's left-right direction D3 is also referred to as the vehicle's right side.

[0022] As shown in Figures 1 and 2, the vehicle 70 of this embodiment is, for example, a passenger car and comprises a vehicle frame 701, an outer panel 705, interior materials 707, and an overhead console 708. The vehicle frame 701 forms the skeleton of the vehicle 70 and surrounds the passenger compartment 71. The vehicle frame 701 has a plurality of structural members, which are frame components 702, and is constructed by connecting these frame components 702 to each other. For example, the frame components 702 are connected to each other by welding, bolting, etc. In the description of this embodiment, the overhead console 708 may be abbreviated as OHC708.

[0023] The outer panel 705 forms the outer shell of the vehicle 70 and is made of, for example, a metal or resin plate. The outer panel 705 is positioned on the opposite side of the vehicle frame 701 from the passenger compartment 71 side (i.e., the side opposite the passenger compartment). Therefore, the outer panel 705 faces the external space 70a, which is the space outside the vehicle. The outer panel 705 is positioned with a gap between it and the vehicle frame 701 and is fixed to the vehicle frame 701 by being partially connected to it. Methods for fixing the outer panel 705 to the vehicle frame 701 include, for example, welding, bolting, and adhesive.

[0024] The interior material 707 is made of, for example, a resin plate and is positioned on the passenger compartment 71 side relative to the vehicle frame 701. Therefore, the interior material 707 faces the passenger compartment 71. In other words, the interior material 707 is positioned to separate the vehicle frame 701 from the passenger compartment 71. Furthermore, the interior material 707 is positioned with a gap between it and the vehicle frame 701 and is fixed to the vehicle frame 701 by being partially connected to it. Methods for fixing the interior material 707 to the vehicle frame 701 include, for example, snap fitting, adhesive, and screw fastening.

[0025] The OHC708 is an interior product installed in the ceiling area between the driver's and passenger's seats, primarily responsible for interior lighting. Depending on the vehicle model, the OHC708 may also include functions such as a storage compartment, sunroof opening / closing, emergency call button, and hands-free phone switch. The OHC708 is made of, for example, resin. The OHC708 is positioned on the passenger compartment side of the vehicle frame 701 and is fixed to the vehicle frame 701 by screws, snap-fits, etc. For example, the OHC708 is positioned on the upper side in the vehicle direction relative to the passenger compartment 71 and is fitted into a hole 707a formed in the interior material 707. The passenger compartment 71 side of the OHC708 is exposed to the passenger compartment 71.

[0026] As shown in Figures 2 to 4, the voice acquisition device 10 comprises multiple speech microphones 12, an electrical circuit board 16, a noise microphone 20, sound-absorbing material 24, and an electrical circuit section 30. Note that in Figure 4, the OHC 708 and sound-absorbing material 24 are not shown.

[0027] The speech microphone 12 and the noise microphone 20 each convert the acquired sound into an electrical signal and output that electrical signal to the electrical circuit section 30 configured on the electrical circuit board 16. For example, both the speech microphone 12 and the noise microphone 20 are omnidirectional microphones.

[0028] Since the noise microphone 20 is positioned away from the electrical circuit board 16, it is electrically connected to the electrical circuit board 16 via the wire 17. Furthermore, the analog signals output from each microphone 12 and 20 are converted, for example, to digital signals before being input to the electrical circuit section 30.

[0029] Each of the multiple speech microphones 12 is a microphone that acquires the voice 73a (in other words, the speaker's voice 73a) of the speaker 72 inside the vehicle compartment 71. That is, the target sound that the speech microphones 12 aim to acquire is the speaker's voice 73a. Specifically, in addition to the speaker's voice 73a, the speech microphones 12 also receive the room noise 73b, which is background noise inside the vehicle compartment 71. Therefore, it can be said that the speech microphones 12 acquire a primary voice 73 that includes both the speaker's voice 73a and the room noise 73b. The multiple speech microphones 12 together constitute a microphone array.

[0030] The interior noise 73b consists of diffuse noise and directional noise, which has a higher degree of directionality than diffuse noise. Diffuse noise is low-directional noise such as driving noise and wind noise generated by the vibration of the entire vehicle 70. Directional noise is high-directional noise such as the voices of others other than the speaker 72 and the wind noise from the air conditioning system.

[0031] Specifically, the vibration noise 70b of the vehicle 70, which arises from the vibration 701a of the vehicle frame 701, is the main source of the diffuse noise described above. In other words, the main component of the diffuse noise contained in the interior noise 73b is the vibration noise 70b of the vehicle 70. This vibration noise 70b of the vehicle 70 enters the interior of the vehicle compartment 71, for example, by passing through the interior material 707 from the side opposite the vehicle compartment.

[0032] The electrical circuit board 16 is a flat printed circuit board constructed from a resin plate as a base material, and multiple circuit patterns are formed on the electrical circuit board 16. The electrical circuit board 16 is fixed to the OHC 708 by screws or the like. In other words, the electrical circuit board 16 is fixed to the vehicle frame 701 via the OHC 708. Therefore, the electrical circuit board 16 is positioned on the passenger compartment 71 side with a gap between it and the vehicle frame 701. In this embodiment, the OHC 708 functions as a support for the electrical circuit board 16 and the components mounted on the electrical circuit board 16.

[0033] In detail, the electrical circuit board 16 is fixed via an OHC 708 to the nearest frame component 702a, which is the frame component closest to the speech microphone 12 among all the frame components 702 of the vehicle frame 701. The electrical circuit board 16 is then positioned on the passenger compartment 71 side, spaced apart from the nearest frame component 702a.

[0034] The electrical circuit board 16 has one surface 161 located on one side of the electrical circuit board 16 in the direction normal to the circuit board 16 (i.e., the circuit board normal direction Dsb) and facing away from the passenger compartment, and another surface 162 located on the other side of the direction normal to the circuit board 16 and facing towards the passenger compartment 71. That is, one surface 161 of the electrical circuit board 16 faces the vehicle frame 701. And one surface 161 of the electrical circuit board 16 faces the vehicle frame 701 at a distance. That is, the vehicle frame 701 has a frame-facing portion 701b as part of the vehicle frame 701 that faces the one surface 161 of the electrical circuit board 16 at a distance in the direction normal to the circuit board Dsb. In this embodiment, the frame-facing portion 701b is part of the nearest frame component 702a.

[0035] Furthermore, the substrate normal direction Dsb is also the normal direction of one surface 161 and the normal direction of the other surface 162. In addition, one side of the substrate normal direction Dsb may be called the side opposite the vehicle compartment of the substrate normal direction Dsb, and the other side of the substrate normal direction Dsb may be called the side of the vehicle compartment 71 of the substrate normal direction Dsb.

[0036] Multiple speech microphones 12 are arranged in a row with some spacing between them on one side 161 of the electrical circuit board 16. Each of these multiple speech microphones 12 is mounted on one side 161 of the electrical circuit board 16. In other words, since the multiple speech microphones 12 are fixed to the OHC 708 via the electrical circuit board 16 as described above, it can be said that the multiple speech microphones 12 are installed on the OHC 708. What is meant by "the multiple speech microphones 12 are installed on the OHC 708" is, in other words, that the multiple speech microphones 12 are positioned in close proximity to the OHC 708 and are fixed to the OHC 708.

