JP2021044606A - On-vehicle acoustic system and vehicle - Google Patents

Abstract

To provide a technique allowing for suppression of generation of acoustic feedback in a vehicle compartment.SOLUTION: An on-vehicle acoustic system 1 includes: a right speaker 21 arranged in a right half 100R of a vehicle compartment 100a and emitting first sound; a left speaker 22 arranged in a left half 100L of the vehicle compartment 100a and emitting second sound including at least a partial component of the first sound; a right microphone 11 arranged in the right half 100R of the vehicle compartment 100a; a left microphone 12 arranged in the left half 100L of the vehicle compartment 100a; and a signal processing section 3 outputting to the right speaker 21, a first component signal RA which is based on a difference between a sound collection signal MR of the right microphone 11 and a sound collection signal ML of the left microphone 12, and outputting a second component signal LA which is based on the difference to the left speaker 22.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to in-vehicle audio systems and vehicles.

Patent Document 1 describes an in-vehicle karaoke system. In this system, a microphone and a speaker are arranged in the passenger compartment.

Japanese Unexamined Patent Publication No. 2005-242057

When a microphone and a speaker are arranged in the vehicle interior as described in Patent Document 1, howling is likely to occur in the vehicle interior.
An object of the present disclosure is to provide a technique capable of suppressing the occurrence of howling in a passenger compartment.

The vehicle-mounted acoustic system according to one aspect of the present disclosure is arranged in the right half of the passenger compartment and emits the first sound, and is arranged in the left half of the passenger compartment and at least a part of the first sound. The left speaker that emits the second sound containing the component of, the right microphone arranged in the right half of the passenger compartment, the left microphone arranged in the left half of the passenger compartment, and the sound collection signal of the right microphone. A signal processing unit that outputs a first component signal based on the difference between the sound picked up signal of the left microphone and the sound pick-up signal of the left microphone to the right speaker and outputs a second component signal based on the difference to the left speaker.

It is a figure which shows an example of the vehicle-mounted acoustic system 1 which concerns on 1st Embodiment of this disclosure. It is a figure which shows the vehicle 100 which carries the in-vehicle sound system 1. It is a figure which shows the positional relationship between a microphone, a speaker, and a seat. It is a figure which shows the positional relationship between a microphone, a speaker, and a user. It is a figure which shows an example of a signal processing unit 3. It is a figure which shows an example of the operation of an in-vehicle sound system 1. It is a figure which shows the 2nd modification of this disclosure.

<A: First Embodiment>
<A1: In-vehicle sound system 1>
FIG. 1 is a diagram showing an example of an in-vehicle sound system 1 according to the first embodiment of the present disclosure. The in-vehicle sound system 1 is mounted on a vehicle 100 such as an automobile. In the passenger compartment 100a of the vehicle 100, seats 51 to 54 forming two rows of seats, a front right door 71, a front left door 72, a rear right door 73, and a rear left door 74 are arranged.

In the following, as shown in FIG. 1 or 2, it is assumed that the X-axis, the Y-axis, the Z-axis, the straight line C, the straight line CR, and the straight line CL are used.
The X-axis, Y-axis, and Z-axis are orthogonal to each other. One direction along the X axis when viewed from an arbitrary point is referred to as the X1 direction, and the direction opposite to the X1 direction is referred to as the X2 direction. One direction along the Y axis when viewed from an arbitrary point is referred to as the Y1 direction, and the direction opposite to the Y1 direction is referred to as the Y2 direction. One direction along the Z axis when viewed from an arbitrary point is referred to as the Z1 direction, and the direction opposite to the Z1 direction is referred to as the Z2 direction. The XY plane including the X-axis and the Y-axis corresponds to a horizontal plane.
The X-axis is an axis along the length direction of the passenger compartment 100a. The Y-axis is an axis along the width direction of the passenger compartment 100a. The Y-axis is also an axis along the width direction of each of the seats 51 to 54. The Z-axis is an axis along the height direction of the passenger compartment 100a.
The straight line C is a straight line extending in the length direction of the passenger compartment 100a through the center of the width of the passenger compartment 100a in a plan view from above the passenger compartment 100a. Hereinafter, the plan view from above the passenger compartment 100a is simply referred to as "plan view". The straight line CR is a straight line extending in the length direction of the passenger compartment 100a through the center of the width of the seat 51 in a plan view. The straight line CL is a straight line extending in the length direction of the passenger compartment 100a through the center of the width of the seat 52 in a plan view.

