JP2020137041A - Phase control device, acoustic device, and phase control method - Google Patents

Abstract

To suppress a sound quality deterioration and a sound pressure deterioration, due to interference of sounds output from each speaker while improving an inclination of a sound image localization.SOLUTION: A phase control device is structured so that an impulse response is measured in each speaker, a predetermined phase control is performed for a frequency spectrum signal in each impulse response, a first amplitude characteristic is obtained by being synthesized with the other frequency spectrum signal, a second amplitude characteristic is obtained by being synthesized with the other frequency spectrum signal without performing the phase control, a speaker that satisfies a prescribed condition is detected from a plurality of speakers on the basis of the first and second amplitude characteristics, and second phase adjustment data for adjusting the phase of a signal of a sound output to each speaker in each frequency spectrum so as to reduce attenuation due to an interference of the sound between the speakers in each frequency spectrum at a plurality of hearing positions on the basis of first phase adjustment data for adjusting the phase of the signal of the sound output to the detected speaker in each frequency spectrum.SELECTED DRAWING: Figure 3

Description

The present invention relates to a phase control device, an acoustic device, and a phase control method.

Generally, speakers are installed at a plurality of positions in the vehicle interior. For example, the right front speaker of the right door part (driver's side door part) and the left front speaker of the left door part (passenger's side door part) are installed at symmetrical positions across the center line of the passenger compartment space. There is. However, these speakers are not in symmetrical positions when the listener's listening position (driver's seat, passenger's seat, rear seat, etc.) is considered as a reference.

For example, when the listener sits in the driver's seat, the distance between the right front speaker and the listener is not equal to the distance between the left front speaker and the listener. In the case of a right-hand drive vehicle, the distance of the former is shorter than the distance of the latter. Therefore, when the sound is output from the speakers of both doors at the same time, the sound output from the right front speaker reaches the ears of the listener sitting in the driver's seat, and then the sound output from the left front speaker reaches. Is common. The difference in the distance between the listener's listening position and each of the plurality of speakers (the difference in the time it takes for the reproduced sound emitted from each speaker to reach) causes a bias in sound image localization due to the Haas effect.

As an example of a technique for improving the bias of sound image localization, time alignment is known in which a delay time is set for each speaker channel so that the sound output from each speaker reaches the listener (listening position) at the same time. A specific configuration of the device for performing time alignment is described in, for example, Patent Document 1.

In the device described in Patent Document 1, since the delay time is set for each speaker channel, the sounds sequentially output from each speaker are sequentially picked up at a predetermined listening position, and the impulses for each speaker are sequentially picked up from each picked up sound. Measure the response. In Patent Document 1, a low-pass filter is applied to the impulse response to remove high-frequency noise to detect the rising portion of the impulse response with high accuracy, thereby improving the calculation accuracy of the delay time to be set for each speaker channel. ing.

Japanese Unexamined Patent Publication No. 2005-341534

In a special listening environment such as in a vehicle interior, the sounds output from each speaker are likely to interfere with each other. Therefore, it is difficult to avoid the deterioration of sound quality and the decrease of sound pressure due to the occurrence of dip in the frequency domain due to such interference only by the conventional technique for localizing the sound image such as time alignment.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the bias of sound image localization and to suppress deterioration of sound quality and sound pressure due to interference between sounds output from each speaker. It is to provide a phase control device, a sound device, and a phase control method capable of the above.

The phase control device according to an embodiment of the present invention measures the impulse response of a signal of each sound output from each of a plurality of speakers and picked up at a predetermined listening position at a timing that does not interfere with time. The unit, the Fourier conversion unit that obtains the frequency spectrum signal of the impulse response for each speaker by Fourier-converting the impulse response of the sound signal from each measured speaker, and each frequency spectrum signal obtained by the Fourier conversion unit. On the other hand, the first amplitude characteristic is obtained by performing a predetermined phase control and synthesizing with another frequency spectrum signal in which the predetermined phase control is not performed, and synthesizing with another frequency spectrum signal without performing the phase control. The amplitude characteristic calculation unit that obtains the second amplitude characteristic, and the speaker that satisfies a predetermined condition is detected from a plurality of speakers based on the first amplitude characteristic and the second amplitude characteristic obtained for each speaker. Based on the first phase adjustment data for adjusting the phase of the sound signal output to the detection unit and the detected speaker for each frequency spectrum, a plurality of listening positions including a predetermined listening position Second phase adjustment data for adjusting the phase of the sound signal output to each of the plurality of speakers for each frequency spectrum so that the weakening due to sound interference between the speakers is reduced in each frequency spectrum. It is provided with a generation unit that generates

According to the phase control device configured in this way, it is possible to improve the bias of the sound image localization and suppress the deterioration of sound quality and the decrease of sound pressure due to the interference between the sounds output from each speaker.

