WO2017175304A1

WO2017175304A1 - Sound output system, sound output device, and control device

Info

Publication number: WO2017175304A1
Application number: PCT/JP2016/061114
Authority: WO
Inventors: 豊小谷; 木村　勝
Original assignee: 三菱電機株式会社
Priority date: 2016-04-05
Filing date: 2016-04-05
Publication date: 2017-10-12

Abstract

A control device (30): generates a sound signal (L') in which a left-channel sound signal (L) and a first signal for diffraction erasure to erase a first diffraction wave (W1) that is outputted from a second speaker (4) and that propagates to a right-hand seat are synthesized, and outputs the sound signal (L') to a first speaker (3); generates a sound signal (R') in which a right-channel sound signal (R) and a second signal for diffraction erasure to erase a second diffraction wave (W2) that is outputted from the first speaker (3) and that propagates to a left-hand seat are synthesized, and outputs the sound signal (R') to the second speaker (4); outputs the right-channel sound signal (R) to a third speaker (6); and outputs the left-channel sound signal (L) to a fourth speaker (7).

Description

Audio output system, audio output device and control device

The present invention relates to an audio output system compatible with stereo, and an audio output device and a control device for the audio output system.

Conventionally, in a vehicle audio output system, a system that realizes stereo by providing speakers on both sides of a vehicle interior and using the left speaker for the left channel and the right speaker for the right channel has become widespread. is doing. In this system, the left channel speaker and the right channel speaker are arranged asymmetrically with respect to the driver's seat, and the sound field with respect to the driver's seat is asymmetrical. In addition, this system has a problem that the left channel speaker and the right channel speaker are arranged asymmetrically with respect to the passenger seat, and the sound field with respect to the passenger seat becomes asymmetrical.

In addition to speakers on both sides of the passenger compartment, an audio output system has been developed that has a monaural center speaker in the center of the dashboard. In this system, the center speaker outputs monaural sound by combining the left channel and the right channel, and the sound field for each of the driver's seat and front passenger seat is the same as in the system without the center speaker. There was a problem of becoming asymmetric.

In response to this problem, an audio output system in which a center speaker is composed of two speakers has been proposed (see, for example, Patent Document 1 and Patent Document 2). The systems of Patent Document 1 and Patent Document 2 improve the left-right symmetry of the sound field with respect to the driver's seat by using a speaker directed to the driver's seat among the center speakers in a right-hand drive four-wheeled vehicle. is doing. Moreover, the system of patent document 1 and patent document 2 is improving the left-right symmetry of the sound field with respect to a passenger seat by using for the right channel the speaker pointed to the passenger seat among center speakers.

Japanese Unexamined Patent Publication No. 64-29200 Japanese Utility Model Publication No. 6-27355

The center speakers of Patent Document 1 and Patent Document 2 are a speaker in which a first speaker directed to a driver's seat and a second speaker directed to a passenger seat are arranged adjacent to each other. In the center speaker, due to diffraction between adjacent speakers, a part of the sound wave of the left channel output from the first speaker propagates around the passenger seat from the right and is output from the second speaker. A part of the sound wave in the right channel propagates around the driver's seat from the left. The sound output systems of Patent Document 1 and Patent Document 2 have a problem that the symmetry of the sound field cannot be sufficiently improved due to the influence of such a diffracted wave. As a result, the position of the sound image with respect to the driver's seat shifts to the left and right from the front of the driver's seat, and the position of the sound image with respect to the passenger's seat shifts to the left and right from the front of the passenger's seat. .

The present invention has been made to solve the above problems, and in a sound output system that realizes stereo using a center speaker, the left / right symmetry of the sound field with respect to each of the seats arranged side by side The purpose is to improve.

The audio output system of the present invention includes a first speaker disposed between the right seat and the left seat so as to face the right seat, a second speaker disposed adjacent to the first speaker and facing the left seat, An audio output device including a third speaker disposed on the right side of the right seat and facing the right seat; and a fourth speaker disposed on the left side of the left seat and facing the left seat; and a left channel And a first diffraction canceling signal for canceling the first diffracted wave output from the second speaker and propagating to the right seat is generated and output to the first speaker, and the right channel. And a second diffraction canceling signal for canceling the second diffracted wave output from the first speaker and propagating to the left seat is generated and output to the second speaker, and the right channel Audio signal is output to the 3rd speaker and left channel In which a control device for outputting an audio signal to the fourth speaker.

According to the present invention, in a sound output system that realizes stereo using a center speaker, it is possible to improve the left-right symmetry of the sound field for each of the seats arranged side by side.