Seats 51 and 52 are first row seats arranged along the Y axis. The seat 51 is a driver's seat. Seat 52 is a passenger seat. The seat 52 may be the driver's seat, and the seat 51 may be the passenger seat. Seats 53 and 54 are second row seats arranged along the Y axis. Seats 51-54 face the X2 direction.

The in-vehicle sound system 1 includes a right microphone 11, a left microphone 12, a right speaker 21, a left speaker 22, and a signal processing unit 3.
The right microphone 11 and the left microphone 12 are arranged symmetrically in the vehicle interior 100a. Here, the left-right symmetry includes a case where it can be regarded as left-right symmetry if various errors such as a manufacturing error of the in-vehicle sound system 1 and a manufacturing error of the vehicle 100 are ignored. Further, the left-right symmetry has an effect that the voice of the user sitting in any of the seats 51 to 54 can be emitted from the right speaker 21 and the left speaker 22 while suppressing the occurrence of howling in the passenger compartment 100a as described later. The positional relationship between the right microphone 11 and the left microphone 12 is also included.

The right microphone 11, the right speaker 21, and the seats 51 and 53 are arranged in the right half 100R of the passenger compartment 100a. The right half 100R of the passenger compartment 100a is a portion of the passenger compartment 100a located on the right side of the passenger compartment 100a (Y2 direction from the XZ plane passing through the straight line C) with respect to the XZ plane passing through the straight line C. ..

The left microphone 12, the left speaker 22, and the seats 52 and 54 are arranged in the left half 100L of the passenger compartment 100a. The left half 100L of the passenger compartment 100a is a portion of the passenger compartment 100a located on the left side of the passenger compartment 100a (Y1 direction from the XZ plane passing through the straight line C) with respect to the XZ plane passing through the straight line C. ..

The right microphone 11 is arranged in a portion of the ceiling 100b of the passenger compartment 100a shown in FIG. 2 that belongs to the right half 100R of the passenger compartment 100a. As an example, the right microphone 11 is arranged in a portion of the ceiling 100b located on the straight line CR in the plan view shown in FIG. The right microphone 11 may be arranged at a position different from the portion of the ceiling 100b located on the straight line CR in the plan view as long as it is located in the right half 100R of the vehicle interior 100a.

The right microphone 11 is a microphone having directivity. For example, howling can be reduced by setting the directivity direction of the right microphone 11 to a direction in which none of the speakers exists. The right microphone 11 does not have to have directivity.

The right microphone 11 collects sound in the vehicle interior 100a. The right microphone 11 outputs a sound collection signal MR based on the sound collected. The sound collection signal MR is an analog signal. The sound collection signal MR may be a digital signal.

The left microphone 12 is arranged in a portion of the ceiling 100b belonging to the left half 100L of the vehicle interior 100a. As an example, the left microphone 12 is arranged on the portion of the ceiling 100b located on the straight line CL in a plan view. The left microphone 12 may be arranged at a position different from the portion of the ceiling 100b located on the straight line CL in a plan view as long as it is located in the left half 100L of the vehicle interior 100a.

The left microphone 12 is a microphone having directivity. For example, howling can be reduced by setting the directivity direction of the left microphone 12 to a direction in which none of the speakers exists. The left microphone 12 does not have to have directivity. The left microphone 12 collects sound in the vehicle interior 100a. The left microphone 12 outputs a sound collection signal ML based on the sound collected. The sound pick-up signal ML is an analog signal. The sound collection signal ML may be a digital signal.

The right speaker 21 is arranged on the front light door 71. The front light door 71 is an example of a right door. The right speaker 21 does not have to be arranged on the front light door 71 as long as it is located on the right half 100R of the vehicle interior 100a. The first component signal RA including the right channel signal of the stereo signal is input to the right speaker 21. The right speaker 21 emits a sound based on the first component signal RA. The sound based on the first component signal RA is an example of the first sound.

The left speaker 22 is arranged on the front left door 72. The front left door 72 is an example of a left door. The left speaker 22 does not have to be arranged on the front left door 72 as long as it is located on the left half 100L of the vehicle interior 100a. The second component signal LA including the left channel signal of the stereo signal is input to the left speaker 22. The left speaker 22 emits a sound based on the second component signal LA. The sound based on the second component signal LA is an example of the second sound. Here, the left channel signal includes at least a part of the components of the right channel signal. Therefore, the sound based on the second component signal LA includes at least a part of the components of the sound based on the first component signal RA.