[0037] The multiple speech microphones 12 mounted on the electrical circuit board 16 are positioned on the passenger compartment side of the vehicle frame 701, spaced apart from each other.

[0038] Furthermore, the electrical circuit board 16 has multiple sound holes 16a that penetrate through it. Each of these sound holes 16a is a hole for guiding the primary sound 73 from inside the vehicle compartment 71 to the speech microphone 12. Therefore, the multiple sound holes 16a are provided in a one-to-one correspondence with each of the multiple speech microphones 12. For example, in this embodiment, eight speech microphones 12 are provided, so eight sound holes 16a are formed on the electrical circuit board 16.

[0039] Each of the multiple sound holes 16a has one end 16b provided on one side in the direction Dsb normal to the substrate, and the other end 16c provided on the other side in the direction Dsb normal to the substrate. Each of the multiple sound holes 16a is positioned so as to overlap the other side in the direction Dsb normal to the substrate with respect to the speech microphone 12. Therefore, one end 16b of the sound hole 16a opens toward the speech microphone 12, and the other end 16c of the sound hole 16a opens toward the opposite side from the vehicle frame 701 and is open to the passenger compartment 71. With the sound holes 16a provided in this way, the primary sound 73 is transmitted from inside the passenger compartment 71 through the sound holes 16a to each of the multiple speech microphones 12.

[0040] The noise microphone 20 is a microphone that acquires the vibration sound 70b of the vehicle 70. Although most of the noise acquired by the noise microphone 20 is the vibration sound 70b of the vehicle 70, the noise acquired by the noise microphone 20 also contains some sounds other than the vibration sound 70b of the vehicle 70, such as the speaker's voice 73a.

[0041] The noise microphone 20 is positioned on the passenger compartment side of the vehicle frame 701 to facilitate the acquisition of vibration sounds 70b from the vehicle 70, and is fixed to the vehicle frame 701 by means of screws or adhesive, for example, while in contact with the vehicle frame 701. Since the noise microphone 20 is fixed to the vehicle frame 701 in this way, in other words, it can be said that the noise microphone 20 is installed on the vehicle frame 701. What is meant here by "the noise microphone 20 is installed on the vehicle frame 701" is, in other words, that the noise microphone 20 is positioned in close proximity to the vehicle frame 701 and is fixed to the vehicle frame 701.

[0042] Furthermore, in relation to the OHC708, the noise microphone 20 is positioned inside the OHC708. In other words, the noise microphone 20 is installed on the vehicle frame 701 so as to be covered by the OHC708.

[0043] Furthermore, the distance between the noise microphone 20 and the vehicle frame 701 is shorter than the distance between each of the speech microphones 12 and the vehicle frame 701. In terms of the positional relationship between the noise microphone 20 and the interior material 707, the noise microphone 20 is located on the side opposite the interior material 707 to the passenger compartment (in other words, on the side of the vehicle frame 701).

[0044] Furthermore, focusing on the multiple frame components 702, the noise microphone 20 is installed on the nearest frame component 702a among all the frame components 702 of the vehicle frame 701.

[0045] From a different perspective, the noise microphone 20 is positioned away from one side 161 of the electrical circuit board 16 and between that side 161 and the frame-facing portion 701b of the vehicle frame 701, and is installed on that frame-facing portion 701b. In short, the noise microphone 20 is fixed to that frame-facing portion 701b.

[0046] The sound-absorbing material 24 significantly attenuates sound passing through it. The sound-absorbing material 24 is made of a sound-absorbing material, such as sponge or foamed urethane. The sound-absorbing material 24 is positioned on the passenger compartment 71 side of the vehicle frame 701 and is fixed to the vehicle frame 701 by adhesive or the like.

[0047] Furthermore, an internal space 24a is formed inside the sound-absorbing material 24, and this internal space 24a is open only on the vehicle frame 701 side, with all other parts covered by the sound-absorbing material 24. The opening of the internal space 24a on the vehicle frame 701 side is blocked by the vehicle frame 701. The noise microphone 20 is placed in the internal space 24a of the sound-absorbing material 24 and is covered by the sound-absorbing material 24. In other words, the noise microphone 20 is placed in the internal space 24a of the sound-absorbing material 24, which is the space enclosed by the vehicle frame 701 and the sound-absorbing material 24. Therefore, the noise microphone 20 is positioned to be less likely to acquire speaker voice 73a and more likely to acquire vibration sound 70b of the vehicle 70 compared to all the speech microphones 12.

[0048] The sound-absorbing material 24 has an inner wall surface 24b that faces and surrounds the internal space 24a of the sound-absorbing material 24. The inner wall surface 24b of the sound-absorbing material 24 is formed so as not to include parallel surfaces that are parallel to each other across the internal space 24a. Specifically, the inner wall surface 24b of this embodiment does not include a flat portion and has a wave-like uneven structure, thereby being formed so as not to include the aforementioned parallel surfaces. Due to the unevenness of the inner wall surface 24b, standing waves are not generated, and sound is reflected multiple times and absorbed by the sound-absorbing material 24.

[0049] The electrical circuit section 30 shown in Figure 3 is composed of one or more electrical components, such as ICs and resistors, mounted on the electrical circuit board 16. This electrical circuit section 30 performs signal processing to obtain an audio signal from which room noise 73b has been reduced from the primary audio signal 73. Functionally, the electrical circuit section 30 has a plurality of first noise reduction sections 31 for obtaining an audio signal with reduced diffuse noise, and a second noise reduction section 32 for obtaining an audio signal with reduced directional noise.

[0050] Multiple first noise reduction units 31 are provided in a one-to-one correspondence with each of the multiple speech microphones 12. For example, in this embodiment, eight speech microphones 12 are provided, so the electrical circuit unit 30 has eight first noise reduction units 31. Since one speech microphone 12 and one first noise reduction unit 31 constitute one channel, eight channels are provided in this embodiment.

[0051] Specifically, each of the multiple first noise reduction units 31 receives a primary voice signal S1v representing the primary voice 73 from the speech microphone 12 corresponding to that first noise reduction unit 31. In addition, each of the multiple first noise reduction units 31 receives an acquired noise signal Sn from the noise microphone 20, which represents the acquired noise including the vibration sound 70b of the vehicle 70 acquired by the noise microphone 20.

[0052] Then, each of the multiple first noise reduction units 31 obtains a secondary speech signal S2v, which represents a secondary speech in which diffuse noise is reduced compared to the primary speech 73, based on the primary speech signal S1v and the acquired noise signal Sn. This secondary speech signal S2v is output from each of the multiple first noise reduction units 31 to the second noise reduction unit 32. In the secondary speech represented by the secondary speech signal S2v, since diffuse noise is reduced compared to the primary speech 73, the speaker's voice 73a is relatively more prominent in the secondary speech compared to the primary speech 73. In other words, the secondary speech represented by the secondary speech signal S2v is a sound in which the speaker's voice 73a is more prominent compared to the primary speech 73 due to the reduction of diffuse noise compared to the primary speech 73.