The detection unit calculates the level difference between the first amplitude characteristic and the second amplitude characteristic for each speaker, compares the values corresponding to the calculated level difference for each speaker, and determines a predetermined value based on the comparison result. A speaker that satisfies the conditions may be detected. More specifically, the detection unit calculates the level difference for each frequency spectrum, accumulates the calculated level difference for each frequency spectrum, compares the cumulative value of the level difference obtained for each speaker, and obtains the cumulative value. The largest speaker may be detected as a speaker satisfying a predetermined condition.

By generating the second phase adjustment data based on the first phase adjustment data for adjusting the phase of the sound signal output to the speaker detected in this manner for each frequency spectrum, the sound can be further adjusted. In addition to improving the bias of sound image localization, it is possible to suppress deterioration of sound quality and sound pressure due to interference between sounds output from each speaker.

The amplitude characteristic calculation unit may be configured to perform the following processes (1) to (5) for each frequency spectrum signal obtained by the Fourier transform unit.
(1) The phase of the frequency spectrum signal to be processed is changed, and each time the phase is changed, the frequency spectrum signal to be processed and another frequency spectrum signal are combined.
(2) Based on the result of synthesis, the phase adjustment amount of the sound signal from the speaker to be processed is obtained for each frequency spectrum.
(3) Complexly multiply the obtained phase adjustment amount for each frequency spectrum and the frequency spectrum signal to be processed by complex numbers.
(4) The first amplitude characteristic is obtained by synthesizing the complex-multiplied frequency spectrum signal and another frequency spectrum signal.
(5) A second amplitude characteristic is obtained by synthesizing the frequency spectrum signal to be processed and another frequency spectrum signal without changing the phase.

By using the first amplitude characteristic and the second amplitude characteristic obtained in this way, an effect (an effect of increasing the level by reducing the interference of sound weakening between speakers at the listening position) can be obtained. More suitable speakers can be detected.

In the first phase adjustment data, for example, the phase of the sound output from the speaker detected by the detection unit and the phase of the sound output from another speaker are in phase or out of phase in each frequency spectrum at the listening position. This is data for adjusting the phase of the sound output to the detected speaker for each frequency spectrum.

By using such the first phase adjustment data, it is more preferable to improve the bias of the sound image localization and to suppress the deterioration of the sound quality and the sound pressure due to the interference between the sounds output from each speaker. It is possible to generate the phase adjustment data of.

Based on the first phase adjustment data, the generation unit calculates the phase adjustment amount given to the sound signal output to each of the plurality of speakers for each frequency spectrum, and the calculated phase adjustment for each frequency spectrum. The quantity may be obtained as the second phase adjustment data. In this case, the generation unit may calculate the phase adjustment amount so that the difference in the phase adjustment amount given to the sound signals output to each of the plurality of speakers is within 180 degrees in each frequency spectrum.

This makes it even more under a given listening environment (for example, at both a listening position that is asymmetric with respect to the position of the pair of speakers and another listening position that is also asymmetric with respect to the position of the pair of speakers). , It is possible to reduce the interference of sound between speakers due to the opposite phase, improve the localization, and suppress the deterioration of sound quality and the decrease of sound pressure due to the occurrence of dips.

The acoustic device according to the embodiment of the present invention is a device having the above-mentioned phase control device and outputting a sound signal input from a sound source to a plurality of speakers, and uses the second phase adjustment data. , The configuration may include an adjusting unit that adjusts the phase of the sound signal input from the sound source and output to each of the plurality of speakers for each frequency spectrum.

According to the acoustic device configured in this way, it is possible to improve the bias of sound image localization at the listening position and output a sound signal to each speaker in which sound quality deterioration and sound pressure decrease due to interference between sounds are suppressed at the listening position. Is possible.