Various devices necessary for driving the vehicle 100 and the like, for example, a steering wheel, an accelerator pedal, a speed display, and the like are arranged in the vehicle interior 100a. Therefore, there is a restriction on the installation position of the speaker and the microphone in the vehicle interior 100a as compared with the case where the speaker and the microphone are installed in the room in the building. Therefore, in the passenger compartment 100a, howling cannot be suppressed only by adjusting the installation positions of the speaker and the microphone.
The signal processing unit 3 controls the right speaker 21 and the left speaker 22 by using the sound collecting signal MR and the sound collecting signal ML, thereby suppressing the occurrence of howling in the vehicle interior 100a as described later.

<A2: Processing of signal processing unit 3>
FIG. 3 is a diagram showing the positional relationship between the right microphone 11, the left microphone 12, the right speaker 21, the left speaker 22, the seat 51, and the seat 52. Hereinafter, the distance from the right speaker 21 to the right microphone 11 is referred to as “R1”. The distance from the right speaker 21 to the left microphone 12 is referred to as "R2". The distance from the left speaker 22 to the left microphone 12 is referred to as "L1". The distance from the left speaker 22 to the right microphone 11 is referred to as "L2".

In the in-vehicle sound system 1, the relationship of R1 = L1 and the relationship of L2 = R2 are satisfied. Therefore, the right microphone 11 collects the sound output by the right speaker 21 at a position where the distance from the right speaker 21 is R1. The right microphone 11 collects the sound output by the left speaker 22 at a position where the distance from the left speaker 22 is L2. The left microphone 12 collects the sound output by the left speaker 22 at a position where the distance from the left speaker 22 is L1. The left microphone 12 collects the sound output by the right speaker 21 at a position where the distance from the right speaker 21 is R2.

The degree of attenuation in the sound output by a sound source such as a speaker increases as the distance from the sound source increases. The output sound of the right speaker 21 and the output sound of the left speaker 22 have a common sound component. Therefore, due to the relationship of R1 = L1, the sound pressure in the common sound component from the right speaker 21 picked up by the right microphone 11 is the sound pressure in the common sound component from the left speaker 22 picked up by the left microphone 12. Is equal to. Further, due to the relationship of L2 = R2, the sound pressure in the common sound component from the left speaker 22 picked up by the right microphone 11 is the sound pressure in the common sound component from the right speaker 21 picked up by the left microphone 12. Become equal.

Therefore, when the difference between the sound pick-up signal MR of the right microphone 11 and the sound pick-up signal ML of the left microphone 12 is taken, the sound components common to the output sound from the right speaker 21 and the output sound from the left speaker 22 are canceled out. To.

Therefore, in order to suppress the occurrence of howling, the signal processing unit 3 outputs the first component signal RA based on the difference signal D indicating the difference between the sound collection signal MR and the sound collection signal ML to the right speaker 21, and the difference. The second component signal LA based on the signal D is output to the left speaker 22. As described above, the first component signal RA includes the right channel signal, and the second component signal LA includes the left channel signal.

Next, the positional relationship between the right microphone 11, the left microphone 12, the seat 51, and the seat 52 will be described. Hereinafter, the distance from the center 51b to the right microphone 11 on the seat surface 51a of the seat 51 is referred to as "E1". The center of gravity of the seating surface 51a may be used as the center 51b. The distance from the center 51b to the left microphone 12 is referred to as "E2". The distance from the center 52b of the seat surface 52a of the seat 52 to the left microphone 12 is referred to as "F1". The center of gravity of the seating surface 52a may be used as the center 52b. The distance from the center 52b to the right microphone 11 is referred to as "F2".

In the in-vehicle sound system 1, the relationship of E1 <E2 and the relationship of F1 <F2 are satisfied. Therefore, the distance from the right microphone 11 to the seat 51 is different from the distance from the left microphone 12 to the seat 51. Further, the distance from the right microphone 11 to the seat 52 is different from the distance from the left microphone 12 to the seat 52.

The size and the way of sitting of the user U1 sitting on the seat 51 are various. However, since the relationship E1 <E2 is satisfied for the seat 51, it is assumed that the distance from the mouth position of the user U1 to the right microphone 11 is shorter than the distance from the mouth position of the user U1 to the left microphone 12. Will be done. Further, since the relation F1 <F2 is satisfied for the seat 52, the distance from the mouth position of the user U2 sitting on the seat 52 to the left microphone 12 is larger than the distance from the mouth position of the user U2 to the right microphone 11. Is expected to be shorter.