[0053] Each of the multiple first noise reduction units 31 has a variable FIR filter 311, an adder 312, and an adaptive algorithm execution unit 313 to obtain the secondary audio signal S2v. The "FIR" in the description of "variable FIR filter 311" is an abbreviation for "Finite Impulse Response".

[0054] The variable FIR filter 311 adjusts the sound pressure and phase of the acquired noise signal Sn and outputs the adjusted sound signal. The adder 312 receives the adjusted sound signal from the variable FIR filter 311 and the primary speech signal S1v from the speech microphone 12 as input. The adder 312 then inverts the adjusted sound signal from the variable FIR filter 311 and adds the inverted sound signal to the primary speech signal S1v. This added sound signal is the secondary speech signal S2v, which is output from the adder 312 to the adaptive algorithm execution unit 313 and the second noise reduction unit 32, respectively.

[0055] The adaptive algorithm execution unit 313 processes the secondary audio signal S2v output from the adder 312 using a predetermined adaptive algorithm and automatically updates the filter coefficients of the variable FIR filter 311. This update of the filter coefficients allows the variable FIR filter 311 to output an audio signal in which the speaker's voice 73a has been effectively removed from the noise acquired by the noise microphone 20. The adaptive algorithm executed by the adaptive algorithm execution unit 313 may be, for example, the LMS algorithm or the RLS algorithm. "LMS" stands for "Least mean square," and "RLS" stands for "Recursive least square."

[0056] The second noise reduction unit 32 receives secondary speech signals S2v from each of the adders 312 of the multiple first noise reduction units 31. Based on these multiple secondary speech signals S2v, the second noise reduction unit 32 obtains a tertiary speech signal S3v, which represents a tertiary speech in which directional noise is reduced compared to the secondary speech. This tertiary speech signal S3v is output from the second noise reduction unit 32 to the speech recognition engine 78. The tertiary speech indicated by the tertiary speech signal S3v is a speech in which both directional noise and diffuse noise are reduced compared to the primary speech 73, so relatively speaking, the speaker's voice 73a is more prominent compared to the secondary speech. In other words, the tertiary speech indicated by the tertiary speech signal S3v is a sound in which the speaker's voice 73a is more prominent compared to the secondary speech due to the reduction of directional noise compared to the secondary speech.

[0057] For example, the second noise reduction unit 32 performs microphone array signal processing to reduce directional noise by utilizing the arrival time differences of multiple channel acoustic signals (specifically, multiple secondary audio signals S2v), thereby obtaining a tertiary audio signal S3v. For example, delay sum method or blind source separation may be employed as the microphone array signal processing.

[0058] In this way, the third-order speech signal S3v, in which the speaker's voice 73a is highlighted by noise reduction, is input from the electrical circuit unit 30 to the speech recognition engine 78, thereby enabling the speech recognition engine 78 to improve the speech recognition rate of the speaker's voice 73a.

[0059] As described above, according to this embodiment, as shown in Figure 2, the speech microphone 12 is mounted on an OHC 708 which is positioned on the passenger compartment 71 side relative to the vehicle frame 701 and is fixed to the vehicle frame 701. The noise microphone 20 is mounted on the vehicle frame 701 so as to be covered by the OHC 708.

[0060] Alternatively, the speech microphone 12 is positioned on the passenger compartment 71 side relative to the vehicle frame 701. The noise microphone 20 is installed on the nearest frame component 702a among the multiple frame components 702 that make up the vehicle frame 701.

[0061] Furthermore, from a different perspective, the electrical circuit board 16 has a speech microphone 12 mounted on it, and the electrical circuit board 16 has one surface 161 that faces the frame-facing portion 701b, which is part of the nearest frame component 702a. The noise microphone 20 is positioned away from the surface 161 of the electrical circuit board 16 and between that surface 161 and the frame-facing portion 701b, and is installed on the frame-facing portion 701b.

[0062] In this manner, the microphones 12 and 20 are installed in a way that makes it easy for the noise microphone 20 to acquire the vibration sound 70b of the vehicle 70, and allows the noise microphone 20 to be installed in a position close to the speech microphone 12. Furthermore, within the constraint that the noise microphone 20 must be able to acquire the vibration sound 70b of the vehicle 70, the noise microphone 20 can be installed in a position close to the speech microphone 12.

[0063] Therefore, it is possible to input the vibration sound 70b of the vehicle 70, which has high coherence with the diffuse noise mixed into the speech microphone 12, into the noise microphone 20. By using the vibration sound 70b of the vehicle 70 acquired by the noise microphone 20, the amount of diffuse noise reduction in the first noise reduction unit 31 can be increased. In other words, the effect of reducing the diffuse noise mixed into the speech microphone 12 can be enhanced.

[0064] (1) In addition, according to this embodiment, the sound-absorbing material 24 is positioned on the passenger compartment 71 side relative to the vehicle frame 701. The sound-absorbing material 24 has an internal space 24a that is open on the vehicle frame 701 side, which is formed inside the sound-absorbing material 24. The noise-reducing microphone 20 is positioned in the internal space 24a of the sound-absorbing material 24 and is surrounded by the sound-absorbing material 24.

[0065] Therefore, compared to a case where, for example, no sound-absorbing material 24 is provided, it is possible to prevent the speaker's voice 73a from being mixed into the noise acquired by the noise microphone 20. Furthermore, the amount of reduction of diffuse noise by the first noise reduction unit 31 can be increased. As a result, the speaker's voice 73a can be made more prominent in the secondary speech indicated by the secondary speech signal S2v output from the first noise reduction unit 31, and consequently, the speech recognition rate of the speaker's voice 73a by the speech recognition engine 78 can be increased.

[0066] In the noise reduction circuit described in Patent Document 1, a vibration sensor is provided in addition to the noise-capturing microphone. In contrast, in this embodiment, the mixing of the speaker's voice 73a with the noise acquired by the noise-capturing microphone 20 is suppressed by the sound-absorbing material 24, making it possible to eliminate the need for a sensor equivalent to the vibration sensor in Patent Document 1. This makes it possible to reduce the cost of the voice acquisition device 10, for example.

[0067] (2) Furthermore, according to this embodiment, the sound-absorbing material 24 has an inner wall surface 24b that faces the internal space 24a of the sound-absorbing material 24 and surrounds the internal space 24a. The inner wall surface 24b of the sound-absorbing material 24 is formed so as not to include parallel surfaces that are parallel to each other with respect to the internal space 24a.

[0068] Now, let's consider the comparative example shown in Figure 5. The sound-absorbing material 25 in the comparative example in Figure 5 corresponds to the sound-absorbing material 24 of the first embodiment. Also, the internal space 25a of the sound-absorbing material 25 in the comparative example corresponds to the internal space 24a of the sound-absorbing material 24 of the first embodiment, and the inner wall surface 25b of the sound-absorbing material 25 in the comparative example corresponds to the inner wall surface 24b of the sound-absorbing material 24 of the first embodiment. In the comparative example in Figure 5, the sound-absorbing material 25 is different from that of the first embodiment, while everything else is the same as in the first embodiment.