It is explanatory drawing which shows the state which provided the audio | voice output apparatus which concerns on Embodiment 1 of this invention in the vehicle. It is a front view of the center speaker which concerns on Embodiment 1 of this invention. It is a functional block diagram which shows the principal part of the audio | voice output system which concerns on Embodiment 1 of this invention. It is a circuit diagram which shows an example of the circuit structure of the diffraction cancellation circuit which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the state which provided the other audio | voice output apparatus which concerns on Embodiment 1 of this invention in the vehicle. It is a functional block diagram which shows the principal part of the other audio | voice output system which concerns on Embodiment 1 of this invention.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is an explanatory diagram illustrating a state in which a sound output device according to Embodiment 1 of the present invention is provided in a vehicle. FIG. 2 is a front view of the center speaker according to Embodiment 1 of the present invention. FIG. 3 is a functional block diagram showing the main part of the audio output system according to Embodiment 1 of the present invention. The audio output system 100 according to the first embodiment will be described with reference to FIGS.

First, the audio output device 10 will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, a center speaker 2, a third speaker 6, and a fourth speaker 7 are provided in a vehicle 1 that is a right-hand drive four-wheeled vehicle.

The center speaker 2 is provided on the dashboard of the vehicle 1. The center speaker 2 is between a right seat (hereinafter referred to as “driver's seat”) of the front seats of the vehicle 1 and a left seat (hereinafter referred to as “passenger seat”) of the front seats of the vehicle 1. Is arranged. The center speaker 2 includes a first speaker 3 that faces the driver's seat, a second speaker 4 that faces the passenger seat, and a housing 5 that houses the first speaker 3 and the second speaker 4.

The first speaker 3 is constituted by, for example, a so-called “cone type” or “dome type” speaker. The diameter of the first speaker 3 is set to a value at which sound waves in a frequency band of approximately 200 Hz or higher (hereinafter referred to as “medium / high range”) of a human audible frequency band can be output.

The second speaker 4 is disposed adjacent to the first speaker 3 and is configured by the same speaker as the first speaker 3. The aperture of the second speaker 4 is set to a value that can output mid-high frequency sound waves.

The casing 5 has a substantially isosceles triangular prism shape. A first opening 51 is formed in a surface corresponding to one of the equal sides, and the first speaker 3 is exposed from the first opening 51. A second opening 52 is formed in the surface corresponding to the other equilateral side, and the second speaker 4 is exposed from the second opening 52. A convex portion 53 is formed between the first opening 51 and the second opening 52 by a ridge line portion between a surface portion corresponding to one equilateral side and a surface portion corresponding to the other equilateral side.

The third speaker 6 is provided at the right end of the dashboard of the vehicle 1 so as to face the driver's seat. The third speaker 6 is configured by the same speaker as the first speaker 3. The aperture of the third speaker 6 is set to a value that can output mid-high range sound waves.

The fourth speaker 7 is provided at the left end of the dashboard of the vehicle 1 so as to face the passenger seat. The fourth speaker 7 is configured by the same speaker as the first speaker 3. The aperture of the fourth speaker 7 is set to a value that can output mid-high frequency sound waves.

Here, both the sound axis A1 of the first speaker 3 and the sound axis A3 of the third speaker 6 are directed to the driver's seat of the vehicle 1. Specifically, the sound axes A1 and A3 are directed to positions corresponding to the head of the driver P1 when the driver P1 is seated on the driver's seat, such as a headrest of the driver's seat. Similarly, the sound axis A2 of the second speaker 4 and the sound axis A4 of the fourth speaker 7 are both directed to the passenger seat of the vehicle 1. Specifically, the sound axes A2 and A4 are directed to positions corresponding to the head of the passenger P2 when the passenger P2 is seated on the passenger seat, such as a headrest of the passenger seat.

That is, in the center speaker 2, the first speaker 3 and the second speaker 4 are provided in different directions, and an opening angle θ is formed between the sound axes A1 and A2.

Further, the first speaker 3 and the third speaker 6 are arranged symmetrically with respect to the driver's seat. Thereby, in a state where the driver P1 is seated on the driver's seat, the distance from the first speaker 3 to the head of the driver P1 is equal to the distance from the third speaker 6 to the head of the driver P1. Similarly, the second speaker 4 and the fourth speaker 7 are arranged symmetrically with respect to the passenger seat. Thus, in a state where the passenger P2 is seated in the passenger seat, the distance from the second speaker 4 to the head of the passenger P2 is equal to the distance from the fourth speaker 7 to the head of the passenger P2.

The center speaker 2, the third speaker 6, and the fourth speaker 7 constitute an audio output device 10.