The phase control method executed by a computer according to an embodiment of the present invention is a signal of each sound output from each of a plurality of speakers and picked up at a predetermined listening position at a timing that does not interfere with time. A measurement step for measuring the impulse response, a Fourier transform step for obtaining the frequency spectrum signal of the impulse response for each speaker by Fourier transforming the impulse response of the sound signal from each measured speaker, and a Fourier transform step for obtaining the frequency spectrum signal of the impulse response. A predetermined phase control is performed on each of the obtained frequency spectrum signals, and the first amplitude characteristic is obtained by synthesizing with another frequency spectrum signal in which the predetermined phase control is not performed, and the other without performing the phase control. A predetermined amplitude characteristic calculation step for obtaining a second amplitude characteristic by synthesizing with the frequency spectrum signal of the above, and a predetermined number from a plurality of speakers based on the first amplitude characteristic and the second amplitude characteristic obtained for each speaker. A predetermined listening position is included based on the detection step of detecting a speaker satisfying the condition and the first phase adjustment data for adjusting the phase of the sound signal output to the detected speaker for each frequency spectrum. To adjust the phase of the sound signal output to each of the plurality of speakers for each frequency spectrum so that weakening due to sound interference between the plurality of speakers is reduced in each frequency spectrum at a plurality of listening positions. It includes a generation step of generating a second phase adjustment data.

According to such a phase control method, it is possible to improve the bias of the sound image localization and suppress the deterioration of sound quality and the decrease of sound pressure due to the interference between the sounds output from each speaker.

According to one embodiment of the present invention, a phase control device, an acoustic device, and a phase control capable of improving the bias of sound image localization and suppressing sound quality deterioration and sound pressure drop due to interference between sounds output from each speaker. The method is provided.

It is a figure which shows typically the vehicle which installed the acoustic system which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the acoustic system which concerns on one Embodiment of this invention. It is a figure which shows the flowchart of the data setting process for phase adjustment executed in the acoustic system which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the calculation part which the acoustic apparatus provided in the acoustic system which concerns on one Embodiment of this invention has. FIG. 5A is a diagram showing an impulse response between the left front speaker and the listening position (driver's seat), and FIG. 5B is a diagram showing an impulse response between the right front speaker and the listening position. FIG. 6A is a diagram showing the amplitude characteristics for each frequency spectrum obtained by Fourier transforming the impulse response between the left front speaker and the listening position, and FIG. 6B is a diagram showing the right front speaker and the listening position. It is a figure which shows the amplitude characteristic for each frequency spectrum obtained by Fourier transforming the impulse response between. FIG. 7A is a diagram showing the phase characteristics for each frequency spectrum obtained by Fourier transforming the impulse response between the left front speaker and the listening position, and FIG. 7B is a diagram showing the right front speaker and the listening position. It is a figure which shows the phase characteristic for every frequency spectrum obtained by Fourier transforming the impulse response between. FIG. 8 (a) is a diagram showing a synthesis result when a frequency spectrum signal obtained by Fourier transforming the impulse response between the left front speaker and the listening position is used as a processing target, and FIG. 8 (b) is a diagram. It is a figure which shows the synthesis result when the frequency spectrum signal obtained by Fourier transforming the impulse response between a right front speaker and a listening position is processed. FIG. 9A shows Fourier transform of the impulse response between the left front speaker and the listening position when the phase of the sound from the right front speaker and the phase of the sound from the left front speaker are in phase at the listening position. 9 (b) is a diagram showing the phase adjustment amount of the frequency spectrum signal obtained by the above, and FIG. 9 (b) shows the case where the phase of the sound from the right front speaker and the phase of the sound from the left front speaker are in phase at the listening position. It is a figure which shows the phase adjustment amount of the frequency spectrum signal obtained by Fourier transforming the impulse response between a right front speaker and a listening position. FIG. 10A is a diagram showing the first amplitude characteristic and the second amplitude characteristic obtained for the frequency spectrum signal obtained by Fourier transforming the impulse response between the left front speaker and the listening position. FIG. 10 (b) is a diagram showing the first amplitude characteristic and the second amplitude characteristic obtained for the frequency spectrum signal obtained by Fourier transforming the impulse response between the right front speaker and the listening position. 11 (a) is a diagram showing the level difference between the first amplitude characteristic and the second amplitude characteristic shown in FIG. 10 (a) for each frequency spectrum, and FIG. 11 (b) is a diagram showing FIG. 10 (b). It is a figure which shows the level difference between the 1st amplitude characteristic and the 2nd amplitude characteristic shown in b) for each frequency spectrum. A frequency spectrum signal obtained by Fourier transforming the impulse response between the right front speaker and the listening position when the phase of the sound from the right front speaker and the phase of the sound from the left front speaker are out of phase at the listening position. It is a figure which shows the phase adjustment amount (the first phase adjustment data) for every frequency spectrum of. It is a figure which shows the phase adjustment amount for every frequency spectrum determined in step S23 of FIG. It is a figure which shows the phase adjustment amount (the first phase adjustment data for a reference speaker) after the smoothing processing by the smoothing processing unit which the calculation unit which concerns on one Embodiment of this invention has. It is a figure which shows the phase adjustment amount (the second phase adjustment data for another speaker) obtained by the phase inversion part which has the acoustic apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the phase adjustment part which the acoustic apparatus which concerns on one Embodiment of this invention has. FIG. 17A is a diagram showing the time characteristics of the audio signal picked up by the microphone installed in the driver's seat in the example without control, and FIG. 17B is a diagram showing the time characteristic of the audio signal picked up by the microphone installed in the driver's seat. It is a figure which shows the time characteristic of the audio signal picked up by the installed microphone. FIG. 18A is a diagram showing the time characteristics of the audio signal picked up by the microphone installed in the passenger seat in the example without control, and FIG. 18B is a diagram showing the time characteristics of the audio signal picked up by the microphone installed in the passenger seat. It is a figure which shows the time characteristic of the audio signal picked up by the installed microphone. It is a figure which shows the frequency characteristic of the audio signal of an uncontrolled example and the frequency characteristic of an audio signal of a phase adjustment example picked up by a microphone installed in a driver's seat. It is a figure which shows the frequency characteristic of the audio signal of an uncontrolled example and the frequency characteristic of an audio signal of a phase adjustment example picked up by a microphone installed in a passenger seat. In another embodiment, it is a diagram showing the frequency characteristic of the audio signal of the uncontrolled example and the frequency characteristic of the audio signal of the phase adjustment example picked up by the microphone installed in the driver's seat. In another embodiment, it is a diagram showing the frequency characteristic of the audio signal of the uncontrolled example and the frequency characteristic of the audio signal of the phase adjustment example picked up by the microphone installed in the passenger seat.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, an acoustic system will be described as an example of an embodiment of the present invention.