FIG. 4 is a diagram showing the positional relationship between the right microphone 11, the left microphone 12, the mouth of the user U1, and the mouth of the user U2. Hereinafter, as the position U1a of the mouth of the user U1, a position separated from the center 51b in the Z2 direction by 80 cm is used. As the position U2a of the mouth of the user U2, a position 80 cm away from the center 52b in the Z2 direction is used. The positions U1a and U2a can be changed as appropriate.
The right microphone 11 picks up the voice of the user U1 at a position where the distance from the position U1a is G1. The left microphone 12 picks up the voice of the user U1 at a position where the distance from the position U1a is G2. Here, the relationship G1 <G2 is satisfied.

As described above, the degree of attenuation in the sound output by the sound source increases as the distance from the sound source increases. Therefore, due to the relationship of G1 <G2, the sound pressure in the voice of the user U1 picked up by the right microphone 11 is higher than the sound pressure in the voice of the user U1 picked up by the left microphone 12. Therefore, in the difference signal D indicating the difference between the sound collecting signal MR and the sound collecting signal ML, the component indicating the voice of the user U1 remains.

The right microphone 11 picks up the voice of the user U2 at a position where the distance from the position U2a is H2. The left microphone 12 picks up the voice of the user U2 at a position where the distance from the position U2a is H1. Here, the relationship H1 <H2 is satisfied. Therefore, the sound pressure in the voice of the user U2 picked up by the left microphone 12 is higher than the sound pressure in the voice of the user U2 picked up by the right microphone 11. Therefore, in the difference signal D, the component indicating the voice of the user U2 remains.

Therefore, when the signal processing unit 3 outputs the first component signal RA to the right speaker 21 and the second component signal LA to the left speaker 22, the voice components of the users U1 and U2 are output to the right speaker 21 and the left speaker. It becomes possible to generate from 22.

<A3: An example of signal processing unit 3>
FIG. 5 is a diagram showing an example of the signal processing unit 3. The signal processing unit 3 includes a storage unit 31, a processing calculation unit 32, ADCs (Analog to Digital Converters) 33 and 34, adders 35 and 36, and DACs (Digital to Analog Converters) 37 and 38. ..

The storage unit 31 is a recording medium that can be read by the processing calculation unit 32. The storage unit 31 stores a program executed by the processing calculation unit 32 and various information.

The processing calculation unit 32 is a computer such as a CPU (Central Processing Unit). The processing calculation unit 32 realizes the difference calculation unit 321 and the effector 322 by reading and executing the program stored in the storage unit 31.

The ADC 33 AD (Analog to Digital) converts the sound collection signal MR of the analog signal into the sound collection signal MRD of the digital signal. When the sound collection signal MR is a digital signal, the ADC 33 is omitted. The ADC 34 AD-converts the sound collecting signal ML of the analog signal into the sound collecting signal MLD of the digital signal. When the sound collection signal ML is a digital signal, the ADC 34 is omitted.

The difference calculation unit 321 generates a difference signal D indicating the difference between the sound collection signal MRD and the sound collection signal MLD. The effector 322 generates the processing signal E by performing effect processing such as equalizing on the difference signal D. The effector 322 may be omitted. When the effector 322 is omitted, the difference signal D is used instead of the processing signal E.

The adder 35 generates the first component signal RD by adding the processing signal E to the right channel signal R. The first component signal RD is a signal based on the right channel signal R and the processing signal E. Since the processing signal E is based on the difference signal D, the first component signal RD is also a signal based on the right channel signal R and the difference signal D.

The adder 36 generates the second component signal LD by adding the processing signal E to the left channel signal L. The second component signal LD is a signal based on the left channel signal L and the processing signal E. Furthermore, the second component signal LD is a signal based on the left channel signal L and the difference signal D.

The DAC 37 DA (Digital to Analog) converts the first component signal RD of the digital signal into the first component signal RA of the analog signal. The DAC 37 outputs the first component signal RA to the right speaker 21.

The DAC 38 DA-converts the second component signal LD of the digital signal into the second component signal LA of the analog signal. The DAC 38 outputs the second component signal LA to the left speaker 22.

<A4: Example of operation>
FIG. 6 is a diagram showing an example of the operation of the vehicle-mounted acoustic system 1. Hereinafter, an example in which the user U1 sitting in the seat 51 performs karaoke by using the in-vehicle sound system 1 will be described. The user U2 sitting in the seat 52 may perform karaoke instead of the user U1, and the users U1 and U2 may perform karaoke. The in-vehicle sound system 1 is not limited to use in karaoke. For example, in a situation where music is emitted from each of the right speaker 21 and the left speaker 22 in a stereo system or a monaural system, a person's sound system 1 is used in the passenger compartment 100a. It is applicable in the aspect of detecting voice.