Next, the sound source 20 and the control device 30 will be described with reference to FIGS. 1 and 3.
The left channel sound source 20a outputs a left channel audio signal L. The right channel sound source 20b outputs a right channel audio signal R. A sound source 20 is constituted by the left channel sound source 20a and the right channel sound source 20b.

The sound source 20 is an in-vehicle information device such as a car navigation device, a car audio device, or a display audio device mounted on the vehicle 1. Alternatively, the sound source 20 is a portable information terminal such as a smartphone, a tablet computer, or a PND (Portable Navigation Device) brought into the vehicle 1. That is, the audio signals L and R are audio signals corresponding to music, audio of moving images, audio that guides the travel route of the vehicle 1, and the like.

The diffraction cancellation circuit 31 accepts input of audio signals L and R. The diffraction canceling circuit 31 cancels the left channel audio signal L and a sound wave (hereinafter referred to as “first diffracted wave”) W1 that is output from the second speaker 4 and propagates to the driver's seat by diffraction. The voice signal L ′ synthesized with “the first diffraction cancellation signal” is generated. The first diffraction erasure signal is, for example, an audio signal corresponding to the reverse phase of the first diffracted wave W1.

The diffraction canceling circuit 31 also cancels the right-channel audio signal R and the sound wave (hereinafter referred to as “second diffracted wave”) W2 that is output from the first speaker 3 and propagates to the passenger seat by diffraction. (Hereinafter referred to as “second diffraction cancellation signal”) is generated. The second diffraction erasure signal is, for example, an audio signal corresponding to the opposite phase of the second diffracted wave W2. The diffraction cancellation circuit 31 outputs the generated audio signals L ′ and R ′.

The audio signal L ′ output from the diffraction cancellation circuit 31 is sequentially output through the first gain adjustment circuit 32 a and the first delay adjustment circuit 33 a and output to the first speaker 3. The audio signal R ′ output from the diffraction cancellation circuit 31 is sequentially output through the second gain adjustment circuit 32 b and the second delay adjustment circuit 33 b and output to the second speaker 4.

In addition, the audio signal R input from the right channel sound source 20b sequentially passes through the third gain adjustment circuit 32c and the third delay adjustment circuit 33c, and is output to the third speaker 6. The audio signal L input from the left channel sound source 20a sequentially passes through the fourth gain adjustment circuit 32d and the fourth delay adjustment circuit 33d and is output to the fourth speaker 7.

The gain adjustment circuit 32 is constituted by the first gain adjustment circuit 32a, the second gain adjustment circuit 32b, the third gain adjustment circuit 32c, and the fourth gain adjustment circuit 32d. The first delay adjustment circuit 33a, the second delay adjustment circuit 33b, the third delay adjustment circuit 33c, and the fourth delay adjustment circuit 33d constitute a delay adjustment circuit 33.

The gain adjusting circuit 32 adjusts the gain of the audio signals L, R, L ', and R'. Specifically, for example, the gain adjustment circuit 32 is configured so that the volume of the left channel and the volume of the right channel that the driver P1 listens in the state where the driver P1 is seated in the driver's seat are equal to each other. This adjusts the gain of L ′ and the gains of the audio signals R and R ′. The gain adjustment circuit 32 also adjusts the gains of the audio signals L and L ′ so that the volume of the left channel and the volume of the right channel that the passenger P2 listens to are equal when the passenger P2 is seated in the passenger seat. The gain of the audio signals R and R ′ is adjusted.

The delay adjustment circuit 33 adjusts the delay of the audio signals L, R, L ′, and R ′. Specifically, for example, the delay adjustment circuit 33 compensates for the delay of the audio signals L ′ and R ′ with respect to the audio signals L and R generated by the diffraction cancellation circuit 31 and outputs each speaker of the audio output device 10. The timing of audio is aligned.

The control device 30 is configured by the diffraction cancellation circuit 31, the gain adjustment circuit 32, and the delay adjustment circuit 33. The control device 30 is realized by a processor such as a microcontroller or a DSP (Digital Signal Processor), for example. The audio output system 100 is configured by the audio output device 10 and the control device 30.

The diffraction elimination circuit 31 may have any circuit configuration as long as it outputs the audio signals L ′ and R ′ in response to the input of the audio signals L and R. Hereinafter, two specific examples of the diffraction cancellation circuit 31 will be described.

In the first example, a manufacturer of the audio output system 100 or the vehicle 1 (hereinafter, simply referred to as “manufacturer”) performs the following operation after the prototype of the vehicle 1 is completed and before the shipment of the vehicle 1 is started. Do work.