FIG. 1 is a diagram schematically showing a vehicle A in which the acoustic system 1 according to the embodiment of the present invention is installed. FIG. 2 is a block diagram showing the configuration of the acoustic system 1.

As shown in FIGS. 1 and 2, the acoustic system 1 includes an acoustic device 10, a speaker SP _FR , an SP _FL, and a microphone MIC.

The sound device 10 is for improving the bias of sound image localization that tends to occur in the listening environment of the vehicle interior and suppressing deterioration of sound quality and sound pressure due to interference between sounds output from each speaker installed in the vehicle A. It is equipped with a phase adjustment data generation function (in other words, a phase control device) that generates phase adjustment data.

The various processes in the acoustic device 10 are executed by the cooperation of the software and the hardware provided in the acoustic device 10. At least the OS (Operating System) part of the software provided in the sound device 10 is provided as an embedded system, but the other parts, for example, the software module for executing the phase adjustment data generation process , May be provided as an application that can be distributed on a network or held on a recording medium such as a memory card. That is, the phase adjustment data generation function according to the present embodiment may be a function incorporated in the acoustic device 10 in advance, or a function that can be added to the acoustic device 10 via a network or a recording medium.

As shown in FIG. 1, the speaker SP _FR is a right front speaker embedded in the right door portion (driver's seat side door portion), and the speaker SP _FL is embedded in the left door portion (passenger's seat side door portion). It is the left front speaker. Yet another speaker (for example, a rear speaker) may be installed in the vehicle A (that is, three or more speakers are installed).

The sound device 10 includes a control unit 100, a display unit 102, an operation unit 104, a measurement signal generation unit 106, a recording medium reproduction unit 108, a phase adjustment unit 110, an amplification unit 112, a signal recording unit 114, and a calculation unit 116.

FIG. 3 is a diagram showing a flowchart of a phase adjustment data setting process executed in the acoustic system 1. Various processes in the acoustic system 1, including the phase adjustment data setting process shown in this flowchart, are executed under the control of the control unit 100. When the control unit 100 receives a predetermined touch operation on the display unit 102 or a predetermined operation on the operation unit 104, the control unit 100 starts executing the phase adjustment data setting process shown in this flowchart.