In a situation where each of the right microphone 11 and the left microphone 12 is in the off state, the right channel signal R of the karaoke accompaniment music is input to the adder 35 from a music playback device (not shown), and the left channel signal L of the karaoke accompaniment music. Is input to the adder 36 from a music playback device (not shown). Therefore, the sound based on the right channel signal R is emitted from the right speaker 21 (step S1), and the sound based on the left channel signal L is emitted from the left speaker 22 (step S2). Step S1 and step S2 are executed in parallel. The sound based on the right channel signal R is another example of the first sound. The sound based on the left channel signal L is another example of the second sound.

After that, each of the right microphone 11 and the left microphone 12 is turned on, and the user U1 starts singing a song. Therefore, the right microphone 11 collects the sound emitted from the right speaker 21, the sound emitted from the left speaker 22, and the song emitted by the user U1. The right microphone 11 generates a sound collection signal MR based on the sound collected (step S3). The left microphone 12 also collects the sound emitted from the right speaker 21, the sound emitted from the left speaker 22, and the song emitted by the user U1. The left microphone 12 generates a sound collection signal ML based on the sound collected (step S4). The order of steps S3 and S4 may be reversed. Step S3 and step S4 may be executed in parallel.

Subsequently, the ADC 33 generates the sound collection signal MRD of the digital signal by AD-converting the sound collection signal MR of the analog signal (step S5). Further, the ADC 34 generates a sound collecting signal MLD of the digital signal by AD-converting the sound collecting signal ML of the analog signal (step S6). The order of steps S5 and S6 may be reversed. Step S5 and step S6 may be executed in parallel.

Subsequently, the difference calculation unit 321 generates the difference signal D by using the sound collection signal MRD and the sound collection signal MLD (step S7). For example, the difference calculation unit 321 generates the difference signal D by subtracting the sound collection signal MLD from the sound collection signal MRD. The difference calculation unit 321 may generate the difference signal D by subtracting the sound collection signal MRD from the sound collection signal MLD.

In the difference signal D, the components common to the sound collecting signal MRD and the sound collecting signal MLD are canceled out. Therefore, the sound component that causes howling, specifically, the sound component emitted from the right speaker 21 and the sound component emitted from the left speaker 22 is reduced in the difference signal D. Will be done. In the difference signal D, the component indicating the singing voice of the user U1 remains.

Subsequently, the effector 322 generates a processing signal E by performing effect processing on the difference signal D (step S8). The adder 35 generates the first component signal RD by adding the processing signal E to the right channel signal R (step S9). The adder 36 generates the second component signal LD by adding the processing signal E to the left channel signal L (step S10). The order of steps S9 and S10 may be reversed. Step S9 and step S10 may be executed in parallel.

Subsequently, the DAC 37 generates the first component signal RA by DA-converting the first component signal RD. The DAC 37 outputs the first component signal RA to the right speaker 21 (step S11).

Further, the DAC 38 generates the second component signal LA by DA-converting the second component signal LD. The DAC 38 outputs the second component signal LA to the left speaker 22 (step S12). The order of steps S11 and S12 may be reversed. Step S11 and step S12 may be executed in parallel. The right speaker 21 emits a sound corresponding to the first component signal RA, and the left speaker 22 emits a sound corresponding to the second component signal LA.

<A5: S / N ratio in the difference signal D>
The S / N ratio in the difference signal D will be described.
The difference signal D includes a voice component which is a component indicating a sound such as the singing voice of the user U1 and a music component which is a component indicating a sound emitted from each of the right speaker 21 and the left speaker 22.
The signal component S in the difference signal D is an audio component included in the difference signal D. Hereinafter, the audio component included in the difference signal D will be referred to as a “first audio component”.
The noise component N in the difference signal D is a music component included in the difference signal D. Hereinafter, the music component included in the difference signal D is referred to as a "first music component".