First, the manufacturer attaches a microphone to the headrest of the driver's seat or the head of the person sitting on the driver's seat, and inputs a test audio signal to the second speaker 4. The manufacturer receives the sound wave output from the second speaker 4 and measures characteristics such as the amplitude, frequency, or phase of the sound wave input to the microphone, and the inverse transfer function of the transfer function (hereinafter referred to as “first inverse”) representing the characteristic. "Transfer function"). The first inverse transfer function is a transfer function corresponding to the reverse phase of the first diffracted wave W1.

In addition, the manufacturer attaches a microphone to the headrest of the passenger seat or the head of the person seated on the passenger seat, and inputs a test audio signal to the first speaker 3. The manufacturer receives the sound wave output from the first speaker 3 and measures characteristics such as the amplitude, frequency, or phase of the sound wave input to the microphone, and the inverse transfer function of the transfer function (hereinafter referred to as “second inverse”) representing the characteristic. "Transfer function"). The second inverse transfer function is a transfer function corresponding to the opposite phase of the second diffracted wave W2.

Next, the manufacturer stores the calculated first and second inverse transfer functions in a memory (not shown) of the diffraction cancellation circuit 31. This memory is composed of a nonvolatile semiconductor memory such as a ROM (Read Only Memory), for example.

When the audio signals L and R are input, the diffraction cancellation circuit 31 converts the right channel audio signal R into a phase opposite to that of the first diffracted wave W1 by a convolution operation with the first inverse transfer function stored in advance in the memory. A corresponding audio signal, that is, a first diffraction cancellation signal is generated. The diffraction cancellation circuit 31 generates an audio signal L ′ by performing a convolution operation between the audio signal L of the left channel and the first diffraction cancellation signal.

Further, when the audio signals L and R are input, the diffraction cancellation circuit 31 performs an inverse operation of the second diffracted wave W2 by a convolution operation between the audio signal L of the left channel and the second inverse transfer function stored in advance in the memory. An audio signal corresponding to the phase, that is, a second diffraction cancellation signal is generated. The diffraction cancellation circuit 31 generates an audio signal R ′ by convolution of the right channel audio signal R and the second diffraction cancellation signal.

In the second example, the circuit configuration of the diffraction cancellation circuit 31 is simplified by using a mutual transfer function between the first speaker 3 and the second speaker 4.

That is, the center speaker 2 is disposed in the center of the dashboard, the shape of the center speaker 2 is bilaterally symmetric, the vehicle compartment shape of the vehicle 1 is bilaterally symmetric, and When the arrangement of the objects is symmetrical, the sound wave transfer function from the first speaker 3 to the second speaker 4 and the sound wave transfer function from the second speaker 4 to the first speaker 3 are substantially the same function, It can be regarded as a mutual transfer function between the first speaker 3 and the second speaker 4. In this case, the audio signals L ′ and R ′ for the audio signals L and R can be calculated using the mutual transfer function between the first speaker 3 and the second speaker 4. The manufacturer measures the attenuation characteristics of the first speaker 3 and the second speaker 4, calculates a mutual transfer function between the first speaker 3 and the second speaker 4, and stores it in a memory (not shown) of the diffraction cancellation circuit 31 in advance. Remember.

An example of the circuit configuration in this case is shown in FIG. The difference signal generation circuit 41 generates a difference signal between the audio signals L and R. The sum signal generation circuit 42 generates a sum signal of the audio signals L and R. The diffraction erasure signal generation circuit 43 uses the difference signal generated by the difference signal generation circuit 41 and the mutual transfer function stored in advance in the memory to erase the first diffracted wave W1 and the second diffracted wave W2. Signal (hereinafter referred to as “diffraction cancellation signal”). The phase inversion circuit 44 inverts the phase of the diffraction cancellation signal generated by the diffraction cancellation signal generation circuit 43.

The first adder 45 adds the sum signal generated by the sum signal generation circuit 42 and the diffraction cancellation signal after the phase inversion by the phase inversion circuit 44. The signal after the addition by the first adder 45 is a signal corresponding to a signal obtained by combining the left channel audio signal L and the first diffraction cancellation signal, that is, the audio signal L ′.

The second adder 46 adds the sum signal generated by the sum signal generation circuit 42 and the diffraction cancellation signal generated by the diffraction cancellation signal generation circuit 43. The signal after the addition by the second adder 46 becomes a signal corresponding to a signal obtained by synthesizing the right-channel audio signal R and the second diffraction cancellation signal, that is, the audio signal R ′.

Next, the operation and effect of the audio output system 100 will be described.
First, the sound source 20 outputs the audio signals L and R to the control device 30.