When the execution of the phase adjustment data setting process shown in FIG. 3 is started, the measurement signal generation unit 106 generates a predetermined measurement signal (step S11). The generated measurement signal is, for example, an M-sequence code (Maximal length sequence). The length of this measurement signal shall be at least twice the code length. The measurement signal may be another type of signal such as a TSP signal (Time Stretched Pulse).

The measurement signal is output through the control unit 100 and the phase adjustment unit 110, and is sequentially output to each speaker SP _FR and SP _FL via the amplification unit 112 (step S12). As a result, predetermined measurement sounds are sequentially output from the respective speakers SP _FR and SP _FL at predetermined time intervals.

In the present embodiment, the driver's seat is the measurement position (listening position) of the impulse response. Therefore, the microphone MIC is installed in the driver's seat. The installation position of the microphone MIC changes according to the listening position. The microphone MIC may be installed in the passenger seat or the rear seat.

The microphone MIC picks up the measurement sound sequentially output from each speaker SP _FR and SP _{FL at} a timing that does not interfere with time. The measurement sound signal (that is, the measurement signal) picked up by the microphone MIC is input to the calculation unit 116 via the signal recording unit 114 (step S13).

FIG. 4 is a block diagram showing the configuration of the calculation unit 116. As shown in FIG. 4, the calculation unit 116 has measurement units 116A and 116B.

The measuring units 116A and 116B measure the impulse response (step S14).

Specifically, the measuring unit 116A calculates a mutual correlation function between the measurement signal of the sound for measurement from the speaker SP _FL (hereinafter referred to as “measurement signal L”) and the measurement signal of the reference, and measures the measurement. The impulse response of the signal L (in other words, the impulse response between the speaker SP _FL and the listening position, hereinafter referred to as “impulse response L'”) is calculated.

In the measuring unit 116B, the mutual correlation function between the measurement signal of the measurement sound from the speaker SP _FR (hereinafter referred to as “measurement signal R”) and the reference measurement signal is obtained by calculation, and the impulse response of the measurement signal R is obtained. (In other words, it is an impulse response between the speaker SP _FR and the listening position, which is hereinafter referred to as "impulse response R'") is calculated.

The reference measurement signal is the same as the measurement signal generated by the measurement signal generation unit 106 and is time-synchronized.

In this way, the measuring units 116A and 116B serve as measuring units for measuring the impulse response of the signal of each sound output from each of the plurality of speakers and picked up at a predetermined listening position at a timing that does not interfere with time. Operate.

FIG. 5 (a) illustrates the impulse response L', and FIG. 5 (b) illustrates the impulse response R'. In each of the figures of FIGS. 5 (a) and 5 (b), the vertical axis represents the amplitude and the horizontal axis represents the time (unit: sec). In the examples of FIGS. 5A and 5B, the sampling frequency is 44.1 kHz, the code length of the M-sequence code is 32,767, and the frequency band is 3 kHz.

Looking at FIGS. 5 (a) and 5 (b), there are many reflections with a short delay time difference due to the special listening environment of the vehicle interior (the sound is blocked by the structure inside the vehicle). Due to the environment where the sound from the speaker interferes, etc.), the suppressed sound first reaches the listening position (in other words, the level of the rising part of the impulse response is low), and the suppressed sound is delayed. , High-level sound reaches the listening position.

As shown in FIG. 4, the calculation unit 116 has Fourier transform units 116C and 116D.

The Fourier transform unit 116C Fourier transforms the impulse response L'input from the measurement unit 116A to obtain the amplitude characteristic and the phase characteristic for each frequency spectrum (step S15). The Fourier transform unit 116D Fourier transforms the impulse response R'input from the measurement unit 116B to obtain the amplitude characteristic and the phase characteristic for each frequency spectrum (step S15).

FIG. 6A is a diagram showing the amplitude characteristics for each frequency spectrum obtained by Fourier transforming the impulse response L', and FIG. 6B is a diagram obtained by Fourier transforming the impulse response R'. It is a figure which shows the amplitude characteristic for every frequency spectrum. In each of FIGS. 6 (a) and 6 (b), the vertical axis represents power (unit: dB) and the horizontal axis represents frequency (unit: Hz).