The first music component includes a component based on the difference between the right channel signal and the left channel signal. The first music component may further include, for example, a sound component of 2 kHz or more among the sound components common to the output sound from the right speaker 21 and the output sound from the left speaker 22.
Here, the reason why the first music component includes a sound component of 2 kHz or more will be described.
Since the right half 100R of the passenger compartment 100a and the left half 100L of the passenger compartment 100a do not have the same shape depending on the presence or absence of the steering wheel, the sound propagation characteristics are different. Therefore, the sound components common to the output sound from the right speaker 21 and the output sound from the left speaker 22 are not completely canceled, and for example, a sound component of 2 kHz or more tends to remain. The sound component of 2 kHz or higher is a sound component that is not often used in daily conversation. Therefore, even if the sound component of 2 kHz or more remains, the influence on the sound component is small as compared with the configuration in which the sound component of less than 2 kHz remains.

As described above, the first music component includes a component based on the difference between the right channel signal and the left channel signal, and a sound component of 2 kHz or more. Therefore, the first music component does not become zero. Therefore, the first music component shows the music that the right microphone 11 picks up from the right speaker 21 and the left speaker 22, and the left microphone 12 shows the music that picks up the sound from the right speaker 21 and the left microphone 12. Temporarily set to 1/2 of the total of the components.
The music component picked up by the right microphone 11 from the right speaker 21 and the left speaker 22 is "M1", and the music component picked up by the left microphone 12 from the right speaker 21 and the left speaker 22 is "M2". In this case, the first music component can be expressed as (M1 + M2) × (1/2).

On the other hand, the first voice component is a component obtained by subtracting the sound picked up by the left microphone 12 from the user U1 from the sound picked up by the right microphone 11 from the user U1. Here, assuming that the component of the sound collected by the right microphone 11 from the user U1 is "V1" and the component of the sound collected by the left microphone 12 from the user U1 is "V2", V2 is V1 × (G1 /). It can be expressed as G2). Therefore, the first audio component can be expressed as V1-V2 = V1 (1- (G1 / G2)).
Here, when G1 = 10 cm and G2 = 80 cm,
The first audio component = (7/8) × V1. G1 is not limited to 10 cm, and G2 is not limited to 80 cm.

Therefore, the S / N ratio in the difference signal D is
1st audio component / 1st music component = (7/8) x V1 / ((M1 + M2) x (1/2))
= (7/4) × (V1 / M1 + M2)
Will be.

Next, as a comparative example of the S / N ratio in the difference signal D, the S / N ratio in the added signal generated by adding the sound collecting signal MRD and the sound collecting signal MLD will be described.
The addition signal includes a voice component which is a component indicating a voice such as the singing voice of the user U1 and a music component which is a component indicating a sound emitted from each of the right speaker 21 and the left speaker 22.
The signal component S in the addition signal is a voice component of the user U1 included in the addition signal. Hereinafter, the voice component of the user U1 included in the addition signal is referred to as a "second voice component".
The noise component N in the added signal is a music component from each of the right speaker 21 and the left speaker 22 included in the added signal. Hereinafter, the music component from each of the right speaker 21 and the left speaker 22 included in the addition signal will be referred to as a “second music component”.

The second music component can be expressed as M1 + M2.
The second audio component can be expressed as V1 + V2 = V1 (1+ (G1 / G2)).
Here, when G1 = 10 cm and G2 = 80 cm, as in the above-mentioned example of calculating the S / N ratio in the difference signal D,
The second audio component = (9/8) × V1.

Therefore, the S / N ratio in the added signal is
2nd audio component / 2nd music component = (9/8) x V1 / (M1 + M2)
= (9/8) × (V1 / M1 + M2)
Will be.

Therefore, the relationship between the S / N ratio in the difference signal D and the S / N ratio in the addition signal is
S / N ratio in the difference signal D: S / N ratio in the addition signal = (7/4): (9/8)
= 14: 9
Will be.
Therefore, by using the difference signal D instead of the addition signal, the ratio of the signal component (component indicating the voice of the user U1) S to the noise component (sound component emitted from the speaker) N can be increased. Therefore, the voice of the user U1 can be efficiently picked up.

<A6: Summary of the first embodiment>
In the difference signal D that affects each of the first component signal RA and the second component signal LA, the sound component that causes howling is reduced, and the voice component of the user U1 and the like remains. Therefore, it is possible to generate the voice components of the users U1 and U2 from the right speaker 21 and the left speaker 22 while suppressing the occurrence of howling.

<B: Modification example>
An embodiment of the modification in the above-exemplified embodiment will be illustrated below. Two or more embodiments arbitrarily selected from the following examples may be appropriately merged to the extent that they do not contradict each other.