Next, the diffraction cancellation circuit 31 generates audio signals L ′ and R ′. The gain adjustment circuit 32 adjusts the gain of the audio signals L, R, L ′, and R ′. The delay adjustment circuit 33 adjusts the delay of the audio signals L, R, L ′, R ′.

Next, the control device 30 outputs the audio signal L ′ after the delay adjustment by the first delay adjustment circuit 33 a to the first speaker 3. The control device 30 outputs the audio signal R ′ after the delay adjustment by the second delay adjustment circuit 33 b to the second speaker 4. The control device 30 outputs the audio signal R after the delay adjustment by the third delay adjustment circuit 33 c to the third speaker 6. The control device 30 outputs the audio signal L after the delay adjustment by the fourth delay adjustment circuit 33 d to the fourth speaker 7.

Next, the first speaker 3 outputs a component corresponding to the mid-high range of the audio signal L ′ as a sound wave. The second speaker 4 outputs a component corresponding to the mid-high range of the audio signal R ′ as a sound wave. The third speaker 6 outputs a component corresponding to the mid-high range of the audio signal R as a sound wave. The fourth speaker 7 outputs a component corresponding to the mid-high range of the audio signal L as a sound wave. Thereby, the stereo with respect to each of a driver's seat and a passenger seat is realized.

At this time, the first speaker 3 and the third speaker 6 are arranged symmetrically with respect to the driver's seat, the first speaker 3 outputs the left channel sound toward the driver's seat, and the third speaker 6 Outputs the right channel sound toward the driver's seat. Thereby, the left-right symmetry of the stereo sound field with respect to the driver's seat can be improved as compared with a conventional system having no center speaker or a conventional system having a monaural center speaker.

Similarly, the second speaker 4 and the fourth speaker 7 are arranged symmetrically with respect to the passenger seat, the fourth speaker 7 outputs the left channel sound toward the passenger seat, and the second speaker 4 Output the right channel sound toward the passenger seat. Thereby, the left-right symmetry of the stereo sound field with respect to the passenger seat can be improved as compared with a conventional system having no center speaker or a conventional system having a monaural center speaker.

Further, the center speaker 2 has the sound axis A1 of the first speaker 3 directed toward the driver's seat and the sound axis A2 of the second speaker 4 directed toward the passenger seat, and the opening angle between the sound axes A1 and A2 θ is formed. Further, the housing 5 has a ridge-shaped convex portion 53 between the first opening 51 and the second opening 52. Thereby, the 1st diffracted wave W1 and the 2nd diffracted wave W2 can be reduced. As a result, the influence of the diffracted wave can be reduced, and the left-right symmetry of the stereo sound field with respect to each of the driver seat and the passenger seat can be further improved.

Further, the control device 30 outputs an audio signal L ′ obtained by synthesizing the audio signal L of the left channel and the first diffraction cancellation signal to the first speaker 3, and also outputs the audio signal R of the right channel and the second diffraction cancellation. The audio signal R ′ synthesized with the signal for use is output to the second speaker 4. Thereby, the 1st diffracted wave W1 and the 2nd diffracted wave W2 can be canceled. As a result, it is possible to further reduce the influence of the diffracted wave and further improve the left-right symmetry of the stereo sound field with respect to each of the driver seat and the passenger seat.

Further, the first speaker 3, the second speaker 4, the third speaker 6 and the fourth speaker 7 are constituted by speakers capable of outputting middle and high range sound waves. In general, sound waves in a frequency band of about 200 Hz to several kilohertz (hereinafter referred to as “middle range”) are important for localization of a stereo sound image. The audio output system 100 can improve the localization accuracy of the sound image with respect to each of the driver seat and the passenger seat by improving the left-right symmetry of the stereo sound field in the middle range. In other words, it is possible to prevent the position of the sound image with respect to the driver's seat from shifting to the left and right from the front of the driver's seat and the position of the sound image with respect to the passenger's seat from shifting to the left and right from the front of the passenger's seat.

In general, sound waves in a frequency band of 1 kHz or higher (hereinafter referred to as “high range”) in the human audible frequency band have high directivity, and the sound volume greatly decreases as the sound axis deviates from the sound axis. On the other hand, in the audio output system 100, the sound axis A1 of the first speaker 3 that outputs the middle and high range of the left channel is directed to the driver's seat, and the sound axis of the third speaker 6 that outputs the middle and high range of the right channel. A3 is directed to the driver's seat. As a result, the driver P1 seated in the driver's seat can surely listen to the high frequencies of both the left and right channels. Similarly, in the audio output system 100, the sound axis A4 of the fourth speaker 7 that outputs the mid-high range of the left channel is directed to the passenger seat, and the sound axis A2 of the second speaker 4 that outputs the mid-high range of the right channel. Is directed to the passenger seat. As a result, the passenger P2 seated in the passenger seat can reliably listen to the high frequencies of both the left and right channels.