FIG. 7A is a diagram showing the phase characteristics for each frequency spectrum obtained by Fourier transforming the impulse response L', and FIG. 7B is a diagram obtained by Fourier transforming the impulse response R'. It is a figure which shows the phase characteristic for every frequency spectrum. In each of the figures of FIGS. 7 (a) and 7 (b), the vertical axis represents an angle (unit: degree) and the horizontal axis represents a frequency (unit: Hz).

In the examples of FIGS. 6 (a), 6 (b), 7 (a) and 7 (b), the Fourier transform length is 8,192 samples. The frequency spectrum is set to 4,097 points obtained by dividing the frequency domain from 0 Hz to the Nyquist frequency of 22.05 kHz in increments of 5.38 Hz. The frequency spectrum up to 3 kHz is 557 points. In the examples of FIGS. 6 (a) and 6 (b), the amplitude fluctuates greatly for each frequency because the sound is reflected, shielded, interfered, etc. in the vehicle interior, and FIGS. 7 (a) and 7 (b) In the example of, the phase fluctuates greatly for each frequency.

Hereinafter, for convenience, the amplitude characteristic and phase characteristic for each frequency spectrum of the impulse response L'obtained by the Fourier transform unit 116C are referred to as "frequency spectrum signal L", and the impulse response R'obtained by the Fourier transform unit 116D is described below. The amplitude characteristic and phase characteristic for each frequency spectrum are referred to as "frequency spectrum signal R". The Fourier transform units 116C and 116D operate as Fourier transform units that obtain the frequency spectrum signal of the impulse response for each speaker by Fourier transforming the impulse response of the sound signal from each speaker.

As shown in FIG. 4, the calculation unit 116 has a phase control unit 116E.

The phase control unit 116E performs the following processes (1) to (5) in order to obtain the first amplitude characteristic and the second amplitude characteristic (both of which will be described in detail later) for each frequency spectrum signal L "and R". Do.

<< Processing (1) >>
The phase control unit 116E changes the phase of the frequency spectrum signal (one of the frequency spectrum signal L "and the frequency spectrum signal R" to be processed) in a range of −180 degrees to +180 degrees in a predetermined angle step, and each time the phase is changed. In addition, the frequency spectrum signal to be processed and another frequency spectrum signal (the other of the frequency spectrum signal L "and the frequency spectrum signal R") are combined (step S16). In order to reduce the processing load, this synthesis process is performed not for all frequency spectra but for each frequency spectrum of a total of 557 points up to, for example, 3 kHz.

FIG. 8A is a diagram showing a synthesis result when the frequency spectrum signal L ”is a processing target, and FIG. 8B is a diagram showing a synthesis result when the frequency spectrum signal R” is a processing target. It is a figure. 8 (a) and 8 (b) show the result of synthesizing the frequency spectra of 100 Hz (thick solid line) and 400 Hz (thin solid line) among the frequency spectra of 557 points as representatives. In each of FIGS. 8 (a) and 8 (b), the vertical axis represents the power (unit: dB) of the combined signal, and the horizontal axis represents the phase (unit: degree). The power at 0 degrees of phase (in other words, the phase adjustment amount is zero) indicates the power when the frequency spectrum signal to be processed is combined with another frequency spectrum signal without changing the phase.

<< Processing (2) >>
In each of FIGS. 8A and 8B, the phase of the sound from the speaker SP _FR and the phase of the sound from the speaker SP _FL are in phase at the listening position at the angle at which the power is maximized (listening position). The sound between these speakers causes the strongest interference.) At the angle at which the power is minimized, the phase of the sound from the speaker SP _FR and the phase of the sound from the speaker SP _FL are opposite in the listening position. (The sound between these speakers causes the weakest interference at the listening position.)

In the example of FIG. 8A, in the frequency spectrum of 100 Hz, when the frequency spectrum signal R "without phase adjustment and the frequency spectrum signal L with the phase adjustment amount of -110 degrees are combined at −110 degrees. It becomes in-phase, and becomes out-of-phase at +70 degrees (when the frequency spectrum signal R "without phase adjustment and the frequency spectrum signal L" with a phase adjustment amount of +70 degrees are combined). In the frequency spectrum of 400 Hz, it becomes in phase at +180 degrees (when the frequency spectrum signal R "without phase adjustment and the frequency spectrum signal L with the phase adjustment amount of +180 degrees are combined), and at -10 degrees (phase adjustment). The phase is reversed (when the frequency spectrum signal R "that has not been processed and the frequency spectrum signal L" whose phase adjustment amount is -10 degrees are combined).