[0069] In the comparative example in Figure 5, the inner wall surface 25b of the sound-absorbing material 25 includes parallel surfaces that are parallel to each other across the internal space 25a. For example, the inner wall surface 25b includes parallel surfaces that are parallel to the wall surface of the vehicle frame 701 that faces the internal space 25a. As a result, sound reflection occurs repeatedly on these parallel surfaces as shown by arrows A1 and A2, generating standing waves in the sound-absorbing material 25. Consequently, in the comparative example in Figure 5, the frequency characteristics of the noise acquired by the noise microphone 20 change, and the noise reduction effect of the first noise reduction unit 31 (see Figure 3) decreases.

[0070] In contrast, as described above, the inner wall surface 24b of the sound-absorbing material 24 in this embodiment is formed so as not to include parallel surfaces that are parallel to each other across the internal space 24a, so that standing waves are less likely to be generated by the sound-absorbing material 24. Therefore, it is possible to prevent the frequency characteristics of the noise acquired by the noise microphone 20 from changing due to the generation of standing waves within the sound-absorbing material 24, and to prevent a decrease in the noise reduction effect caused by the generation of standing waves by the sound-absorbing material 24.

[0071] (3) Furthermore, according to this embodiment, as shown in Figures 2 and 3, each of the multiple first noise reduction units 31 obtains a secondary audio signal S2v, which represents a secondary audio signal in which diffuse noise is reduced compared to the primary audio signal 73, based on the primary audio signal S1v and the acquired noise signal Sn. The second noise reduction unit 32 then obtains a tertiary audio signal S3v, which represents a tertiary audio signal in which directional noise is reduced compared to the above secondary audio signal, based on the respective secondary audio signals S2v obtained by the multiple first noise reduction units 31.

[0072] Therefore, the third-order speech signal S3v input to the speech recognition engine 78 has both directional and diffuse noise reduced compared to the primary speech signal 73, resulting in a signal where the speaker's speech 73a is more prominent. As a result, the speech recognition rate of the speaker's speech 73a by the speech recognition engine 78 can be increased.

[0073] Furthermore, according to this embodiment, as shown in Figure 2, the noise reduction microphone 20 is positioned on the passenger compartment 71 side relative to the vehicle frame 701, and on the opposite side of the passenger compartment (in other words, on the vehicle frame 701 side) relative to the interior material 707. Therefore, the speaker's voice 73a directed towards the noise reduction microphone 20 is absorbed by the interior material 707, making it possible for the interior material 707 to suppress the mixing of the speaker's voice 73a with the noise acquired by the noise reduction microphone 20. As a result, the amount of noise reduction in the first noise reduction unit 31 is increased.

[0074] (Second Embodiment) Next, a second embodiment will be described. In this embodiment, the differences from the first embodiment described above will be mainly explained. Furthermore, parts that are the same as or equivalent to the above embodiment will be omitted or simplified in their description. The same applies to the descriptions of the embodiments described later.

[0075] As shown in Figure 6, in this embodiment as in the first embodiment, the inner wall surface 24b of the sound-absorbing material 24 is formed so as not to include parallel surfaces that are parallel to each other across the internal space 24a. However, in this embodiment, the shape of the inner wall surface 24b of the sound-absorbing material 24 is different from that of the first embodiment.

[0076] Specifically, in a cross-section perpendicular to the inner wall surface 24b of the sound-absorbing material 24 (i.e., the cross-section in Figure 6), the inner wall surface 24b is constructed by connecting multiple planar portions so that the internal space 24a of the sound-absorbing material 24 is triangular in shape.

[0077] Except as described above, this embodiment is the same as the first embodiment. In this embodiment, the effects obtained from the configuration common to the first embodiment can be obtained in the same way as in the first embodiment.

[0078] (Third embodiment) Next, a third embodiment will be described. This embodiment will primarily describe the differences from the first embodiment described above.

[0079] As shown in Figures 7 and 8, the shape of the sound-absorbing material 24 in this embodiment differs from that of the first embodiment.

[0080] Specifically, the sound-absorbing material 24 is formed to surround the noise microphone 20 all around when viewed in a direction along the normal direction of the mounting surface 701c of the vehicle frame 701 on which the noise microphone 20 is installed (for example, in the direction indicated by arrow A3). In this respect, this embodiment is the same as the first embodiment.

[0081] However, unlike the first embodiment, in this embodiment the sound-absorbing material 24 has a shape in which its internal space 24a is open to the opposite side from the vehicle frame 701 side (i.e., the passenger compartment 71 side). Therefore, when the sound-absorbing material 24 of this embodiment is viewed on its own, it has a cylindrical shape, and the internal space 24a of the sound-absorbing material 24 is open at both ends of the cylindrical shape.

[0082] Furthermore, the electrical circuit board 16 is positioned at a distance from the opening 24c on the passenger compartment 71 side of the internal space 24a of the sound-absorbing material 24, and overlaps the opening 24c. The opening 24c of the sound-absorbing material 24 is located closer to the vehicle frame 701 than the interior material 707.

[0083] Therefore, the path through which the speaker's voice 73a passes through the opening 24c of the sound-absorbing material 24 to the noise microphone 20 is obstructed to some extent by the electrical circuit board 16 and the interior material 707. Accordingly, in this embodiment as in the first embodiment, the noise microphone 20 is positioned to make it more difficult to acquire the speaker's voice 73a and to make it easier to acquire the vibration noise 70b of the vehicle 70 compared to all the speech microphones 12. In this embodiment, since the sound-absorbing material 24 is in contact with the OHC 708 on the passenger compartment 71 side, the opening 24c of the sound-absorbing material 24 on the passenger compartment 71 side is blocked by the OHC 708.

[0084] (1) As described above, according to this embodiment, the sound-absorbing material 24 is formed to surround the noise microphone 20 when viewed in a direction along the normal direction of the mounting surface 701c of the vehicle frame 701. The sound-absorbing material 24 has an internal space 24a that opens to the opposite side from the vehicle frame 701 (i.e., to the passenger compartment 71 side).

[0085] Therefore, the sound-absorbing material 24 creates a directivity in the noise microphone 20 that is directed towards the speech microphone 12. As a result, compared to the case where the vehicle compartment 71 side of the internal space 24a is blocked by the sound-absorbing material 24, the noise microphone 20 can acquire a sound with higher coherence than the diffuse noise acquired by the speech microphone 12. Consequently, the amount of noise reduction in the first noise reduction unit 31 can be increased.

[0086] Except as described above, this embodiment is the same as the first embodiment. In this embodiment, the effects obtained from the configuration common to the first embodiment can be obtained in the same way as in the first embodiment.

[0087] Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with the second embodiment described above.

[0088] (Fourth Embodiment) Next, a fourth embodiment will be described. This embodiment will primarily describe the differences from the first embodiment described above.