The first speaker 3, the second speaker 4, the third speaker 6, and the fourth speaker 7 emit sound waves of only one of the mid-high frequency ranges, for example, the mid-frequency range or the high-frequency range. It may be output. In general, the diameter of a speaker becomes smaller as the lowest output frequency becomes higher. For this reason, for example, by using a speaker that outputs only a high frequency, the diameters of the first speaker 3, the second speaker 4, the third speaker 6, and the fourth speaker 7 are reduced, and the audio output device 10 is reduced in size. be able to.

The center speaker 2 is disposed in front of the front seat of the vehicle 1, to the left of the right seat of the front seat, and to the right of the left seat of the front seat. What is necessary is just what was provided, and what was provided in members other than a dashboard may be sufficient.

Further, the third speaker 6 may be disposed in front of the front seat of the vehicle 1 and to the right of the right seat among the front seats, and is provided on a member other than the dashboard. It may be. The 4th speaker 7 should just be arrange | positioned ahead of the front seat of the vehicle 1, and the left of the left seat of the front seats, and was provided in members other than a dashboard. It may be. For example, the third speaker 6 and the fourth speaker 7 may be provided on a window column between the windshield and the side glass of the vehicle 1, so-called “A pillar”.

Further, the number of speakers included in the audio output device 10 is not limited to four. Hereinafter, an audio output system 100 in which the audio output device 10 is provided with six speakers will be described with reference to FIGS. As shown in FIG. 5, a fifth speaker 8 is provided on the right door of the vehicle 1, and a sixth speaker 9 is provided on the left door. The fifth speaker 8 and the sixth speaker 9 are constituted by speakers that can output sound waves in a frequency band (hereinafter referred to as “low range”) of approximately less than 200 hertz among human audible frequency bands.

As shown in FIG. 6, the gain adjustment circuit 32 has a fifth gain adjustment circuit 32e and a sixth gain adjustment circuit 32f. The delay adjustment circuit 33 includes a fifth delay adjustment circuit 33e and a sixth delay adjustment circuit 33f. The audio signal R input from the right channel sound source 20b sequentially passes through the fifth gain adjustment circuit 32e and the fifth delay adjustment circuit 33e and is output to the fifth speaker 8. The audio signal L input from the left channel sound source 20a is sequentially output through the sixth gain adjustment circuit 32f and the sixth delay adjustment circuit 33f and output to the sixth speaker 9.

The fifth speaker 8 outputs a component corresponding to a low frequency in the audio signal R as a sound wave. The sixth speaker 9 outputs a component corresponding to the low frequency of the audio signal L as a sound wave. With the system configuration shown in FIGS. 5 and 6, the audio output system 100 can output low-frequency sound while improving the left-right symmetry of the stereo sound field in the mid-high range.

Further, a system configuration in which an amplifier (not shown) or the like is provided between the sound source 20 and the control device 30 or between the control device 30 and the audio output device 10 and the audio output system 100 includes this amplifier or the like may be employed.

In general, in an in-vehicle audio output system, a speaker according to the distance between the speaker and the head of the occupant, that is, the position of the occupant's head relative to the longitudinal direction of the vehicle, such as the seat position or the reclining angle. It is known that the transfer function of sound waves from the vehicle to the head of the passenger is greatly different. Therefore, the control device 30 has a function of calculating the positions of the driver's and passenger's heads with respect to the front-rear direction of the vehicle 1 using a camera or the like provided in the vehicle 1 and capable of photographing the interior of the vehicle. May be. In this case, for example, in the first example, the manufacturer calculates the first inverse transfer function and the second inverse transfer function for each position of the driver's and passenger's heads, and stores them in the memory of the diffraction cancellation circuit 31 in advance. Remember. The diffraction cancellation circuit 31 generates a first diffraction cancellation signal and a second diffraction cancellation signal using the first inverse transfer function and the second inverse transfer function corresponding to the position of the head calculated using a camera or the like. To do. On the other hand, in the second example, the manufacturer calculates an expression or parameter used for generating the diffraction cancellation signal for each position of the driver's and passenger's heads, and stores it in the memory of the diffraction cancellation circuit 31 in advance. Let me. The diffraction cancellation signal generation circuit 43 generates a diffraction cancellation signal using an expression or a parameter corresponding to the position of the head calculated using a camera or the like.