In the example of FIG. 8B, in the frequency spectrum of 100 Hz, the frequency spectrum is +110 degrees (when the frequency spectrum signal L "without phase adjustment and the frequency spectrum signal R" with the phase adjustment amount of +110 degrees are combined). The phases are in phase, and the phases are reversed at −70 degrees (when the frequency spectrum signal L ”without phase adjustment and the frequency spectrum signal R” with the phase adjustment amount of −70 degrees are combined). In the frequency spectrum of 400 Hz, it becomes in phase at -180 degrees (when the frequency spectrum signal L "without phase adjustment and the frequency spectrum signal R with the phase adjustment amount of -180 degrees are combined), and at +10 degrees (phase). The phase is reversed (when the unadjusted frequency spectrum signal L "and the frequency spectrum signal R" having a phase adjustment amount of +10 degrees are combined).

The phase control unit 116E is the frequency of the frequency spectrum signal to be processed when the phase of the sound from the speaker SP _FR and the phase of the sound from the speaker SP _FL are in phase at the listening position from the synthesis result for each frequency spectrum. The amount of phase adjustment for each spectrum is obtained (step S17).

FIG. 9A shows a frequency spectrum signal L "when the phase of the sound from the speaker SP _FR and the phase of the sound from the speaker SP _FL are in phase at the listening position in each frequency spectrum from 60 Hz to 3 kHz. 9 (b) shows the phase adjustment amount for each frequency spectrum of the above. FIG. 9B shows the phase of the sound from the speaker SP _FR and the phase of the sound from the speaker SP _FL in each frequency spectrum from 60 Hz to 3 kHz. It is a figure which shows the phase adjustment amount for every frequency spectrum of a frequency spectrum signal R "when it becomes in phase at a listening position. In each of the figures of FIGS. 9A and 9B, the vertical axis represents the phase adjustment amount (unit: degree), and the horizontal axis represents the frequency (unit: Hz).

The frequency range for phase adjustment can be arbitrarily set within the Nyquist frequency range. In the present embodiment, from the lower limit frequency (60 Hz) that can be reproduced by the speakers SP _FR and SP _FL , the frequency at which the phase is audibly dominant in localization (in other words, the frequency that has a large influence on the sound image localization due to the phase shift). ) Is set as the frequency range for phase adjustment (3 kHz).

In the present embodiment, the phase adjustment amount fluctuates greatly for each frequency due to the difference in the propagation delay time for each frequency in the vehicle interior (see FIGS. 9 (a) and 9 (b)).

<< Processing (3) >>
The phase control unit 116E converts the frequency spectrum signal to be processed (frequency spectrum signal L "itself or frequency spectrum signal R" itself) into a complex number, and the phase adjustment amount for each frequency spectrum to be processed obtained in step S17. (See FIG. 9 (a) or FIG. 9 (b)) is converted into a complex number, and these are complex-multiplied (step S18).

<< Processing (4) >>
The phase control unit 116E includes the frequency spectrum signal to be processed (in other words, the phase controlled) complex-multiplied (in other words, phase-controlled) in step S18 and another frequency spectrum signal (frequency spectrum signal L "itself or frequency spectrum signal R" itself). The first amplitude characteristic is obtained by synthesizing and (step S19).

<< Processing (5) >>
The phase control unit 116E transfers the frequency spectrum signal to be processed to another frequency spectrum signal (frequency spectrum signal L "itself or the frequency spectrum signal L" itself without changing the phase (that is, the frequency spectrum signal L "itself or the frequency spectrum signal R" itself). A second amplitude characteristic is obtained by synthesizing with the frequency spectrum signal R "itself) (step S20).

By the above processes (1) to (5), the first amplitude characteristic and the second amplitude characteristic can be obtained for each frequency spectrum signal L ", R". In this way, the phase control unit 116E performs predetermined phase control on each frequency spectrum signal obtained by the Fourier transform unit, and synthesizes the frequency spectrum signal with another frequency spectrum signal that does not perform the predetermined phase control. It operates as an amplitude characteristic calculation unit that obtains one amplitude characteristic and obtains a second amplitude characteristic by synthesizing it with another frequency spectrum signal without performing phase control.