[0089] As shown in Figure 9, the voice acquisition device 10 of this embodiment includes a vibration-damping material 36, a noise-reducing microphone case 37, and a noise-reducing microphone circuit board 38. These vibration-damping material 36, noise-reducing microphone case 37, and noise-reducing microphone circuit board 38 are placed inside the OHC 708 and covered by the OHC 708. Note that the voice acquisition device 10 of this embodiment does not include a sound-absorbing material 24 (see Figure 2).

[0090] The vibration-damping material 36 is made of an elastic material such as rubber or foamed urethane that easily absorbs vibrations. The vibration-damping material 36 is positioned on the passenger compartment 71 side of the vehicle frame 701 and is fixed to the vehicle frame 701 in contact with it. The vibration-damping material 36 is formed in the shape of a plate that extends along the surface of the vehicle frame 701 that the vibration-damping material 36 contacts.

[0091] The noise-reducing microphone case 37 is a resin or metal housing that houses the noise-reducing microphone 20 and the noise-reducing microphone circuit board 38. The noise-reducing microphone case 37 is positioned on the passenger compartment 71 side relative to the vehicle frame 701. The noise-reducing microphone case 37 is fixed to the vehicle frame 701, for example by screws, with a vibration-damping material 36 sandwiched between it and the vehicle frame 701. In other words, the noise-reducing microphone case 37 does not directly contact the vehicle frame 701, but is fixed to the vehicle frame 701 via the vibration-damping material 36.

[0092] Furthermore, the noise-reducing microphone case 37 has multiple through-holes 37a that connect the inside and outside of the noise-reducing microphone case 37.

[0093] The noise-reducing microphone circuit board 38 is a flat printed circuit board constructed from a resin plate as its base material, and multiple circuit patterns are formed on the noise-reducing microphone circuit board 38. Although the wires 17 (see Figure 2) are not shown in Figure 9, the noise-reducing microphone circuit board 38 is electrically connected to the electrical circuit board 16 by the wires 17.

[0094] A noise-reducing microphone 20 is mounted on the noise-reducing microphone circuit board 38, and the noise-reducing microphone circuit board 38 is fixed to the noise-reducing microphone case 37. Therefore, the noise-reducing microphone 20 is fixed to the vehicle frame 701 via the noise-reducing microphone circuit board 38, the noise-reducing microphone case 37, and the vibration-damping material 36.

[0095] In this embodiment as well, the noise microphone 20 is positioned close to the nearest frame component 702a and fixed to the nearest frame component 702a, so it can be said that the noise microphone 20 is installed on the nearest frame component 702a. Furthermore, since the noise microphone 20 is mounted on the noise microphone circuit board 38, it can also be said that it is installed on the noise microphone circuit board 38, which is a component fixed to the vehicle compartment 71 side relative to the nearest frame component 702a.

[0096] Furthermore, the noise microphone substrate 38 has a through-hole 38a formed through it. One end of the through-hole 38a faces the noise microphone 20, and the other end faces the inner wall surface of the noise microphone case 37, where multiple case through-holes 37a are formed.

[0097] Therefore, the vibration noise 70b (see Figure 2) from the vehicle 70 reaches the noise microphone 20 through multiple case through-holes 37a and circuit board through-holes 38a from the vehicle frame 701, as indicated by arrows B1 and B2.

[0098] In this embodiment, the multiple case through-holes 37a are located on the passenger compartment 71 side of the noise microphone case 37, but the electrical circuit board 16 is positioned with spacing between the multiple case through-holes 37a so as to cover all of them. Furthermore, the multiple case through-holes 37a are located on the vehicle frame 701 side of the interior material 707.

[0099] Therefore, the path through which the speaker's voice 73a reaches the noise microphone 20 via the case through-hole 37a is obstructed to some extent by the electrical circuit board 16 and the interior material 707. Accordingly, in this embodiment as in the first embodiment, the noise microphone 20 is positioned to make it more difficult to acquire the speaker's voice 73a and to make it easier to acquire the vibration sound 70b of the vehicle 70 compared to all the speech microphones 12.

[0100] (1) As described above, according to this embodiment, the noise microphone 20 is fixed to the vehicle frame 701 via a vibration-damping material 36. Therefore, the noise microphone 20 can be positioned close to the vehicle frame 701. Compared to the case in which the noise microphone 20 is directly attached to the vehicle frame 701, for example, the vibration-damping material 36 can suppress the vibration of the noise microphone 20 in accordance with the vibration 701a (see Figure 2) of the vehicle frame 701. Therefore, it is possible to prevent the frequency characteristics of the noise acquired by the noise microphone 20 from changing due to the vibration of the noise microphone 20.

[0101] Except as described above, this embodiment is the same as the first embodiment. In this embodiment, the effects obtained from the configuration common to the first embodiment can be obtained in the same way as in the first embodiment.

[0102] (Fifth embodiment) Next, a fifth embodiment will be described. This embodiment will primarily describe the differences from the first embodiment described above.

[0103] As shown in Figures 10 to 12, the electrical circuit board 16 is equipped with multiple speech microphones 12 as well as a noise microphone 20. The voice acquisition device 10 includes a microphone support member 40 which includes the electrical circuit board 16. In these respects, this embodiment differs from the first embodiment. In this embodiment, the voice acquisition device 10 does not have the sound-absorbing material 24 shown in Figure 2, but sound-absorbing material may be provided on the inner wall of the noise microphone 20 case.

[0104] Specifically, in this embodiment, multiple speech microphones 12 are mounted on one side 161 of the electrical circuit board 16. In addition, a noise microphone 20 is also mounted on the same side 161 of the electrical circuit board 16. For example, the noise microphone 20 is positioned on the side 161 of the electrical circuit board 16, away from each of the multiple speech microphones 12. In this embodiment, since the noise microphone 20 is mounted on the electrical circuit board 16, the wires 17 shown in Figure 2 are unnecessary.

[0105] The microphone support member 40 comprises an electrical circuit board 16, a first laminate 41, and a second laminate 42. The first laminate 41 and the second laminate 42 are, for example, resin plates and are formed in a flat shape with thickness in the same direction as the thickness direction of the electrical circuit board 16. The electrical circuit board 16, the first laminate 41, and the second laminate 42 are fixed to each other, for example by adhesive or screws, so that they form an integrated structure.

[0106] The microphone support member 40 is fixed to the OHC 708 by screws or the like. In other words, the microphone support member 40 is fixed to the vehicle frame 701 via the OHC 708. Therefore, the microphone support member 40 is positioned on the passenger compartment 71 side with a gap between it and the vehicle frame 701. This microphone support member 40 is configured as a microphone board for supporting each microphone 12, 20 against the vehicle frame 701.

[0107] In this embodiment as well, the noise microphone 20 is positioned close to the nearest frame component 702a and fixed to the nearest frame component 702a, so it can be said that the noise microphone 20 is installed on the nearest frame component 702a. Furthermore, since the noise microphone 20 is mounted on the electrical circuit board 16, it can also be said that it is installed on the electrical circuit board 16, which is a component fixed to the nearest frame component 702a on the vehicle compartment 71 side. And, as described above, the microphone support member 40 has its electrical circuit board 16, so it can also be said that the noise microphone 20 is installed on the microphone support member 40, which is a component fixed to the nearest frame component 702a on the vehicle compartment 71 side.