Also, the audio output system 100 is not limited to being mounted on a vehicle. The audio output system 100 can be used for any audio output system as long as the center speaker 2, the third speaker 6, and the fourth speaker 7 are installed on the right seat and the left seat arranged in parallel to each other. It is possible to improve the left-right symmetry of the stereo sound field for each of the right seat and the left seat. However, in general, the vehicle 1 has a limited space in the passenger compartment, and a portion where a speaker can be installed is also limited. For this reason, the audio output system 100 that improves the left-right symmetry of the stereo sound field by combining the center speaker 2 and the third speaker 6 and the fourth speaker 7 provided on both sides of the vehicle 1 is particularly useful.

As described above, the audio output system 100 according to Embodiment 1 includes the first speaker 3 disposed between the right seat and the left seat so as to face the right seat, and the left speaker adjacent to the first speaker 3. The second speaker 4 disposed in the right direction, the third speaker 6 disposed on the right side of the right seat and facing the right seat, and the second speaker disposed on the left side of the left seat and facing the left seat. An audio output device 10 having four speakers 7, a left channel audio signal L, and a first diffraction cancellation signal for canceling the first diffraction wave W1 output from the second speaker 4 and propagating to the right seat. A synthesized signal (audio signal L ′) is generated and output to the first speaker 3, and the right channel audio signal R and the second diffracted wave W2 output from the first speaker 3 and propagating to the left seat are eliminated. Signal (sound signal R) synthesized with the second diffraction cancellation signal for ) Is output to the second loudspeaker 4 to generate and output a sound signal R for the right channel to the third speaker 6, and a control unit 30 for outputting an audio signal L of the left channel to the fourth speaker 7. The control device 30 generates the audio signals L ′ and R ′ and outputs them to the center speaker 2, so that the first diffracted wave W 1 and the second diffracted wave W 2 are canceled, and the stereo sound fields for the right seat and the left seat respectively. The left-right symmetry can be improved. As a result, the sound quality in both the right seat and the left seat can be improved.

The first speaker 3 and the second speaker 4 are housed in a housing 5, and the housing 5 includes a first opening 51 where the first speaker 3 is exposed and a second opening where the second speaker 4 is exposed. A convex portion 53 is provided between the first projection 52 and the second projection 52. The first diffracted wave W <b> 1 and the second diffracted wave W <b> 2 are reduced by the ridge-line-shaped convex portion 53, and the left / right symmetry of the stereo sound field with respect to the right seat and the left seat can be further improved.

Also, the sound axis A1 of the first speaker 3 is directed to the right seat, and the sound axis of the second speaker 4 is directed to the left seat. The first diffracted wave W1 and the second diffracted wave W2 are reduced by the opening angle θ between the sound axes A1 and A2, and the left-right symmetry of the stereo sound field with respect to the right seat and the left seat can be further improved.

Further, the first speaker 3, the second speaker 4, the third speaker 6 and the fourth speaker 7 are constituted by speakers capable of outputting middle and high range sound waves. Thereby, the left-right symmetry of the stereo sound field in the middle region is improved, and the localization accuracy of the sound image with respect to each of the driver seat and the passenger seat can be improved. In addition, the sound axes A1 and A3 of the first speaker 3 and the third speaker 6 are directed to the driver seat, and the sound axes A2 and A4 of the second speaker 4 and the fourth speaker 7 are directed to the passenger seat, so that the driver Both passengers P1 and passenger P2 can reliably listen to the high-frequency sound of the left and right channels.

In the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted within the scope of the invention.

The present invention can be used in an audio output system that realizes stereo using a center speaker. In particular, it is suitable for an in-vehicle audio output system.

1 vehicle, 2 center speaker, 3rd speaker, 4th speaker, 5 housing, 6 3rd speaker, 7th 4th speaker, 8th 5th speaker, 9th 6th speaker, 10 audio output device, 20 sound source, 20a Left channel sound source, 20b right channel sound source, 30 control device, 31 diffraction cancellation circuit, 32 gain adjustment circuit, 32a first gain adjustment circuit, 32b second gain adjustment circuit, 32c third gain adjustment circuit, 32d fourth gain adjustment circuit , 32e fifth gain adjustment circuit, 32f sixth gain adjustment circuit, 33 delay adjustment circuit, 33a first delay adjustment circuit, 33b second delay adjustment circuit, 33c third delay adjustment circuit, 33d fourth delay adjustment circuit, 33e fourth 5 delay adjustment circuit, 33f 6th delay adjustment circuit, 41 difference signal generation circuit, 42 sum signal generation circuit, 4 Diffraction erasing signal generating circuit, 44 a phase inversion circuit 45 first adder 46 second adder, 51 a first opening, 52 second opening, 53 protrusion, 100 audio output system.