<B1: First modification>
In the above-described embodiment, the relationship of R1 = L1 and R2 = L2 is established. However, the relationship between R1 and L1 is not limited to the relationship of R1 = L1, and the relationship between R2 and L2 is not limited to the relationship of R2 = L2. Specifically, the relationship between R1 and L1 and R2 are within the range in which the effect of "the voice components of the users U1 and U2 can be generated from the right speaker 21 and the left speaker 22 while suppressing the occurrence of howling" is produced. The relationship with L2 may be changed. For example, when R1 is in the range of ± 10% of L1 and R2 is in the range of ± 10% of L2, the above-mentioned effect occurs. Therefore, R1 may be in the range of ± 10% of L1 and R2 may be in the range of ± 10% of L2.

<B2: Second modification>
In the above embodiment, the right speaker 21 is arranged on the front right door 71, and the left speaker 22 is arranged on the front left door 72. However, as shown in FIG. 7, the right speaker 21 may be arranged in the right pillar 71a of the passenger compartment 100a, and the left speaker 22 may be arranged in the left pillar 72a of the passenger compartment 100a. The pillar may be any pillar as long as it is a pillar in the passenger compartment 100a.

<B3: Third modification>
In the above-described embodiment, one speaker called the right speaker 21 is located in the right half 100R of the passenger compartment 100a, and one speaker called the left speaker 22 is located in the left half 100L of the passenger compartment 100a. However, two or more speakers may be provided in the right half 100R and the left half 100L of the passenger compartment 100a, respectively. In this case, the signal processing unit 3 has, for example, the sound pick-up signals of the plurality of speakers located in the right half 100R of the vehicle interior 100a and the sound collection signals of the plurality of speakers located in the left half 100L of the vehicle compartment 100a. A difference signal indicating the difference may be generated.
In the above embodiment, the in-vehicle sound system 1 is used for the seats 51 and 52 in the first row, but the in-vehicle sound system 1 may be used for the seats 53 and 54 in the second row. An in-vehicle sound system 1 may be used for both of the eye seats, respectively. Further, when the vehicle 100 has seats in the third and subsequent rows, the in-vehicle sound system 1 may be used for the seats in the third and subsequent rows.

<B4: Fourth modified example>
In the above-described embodiment, the right speaker 21 emits a sound based on the right channel signal, and the left speaker 22 emits a sound based on the left channel signal. However, a monaural sound signal may be used instead of each of the right channel signal and the left channel signal.

<B5: Fifth modification>
Even if all or a part of the elements realized by the processing calculation unit 32 in the above-described embodiment reading and executing the program is realized by a circuit such as FPGA (field programmable gate array) or ASIC (Application Specific IC). Good.

<C: Aspect grasped from the above-mentioned form>
The following aspects are grasped from at least one of the above-mentioned forms.

<C1: First aspect>
The in-vehicle sound system according to the aspect (first aspect) of the present disclosure is arranged in the right half of the vehicle interior and emits the first sound, and is arranged in the left half of the vehicle interior and the first sound. A left speaker that emits a second sound containing at least a part of the components, a right microphone arranged in the right half of the passenger compartment, a left microphone arranged in the left half of the passenger compartment, and the right microphone. A signal processing unit that outputs a first component signal based on the difference between the sound pick-up signal of the left microphone and the sound pick-up signal of the left microphone to the right speaker, and outputs a second component signal based on the difference to the left speaker. Including.
According to this aspect, in the first component signal and the second component signal based on the difference between the sound pick-up signal of the right microphone and the sound pick-up signal of the left microphone, the output sound from the right speaker and the output sound from the left speaker Common sound components are reduced. Therefore, it is possible to suppress the occurrence of howling in the vehicle interior where there are many restrictions on the installation positions of the speaker and the microphone.

<C2: Second aspect>
In the example of the first aspect (second aspect), the distance from the right speaker to the right microphone is in the range of ± 10% of the distance from the left speaker to the left microphone, and the distance from the right speaker to the left microphone. The distance to is in the range of ± 10% of the distance from the left speaker to the right microphone. According to this aspect, it is possible to arrange the right speaker, the right microphone, the left speaker, and the left microphone so that the occurrence of howling in the vehicle interior can be suppressed.

<C3: Third aspect>
In the example of the first aspect or the second aspect (third aspect), a seat is provided in the passenger compartment, and the distance from the right microphone to the seat is the distance from the left microphone to the seat. different. According to this aspect, it is possible to emit the voice of the user sitting in the seat from the right speaker and the left speaker while suppressing the occurrence of howling in the passenger compartment.