[0108] The first laminate 41 is laminated to the electrical substrate 16 on the other side 162 of the electrical substrate 16, and is in close contact with the other side 162 of the electrical substrate 16, for example. The second laminate 42 is laminated to the electrical substrate 16 on the other side 162 of the electrical substrate 16, with the first laminate 41 in between, and is in close contact with the first laminate 41, for example.

[0109] Furthermore, the microphone support member 40 has multiple sound holes 40a for voice and multiple sound holes 40e for noise. As a result, the microphone support member 40 has the configuration of an acoustic tube. That is, as an acoustic tube, the microphone support member 40 guides the speaker's voice 73a from inside the vehicle compartment 71 through the respective sound holes 40a to the multiple speech microphones 12. At the same time, the microphone support member 40 guides the vibration sound 70b of the vehicle 70 from the vehicle frame 701 side through the sound holes 40e to the noise microphone 20.

[0110] Each of the multiple sound holes 40a of the microphone support member 40 is formed as a through-hole that penetrates the microphone support member 40 in the direction Dsb normal to the substrate. That is, the sound holes 40a penetrate in a straight line through the electrical substrate 16, the first laminate 41, and the second laminate 42. Furthermore, the sound holes 40a of this embodiment include the sound holes 16a of the first embodiment (see Figure 2).

[0111] Each of the multiple sound holes 40a is a hole for guiding the primary sound 73 from inside the vehicle compartment 71 to the speech microphone 12. Therefore, the multiple sound holes 40a are provided in a one-to-one correspondence with each of the multiple speech microphones 12. For example, in this embodiment, eight speech microphones 12 are provided, so eight sound holes 40a are formed in the microphone support member 40.

[0112] Each of the multiple sound holes 40a has one end 40b provided on one side in the direction Dsb normal to the substrate, and the other end 40c provided on the other side in the direction Dsb normal to the substrate. Each of the multiple sound holes 40a is positioned so as to overlap the other side in the direction Dsb normal to the substrate with respect to the speech microphone 12. Therefore, one end 40b of the sound hole 40a opens toward the speech microphone 12, and the other end 40c of the sound hole 40a opens toward the opposite side from the vehicle frame 701 and is open to the passenger compartment 71. With the sound holes 40a provided in this way, the primary sound 73 is transmitted from inside the passenger compartment 71 through the sound holes 40a to each of the multiple speech microphones 12.

[0113] The noise-reducing sound hole 40e of the microphone support member 40 is a hole for guiding vibration noise 70b from the vehicle 70 on the vehicle frame 701 side relative to the electrical circuit board 16 to the noise microphone 20. This noise-reducing sound hole 40e is formed by bending within the microphone support member 40. The noise-reducing sound hole 40e has one end 40f and the other end 40g formed on one surface 161 of the electrical circuit board 16. One end 40f of the noise-reducing sound hole 40e opens toward the noise microphone 20, and the other end 40g of the noise-reducing sound hole 40e opens toward the vehicle frame 701 side. More specifically, the other end 40g of the noise-reducing sound hole 40e is not blocked but is open toward the vehicle frame 701 side. Because the noise-reducing sound hole 40e is provided in this way, vibration noise 70b from the vehicle 70 is transmitted, for example, from the vehicle frame 701 through the noise-reducing sound hole 40e to the noise microphone 20.

[0114] Specifically, the noise-generating sound hole 40e is composed of a first substrate through-hole 40h including one end 40f of the noise-generating sound hole 40e, a second substrate through-hole 40i including the other end 40g of the noise-generating sound hole 40e, and a connecting hole 40j. The first substrate through-hole 40h penetrates the electrical substrate 16 at a position on one side 161 of the electrical substrate 16 facing the noise-generating microphone 20. The second substrate through-hole 40i penetrates the electrical substrate 16 at a position away from both the multiple speech microphones 12 and the noise-generating microphone 20. The connecting hole 40j penetrates the first laminated plate 41 and connects the first substrate through-hole 40h and the second substrate through-hole 40i. Furthermore, the side of the connecting hole 40j facing the passenger compartment 71 (i.e., the side opposite to the vehicle frame 701) is blocked by the second laminated plate 42.

[0115] With this configuration of the microphone support member 40, in this embodiment as in the first embodiment, the noise microphone 20 is positioned to be less likely to acquire the speaker's voice 73a and more likely to acquire the vibration sound 70b of the vehicle 70 compared to all the speech microphones 12.

[0116] (1) As described above, according to this embodiment, the microphone support member 40 includes an electrical circuit board 16 on which a speech microphone 12 and a noise microphone 20 are mounted. One end 40b of the sound hole 40a opens toward the speech microphone 12, and the other end 40c of the sound hole 40a opens toward the opposite side from the vehicle frame 701. On the other hand, one end 40f of the noise hole 40e opens toward the noise microphone 20, and the other end 40g of the noise hole 40e opens toward the vehicle frame 701.

[0117] Therefore, the noise microphone 20 and the speech microphones 12 can be arranged on a single electrical circuit board 16 such that the noise microphone 20 is less likely to acquire the speaker's voice 73a and is more likely to acquire the vibration sound 70b of the vehicle 70 compared to all the speech microphones 12. By having the noise microphone 20 and the speech microphones 12 on a common electrical circuit board 16 in this way, the signal transmission path between each microphone 12, 20 and the electrical circuit section 30 configured on the electrical circuit board 16 can be shortened.

[0118] In other words, if the output signal of the noise microphone 20 is an analog signal, it is possible to prevent a degradation in the quality of that signal. Also, if the output signal of the noise microphone 20 is a digital signal, it is possible to prevent a deterioration in EMC performance. "EMC" stands for "Electromagnetic Compatibility".

[0119] Furthermore, by mounting all microphones 12 and 20 on a common electrical circuit board 16, it is possible to reduce the amount of work required to install the voice acquisition device 10 on the vehicle 70.

[0120] (2) In addition, according to this embodiment, a noise microphone 20 is mounted on one surface 161 of the electrical circuit board 16 along with a plurality of speech microphones 12. The noise sound hole 40e of the microphone support member 40 is composed of a first substrate through hole 40h, a second substrate through hole 40i, and a connecting hole 40j. The first substrate through hole 40h penetrates the electrical circuit board 16 at a position on one surface 161 of the electrical circuit board 16 facing the noise microphone 20, and the second substrate through hole 40i penetrates the electrical circuit board 16 at a position away from all the microphones 12 and 20. The connecting hole 40j penetrates the first laminated plate 41 and connects the first substrate through hole 40h and the second substrate through hole 40i, and the side of the connecting hole 40j opposite to the vehicle frame 701 is blocked by the second laminated plate 42.