Claims

A first speaker disposed between the right seat and the left seat and facing the right seat; a second speaker disposed adjacent to the first speaker and facing the left seat; and more than the right seat An audio output device having a third speaker disposed on the right side and facing the right seat; and a fourth speaker disposed on the left side of the left seat and facing the left seat;
A signal is generated by combining a left channel audio signal and a first diffraction cancellation signal for canceling the first diffraction wave output from the second speaker and propagating to the right seat to the first speaker. Generating a signal in which a right channel audio signal and a second diffraction cancellation signal for canceling the second diffraction wave output from the first speaker and propagating to the left seat are combined to generate the first channel A control device for outputting to two speakers, outputting the right channel audio signal to the third speaker, and outputting the left channel audio signal to the fourth speaker;
A voice output system comprising:
The first diffraction cancellation signal is an audio signal corresponding to a reverse phase of the first diffracted wave,
The audio output system according to claim 1, wherein the second diffraction cancellation signal is an audio signal corresponding to an opposite phase of the second diffracted wave.
The first speaker and the second speaker are housed in a housing,
The audio output system according to claim 1, wherein the casing has a convex portion between a first opening from which the first speaker is exposed and a second opening from which the second speaker is exposed.
The sound output system according to claim 1, wherein the sound axis of the first speaker is directed to the right seat, and the sound axis of the second speaker is directed to the left seat.
The sound output system according to claim 1, wherein the sound axis of the third speaker is directed to the right seat and the sound axis of the fourth speaker is directed to the left seat.
The first speaker and the third speaker are arranged symmetrically with respect to the right seat, and the second speaker and the fourth speaker are arranged symmetrically with respect to the left seat. The audio output system according to claim 1.
The audio output system according to claim 1, wherein the first speaker, the second speaker, the third speaker, and the fourth speaker are configured by a speaker capable of outputting middle and high frequency sound waves.
The right seat and the left seat are front seats of the vehicle, the first speaker and the second speaker are provided on a dashboard of the vehicle, and the third speaker and the fourth speaker are of the vehicle. The audio output system according to claim 1, wherein the audio output system is provided on a dashboard or a pillar.
A first speaker disposed between the right seat and the left seat and facing the right seat; a second speaker disposed adjacent to the first speaker and facing the left seat; and more than the right seat A control device for an audio output device, comprising: a third speaker arranged on the right side and facing the right seat; and a fourth speaker arranged on the left side of the left seat and facing the left seat. Because
A signal is generated by combining a left channel audio signal and a first diffraction cancellation signal for canceling the first diffraction wave output from the second speaker and propagating to the right seat to the first speaker. Generating a signal in which a right channel audio signal and a second diffraction cancellation signal for canceling the second diffraction wave output from the first speaker and propagating to the left seat are combined to generate the first channel 2. The control apparatus according to claim 1, wherein the control unit outputs to the second speaker, outputs the audio signal of the right channel to the third speaker, and outputs the audio signal of the left channel to the fourth speaker.
The first diffraction cancellation signal is an audio signal corresponding to a reverse phase of the first diffracted wave,
The control device according to claim 9, wherein the second diffraction erasing signal is an audio signal corresponding to a reverse phase of the second diffracted wave.
A first speaker disposed opposite the right seat between the right seat and the left seat;
A second speaker disposed adjacent to the first speaker and facing the left seat;
A housing that houses the first speaker and the second speaker;
The audio output device according to claim 1, wherein the housing has a convex portion between a first opening from which the first speaker is exposed and a second opening from which the second speaker is exposed.
12. The audio output device according to claim 11, wherein the sound axis of the first speaker is directed to the right seat and the sound axis of the second speaker is directed to the left seat.
A third speaker disposed on the right side of the right seat and facing the right seat;
A fourth speaker disposed on the left side of the left seat and facing the left seat;
The audio output device according to claim 11, further comprising:
14. The audio output device according to claim 13, wherein the sound axis of the third speaker is directed to the right seat, and the sound axis of the fourth speaker is directed to the left seat.
The first speaker and the third speaker are arranged symmetrically with respect to the right seat, and the second speaker and the fourth speaker are arranged symmetrically with respect to the left seat. The audio output device according to claim 13.
14. The audio output device according to claim 13, wherein the first speaker, the second speaker, the third speaker, and the fourth speaker are configured by a speaker capable of outputting middle and high frequency sound waves.