<C4: Fourth aspect>
In the example of the first aspect (fourth aspect), the right microphone and the left microphone are arranged symmetrically in the passenger compartment. Each seat in the passenger compartment is generally located in either the right or left half of the passenger compartment. Therefore, when the right microphone and the left microphone are arranged symmetrically in the passenger compartment, the distance from the right microphone to the seat is likely to be different from the distance from the left microphone to the seat. Therefore, according to this aspect, it is possible to emit the voice of the user sitting in the seat from the right speaker and the left speaker while suppressing the occurrence of howling in the vehicle interior.

<C5: Fifth aspect>
In any of the first to fourth aspects (fifth aspect), the right microphone and the left microphone are arranged on the ceiling of the vehicle interior. According to this aspect, the right microphone and the left microphone are provided on the ceiling of the passenger compartment, so that the passenger compartment can be effectively utilized.

<C6: Sixth aspect>
In any of the first to fifth aspects (sixth aspect), the right speaker is arranged on the right door of the passenger compartment, and the left speaker is arranged on the left door of the passenger compartment. The right door and the left door are generally arranged symmetrically in the passenger compartment. Therefore, according to this aspect, the right speaker and the left speaker can be arranged symmetrically in the passenger compartment.

<C7: Seventh aspect>
In any of the first to fifth aspects (seventh aspect), the right speaker is arranged in the right pillar of the passenger compartment, and the left speaker is arranged in the left pillar of the passenger compartment. The right pillar and the left pillar are generally arranged symmetrically in the passenger compartment. Therefore, according to this aspect, the right speaker and the left speaker can be arranged symmetrically in the passenger compartment.

<C8: Eighth aspect>
In any of the first to seventh aspects (eighth aspect), the first sound is a sound based on the right channel signal of the stereo signal, and the second sound is the left channel signal of the stereo signal. It is a sound based on. According to this aspect, even if stereo music is emitted from the right speaker and the left speaker, the voice of the user sitting in the seat is emitted from the right speaker and the left speaker while suppressing the occurrence of howling in the passenger compartment. It is possible to do.

<C9: 9th aspect>
The vehicle according to the other aspect (9th aspect) of the present disclosure includes an in-vehicle sound system according to any one of the 1st to 8th aspects. According to this aspect, it is possible to suppress the occurrence of howling in a vehicle interior in which there are many restrictions on the installation positions of the speaker and the microphone.

11 ... right microphone, 12 ... left microphone, 21 ... right speaker, 22 ... left speaker, 3 ... signal processing unit, 31 ... storage unit, 32 ... processing calculation unit, 321 ... difference calculation unit, 322 ... effector, 33 , 34 ... ADC, 35, 36 ... adder, 37, 38 ... DAC.

Claims (9)

The right speaker, which is located in the right half of the passenger compartment and emits the first sound,
A left speaker arranged in the left half of the passenger compartment and emitting a second sound containing at least a part of the first sound.
The right microphone located in the right half of the passenger compartment and
The left microphone located in the left half of the passenger compartment and
A signal processing unit that outputs a first component signal based on the difference between the sound picked up signal of the right microphone and the sound picked up signal of the left microphone to the right speaker, and outputs a second component signal based on the difference to the left speaker. When,
In-vehicle audio system including. The distance from the right speaker to the right microphone is in the range of ± 10% of the distance from the left speaker to the left microphone.
The distance from the right speaker to the left microphone is in the range of ± 10% of the distance from the left speaker to the right microphone.
The in-vehicle acoustic system according to claim 1. Seats are provided in the passenger compartment,
The distance from the right microphone to the seat is different from the distance from the left microphone to the seat.
The vehicle-mounted acoustic system according to claim 1 or 2. The right microphone and the left microphone are arranged symmetrically in the passenger compartment.
The in-vehicle acoustic system according to claim 1. The right microphone and the left microphone are arranged on the ceiling of the passenger compartment.
The vehicle-mounted acoustic system according to any one of claims 1 to 4. The right speaker is located on the right door of the passenger compartment.
The left speaker is located on the left door of the passenger compartment.
The vehicle-mounted acoustic system according to any one of claims 1 to 5. The right speaker is arranged in the right pillar of the passenger compartment.
The left speaker is arranged in the left pillar of the passenger compartment.
The vehicle-mounted acoustic system according to any one of claims 1 to 5. The first sound is a sound based on the right channel signal of the stereo signal.
The second sound is a sound based on the left channel signal of the stereo signal.
The vehicle-mounted acoustic system according to any one of claims 1 to 7. A vehicle including the in-vehicle sound system according to any one of claims 1 to 8.

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