[0121] In this configuration, the microphones 12 and 20 are arranged such that the noise microphone 20 is less likely to acquire the speaker's voice 73a and more likely to acquire the vibration sound 70b of the vehicle 70 compared to all the speech microphones 12. Furthermore, while achieving this arrangement of microphones 12 and 20, all microphones 12 and 20 can be mounted on one side of the electrical circuit board 16. This makes it possible to reduce the mounting cost when mounting each microphone 12 and 20 on the electrical circuit board 16 compared to, for example, when multiple microphones 12 and 20 are mounted on one side 161 and the other side 162 of the electrical circuit board 16.

[0122] Except as described above, this embodiment is the same as the first embodiment. In this embodiment, the effects obtained from the configuration common to the first embodiment can be obtained in the same way as in the first embodiment.

[0123] Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with the fourth embodiment described above. In the modification combining the fourth embodiment and this embodiment, for example, the vibration-damping material 36 (see Figure 9) is sandwiched between the OHC 708 and the vehicle frame 701, and the OHC 708 is fixed to the vehicle frame 701.

[0124] (Other embodiments) (1) In each of the embodiments described above, the speech microphone 12 and the noise microphone 20 shown in Figure 2 etc. are both omnidirectional microphones, but this is just one example. For example, the speech microphone 12 may be a directional microphone, and the noise microphone 20 may also be a directional microphone.

[0125] For example, in the fifth embodiment, the speech microphone 12 shown in Figures 10 and 12 may have a directivity that is most sensitive when directed toward one end 40b of the sound hole 40a. And in the fifth embodiment, the noise microphone 20 may have a directivity that is most sensitive when directed toward one end 40f of the noise sound hole 40e.

[0126] (2) In each of the embodiments described above, eight speech microphones 12 are provided as shown in Figures 2 and 4, but any number is acceptable and there is no limit to the number of speech microphones 12. Furthermore, if there is no need to reduce directional noise, one speech microphone 12 may suffice.

[0127] (3) In each of the embodiments described above, the voice acquisition device 10 is equipped with an electrical circuit section 30, as shown in Figure 3, but this is just one example. For example, the voice acquisition device 10 may not be equipped with an electrical circuit section 30, and an electronic control device equivalent to the electrical circuit section 30 may be provided separately from the voice acquisition device 10.

[0128] (4) In each of the embodiments described above, the speech microphone 12 is mounted on the OHC 708, for example, as shown in Figure 2, but this is just one example. As long as the speaker's voice 73a is properly input to the speech microphone 12, the location of the speech microphone 12 may be other than the OHC 708, such as the instrument panel, headliner, center console, center cluster, or roof panel.

[0129] (5) The present invention is not limited to the embodiments described above and can be implemented in various modified forms. Furthermore, the embodiments described above are not unrelated to each other and can be combined as appropriate, except in cases where the combination is clearly impossible.

[0130] Furthermore, it goes without saying that, in each of the above embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated to be particularly essential or unless they are clearly considered essential in principle. Also, in each of the above embodiments, when numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated to be particularly essential or unless it is clearly limited to a specific number in principle. Also, in each of the above embodiments, when the material, shape, positional relationship, etc. of the components are mentioned, the embodiment is not limited to those material, shape, positional relationship, etc. unless explicitly stated or unless it is clearly limited to a specific material, shape, positional relationship, etc. in principle.

[0131] (Features of the present invention) [Claim 1] A voice acquisition device (10) for a voice recognition system, A speech microphone (12) that acquires the voice (73a) of a speaker (72) inside the vehicle compartment (71), The system acquires vibration noise (70b) of a vehicle (70), and includes a noise microphone (20) which is positioned to be less likely to acquire the speaker's voice and more likely to acquire the vibration noise compared to the speech microphone, The aforementioned speaking microphone has a plurality of frame components (702, 702a) and is constructed by connecting the plurality of frame components to each other, and is positioned on the passenger compartment side with respect to the vehicle frame (701) surrounding the passenger compartment. The noise microphone is installed on the nearest frame component (702a), which is the frame component closest to the speech microphone among a plurality of frame components, or on a component (38, 40) fixed to the nearest frame component on the vehicle interior side, in the voice acquisition device. [Claim 2] The aforementioned microphone for speaking is mounted on a support (708) that is positioned on the passenger compartment side of the vehicle frame and fixed to the vehicle frame. The sound acquisition device according to claim 1, wherein the noise microphone is installed on the vehicle frame so as to be covered by the support. [Claim 3] The sound acquisition device according to claim 1 or 2, wherein the noise microphone is fixed to the vehicle frame via a vibration-damping material (36). [Claim 4] The vehicle frame is provided with sound-absorbing material (24) positioned on the passenger compartment side, The sound-absorbing material has an internal space (24a) on the inside of the sound-absorbing material with an opening on the vehicle frame side. The sound acquisition device according to any one of claims 1 to 3, wherein the noise microphone is arranged in the internal space and surrounded by the sound-absorbing material. [Claim 5] The sound acquisition device according to claim 4, wherein the inner wall surface (24b) facing the internal space of the sound-absorbing material and surrounding the internal space is formed so as not to include parallel surfaces that are parallel to each other across the internal space. [Claim 6] The sound-absorbing material is formed to surround the noise-absorbing microphone when viewed in a direction along the normal direction of the mounting surface (701c) of the vehicle frame on which the noise-absorbing microphone is installed. The sound acquisition device according to claim 4, wherein the sound-absorbing material has a shape in which the internal space of the sound-absorbing material opens to the side opposite to the vehicle frame side. [Claim 7] The aforementioned microphone for speaking is mounted on an electrical circuit board (16) which is positioned on the vehicle interior side at a distance from the nearest frame component and fixed to the nearest frame component, The electrical circuit board has one surface (161) that faces the frame-facing portion (701b), which is part of the nearest frame component, The sound acquisition device according to any one of claims 1 to 6, wherein the noise microphone is positioned away from the one surface of the electrical circuit board and between the one surface and the frame-facing portion, and is installed on the frame-facing portion. [Claim 8] The electrical circuit board (16) on which the speech microphone and the noise microphone are mounted is equipped with a microphone support member (40) which is positioned on the passenger compartment side of the vehicle frame and fixed to the vehicle frame. The microphone support member is provided with a sound hole (40a) for sound and a noise hole (40e). One end (40b) of the sound hole for sound is open toward the speech microphone, The other end (40c) of the sound hole opens toward the opposite side from the vehicle frame. One end (40f) of the noise-generating sound hole opens toward the noise-generating microphone, The other end (40g) of the noise-generating sound hole opens toward the vehicle frame side, as described in claim 1 or 2. [Claim 9] An electrical circuit board (16) on which the speech microphone and the noise microphone are mounted and which has one side (161) facing the vehicle frame and another side (162) opposite to the one side; a first laminate (41) laminated on the other side of the electrical circuit board; and a second laminate (42) laminated on the other side of the electrical circuit board with the first laminate sandwiched between them; and a microphone support member (40) which is positioned on the passenger compartment side of the vehicle frame and fixed to the vehicle frame. The microphone support member is provided with a sound hole (40a) for sound and a noise hole (40e). The aforementioned sound hole is formed as a through-hole that penetrates the microphone support member in the direction normal to the surface (Dsb), One end (40b) of the sound hole for sound is open toward the speech microphone, The other end (40c) of the sound hole opens toward the opposite side from the vehicle frame. The noise-generating sound hole is composed of a first substrate through-hole (40h) that penetrates the electrical substrate at a position on one surface facing the noise-generating microphone, a second substrate through-hole (40i) that penetrates the electrical substrate at a position away from the speech microphone and the noise-generating microphone, and a connecting hole (40j) that penetrates the first laminate and connects the first substrate through-hole and the second substrate through-hole. The audio acquisition device according to claim 1 or 2, wherein the connecting hole on the side opposite to the vehicle frame is blocked by the second laminated plate. [Claim 10] Multiple first noise reduction units (31) and It includes a second noise reduction unit (32), Multiple microphones are provided for speech, and primary speech (73) including the speaker's voice is acquired. The plurality of first noise reduction units are provided in correspondence to each of the plurality of speech microphones, and based on the primary speech signal (S1v) obtained from the speech microphone and the acquired noise signal (Sn) obtained by the noise microphone and indicating noise including the vibration sound, a secondary speech signal (S2v) is obtained in which the diffuse noise is reduced compared to the primary speech, thereby making the speaker's voice stand out. The speech acquisition device according to any one of claims 1 to 9, wherein the second noise reduction unit obtains a third-order speech signal (S3v) in which the speaker's voice is highlighted by reducing directional noise, which has a higher directionality than the diffuse noise, compared to the second-order speech, based on the respective second-order speech signals obtained by the plurality of first noise reduction units. [Explanation of symbols]

[0132] 10. Voice acquisition device 12. Speech microphone 20 Noise-reducing microphones 70 vehicles 70b Vibration sound 72 speakers 71 Cabin 73a Speaker's voice (speaker's voice) 701 Vehicle Frame 708 OHC (Support Body)

Claims

1. A voice acquisition device (10) for a voice recognition system, A speech microphone (12) that acquires primary sound (73) including the voice (73a) of a speaker (72) inside the vehicle compartment (71), This system acquires vibration noise (70b) from a vehicle (70), and includes a noise microphone (20) positioned to be less effective at acquiring the speaker's voice and more effective at acquiring vibration noise compared to the speech microphone, Multiple first noise reduction units (31) and It includes a second noise reduction unit (32), The aforementioned speaking microphone has a plurality of frame components (702, 702a) and is constructed by connecting the plurality of frame components to each other, and is positioned on the passenger compartment side with respect to the vehicle frame (701) surrounding the passenger compartment. The noise microphone is installed on the nearest frame component (702a), which is the frame component closest to the speech microphone among the plurality of frame components, or on a component (38, 40) fixed to the nearest frame component on the vehicle interior side. Multiple microphones for speaking are provided. The plurality of first noise reduction units are provided in correspondence to each of the plurality of speech microphones, and based on the primary speech signal (S1v) obtained from the speech microphone and the acquired noise signal (Sn) obtained by the noise microphone and indicating noise including the vibration sound, a secondary speech signal (S2v) is obtained in which the diffuse noise is reduced compared to the primary speech, thereby making the speaker's voice stand out. The second noise reduction unit obtains a third-order speech signal (S3v) representing a third-order speech signal in which the speaker's voice is highlighted by reducing directional noise, which has a higher directionality than the diffuse noise, compared to the second-order speech signal, based on the respective second-order speech signals obtained by the plurality of first noise reduction units, in order to obtain a third-order speech signal.

2. The aforementioned microphone for speaking is mounted on a support (708) that is positioned on the passenger compartment side of the vehicle frame and fixed to the vehicle frame. The sound acquisition device according to claim 1, wherein the noise microphone is installed on the vehicle frame so as to be covered by the support.

3. The sound acquisition device according to claim 1 or 2, wherein the noise microphone is fixed to the vehicle frame via a vibration-damping material (36).

4. The vehicle frame is provided with sound-absorbing material (24) positioned on the passenger compartment side, The sound-absorbing material has an internal space (24a) on the inside of the sound-absorbing material with an opening on the vehicle frame side. The sound acquisition device according to claim 1 or 2, wherein the noise microphone is arranged in the internal space and surrounded by the sound-absorbing material.

5. The sound acquisition device according to claim 4, wherein the inner wall surface (24b) facing the internal space of the sound-absorbing material and surrounding the internal space is formed so as not to include parallel surfaces that are parallel to each other across the internal space.

6. The sound-absorbing material is formed to surround the noise-absorbing microphone when viewed in a direction along the normal direction of the mounting surface (701c) of the vehicle frame on which the noise-absorbing microphone is installed. The sound acquisition device according to claim 4, wherein the sound-absorbing material has a shape in which the internal space of the sound-absorbing material opens to the side opposite to the vehicle frame side.

7. The aforementioned microphone for speaking is mounted on an electrical circuit board (16) which is positioned on the vehicle interior side at a distance from the nearest frame component and fixed to the nearest frame component, The electrical circuit board has one surface (161) that faces the frame-facing portion (701b), which is part of the nearest frame component, The noise microphone is positioned away from the one surface of the electrical circuit board and between the one surface and the frame-facing portion, and is installed on the frame-facing portion, as described in claim 1 or 2 of the sound acquisition device.

8. The electrical circuit board (16) on which the speech microphone and the noise microphone are mounted is equipped with a microphone support member (40) which is positioned on the passenger compartment side of the vehicle frame and fixed to the vehicle frame. The microphone support member is formed with a sound hole (40a) for sound and a sound hole (40e) for noise. One end (40b) of the sound hole for sound is open toward the microphone for speech, The other end (40c) of the sound hole opens toward the opposite side from the vehicle frame. One end (40f) of the noise-generating sound hole opens toward the noise-generating microphone, The other end (40g) of the noise-generating sound hole opens toward the vehicle frame, as described in claim 1 or 2.

9. An electrical circuit board (16) on which the speech microphone and the noise microphone are mounted and which has one side (161) facing the vehicle frame and another side (162) opposite to the one side; a first laminate (41) laminated on the other side of the electrical circuit board; and a second laminate (42) laminated on the other side of the electrical circuit board with the first laminate sandwiched between them, and a microphone support member (40) which is positioned on the passenger compartment side of the vehicle frame and fixed to the vehicle frame, The microphone support member is formed with a sound hole (40a) for sound and a sound hole (40e) for noise. The aforementioned sound hole is formed as a through-hole that penetrates the microphone support member in the direction normal to the surface (Dsb), One end (40b) of the sound hole for sound is open toward the microphone for speech, The other end (40c) of the sound hole opens toward the opposite side from the vehicle frame. The noise-generating sound hole is composed of a first substrate through-hole (40h) that penetrates the electrical substrate at a position on one surface facing the noise-generating microphone, a second substrate through-hole (40i) that penetrates the electrical substrate at a position away from the speech microphone and the noise-generating microphone, and a connecting hole (40j) that penetrates the first laminate and connects the first substrate through-hole and the second substrate through-hole. The audio acquisition device according to claim 1 or 2, wherein the connecting hole on the side opposite to the vehicle frame is blocked by the second laminated plate.

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