FIG. 10 (a) is a diagram showing the first amplitude characteristic (solid line) and the second amplitude characteristic (broken line) obtained for the frequency spectrum signal L ", and FIG. 10 (b) is a diagram showing the frequency spectrum signal R". It is a figure which shows the 1st amplitude characteristic (solid line) and the 2nd amplitude characteristic (broken line) obtained about. In each of FIGS. 10 (a) and 10 (b), the vertical axis represents the level (unit: dB) and the horizontal axis represents the frequency (unit: Hz).

The phase control unit 116E calculates the level difference between the first amplitude characteristic and the second amplitude characteristic obtained for the frequency spectrum signal L "for each frequency spectrum, and accumulates the calculated level difference for each frequency spectrum. Further, the phase control unit 116E calculates the level difference between the first amplitude characteristic and the second amplitude characteristic obtained for the frequency spectrum signal R "for each frequency spectrum, and accumulates the calculated level difference for each frequency spectrum. To do. The phase control unit 116E compares these cumulative values and detects the speaker corresponding to the larger cumulative value as a speaker satisfying a predetermined condition (step S21). In this way, the phase control unit 116E operates as a detection unit that detects a speaker satisfying a predetermined condition from a plurality of speakers based on the first amplitude characteristic and the second amplitude characteristic obtained for each speaker. ..

FIG. 11A is a diagram showing the level difference between the first amplitude characteristic and the second amplitude characteristic obtained for the frequency spectrum signal L ”for each frequency spectrum, and FIG. 11B is a frequency spectrum signal. It is a figure which shows the 1st amplitude characteristic and the 2nd amplitude characteristic obtained about R', and the level difference for each frequency spectrum. In each of FIGS. 11 (a) and 11 (b), the vertical axis represents the level (unit: dB), and the horizontal axis represents the frequency (unit: Hz).

Here, the first amplitude characteristic is obtained by phase-controlling the frequency spectrum signal of the processing target and synthesizing it with another frequency spectrum signal, and the second amplitude characteristic is the frequency spectrum of the processing target. It was obtained by synthesizing a signal with another frequency spectrum signal without phase control. Therefore, the cumulative value of this level difference is a value indicating the effect when the frequency spectrum signal to be processed is phase-controlled (the effect of increasing the level by reducing the interference of sound weakening between speakers at the listening position). I can say. The higher the cumulative value, the higher this effect.

The cumulative value of the level difference shown in FIG. 11 (a) is 782, and the cumulative value of the level difference shown in FIG. 11 (b) is 2,404. Since the cumulative value obtained for the frequency spectrum signal R "is high, a higher effect (weakening of the sound between the speakers at the listening position) can be achieved by performing the phase adjustment process based on the speaker SP _FR corresponding to the frequency spectrum signal R ". The effect of increasing the level by reducing the interference between the speakers) is obtained, and it is possible to improve the bias of the sound image localization and suppress the deterioration of sound quality and the decrease in sound pressure due to the interference between the sounds output from each speaker. ..

Depending on the arrangement of the speakers and the environment inside the vehicle, the sound from the speaker SP _FR toward the listening position may be suppressed for a longer period of time due to the effects of sound reflection, shielding, interference, and the like. As an example, consider the case where the impulse response R'in FIG. 5 (b) is at a suppressed level for a period of up to 5.0 msec. Even in this case, since the distance from the speaker SP _FR to the listening position (driver's seat) is the shortest, the sound from the speaker SP _FR reaches the listening position in a shorter time than the sound from the speaker SP _FL. (Impulse response R'rises faster than impulse response L'). Therefore, in the conventional time alignment, the sound from the speaker SP _FR is delayed in order to improve the bias of the sound image localization.

However, the rising portion of the impulse response R'is a suppressed level for a period of up to 5.0 msec. Since the sound of this suppressed level is a sound of a weak level, it cannot be said that it is a sound of a practical level that substantially contributes to the localization of the sound image. Practical level sound from the speaker SP _FR , which substantially contributes to the localization of the sound image, reaches the listening position when it exceeds 5.0 msec. On the other hand, looking at FIG. 5A, the sound at a practical level from the speaker SP _FL , which substantially contributes to the localization of the sound image, has reached the listening position at 4.1 msec.

In conventional time alignment, a speaker that takes a long time to reach the listening position at a practical level that substantially contributes to the localization of the sound image (in the example here, a speaker that simply has a quick impulse response rise). Is set as a speaker that gives a delay. Therefore, it is difficult to sufficiently improve the bias of sound image localization by the conventional time alignment.

On the other hand, in the present embodiment, the level of the speaker, which is the reference when executing the phase adjustment processing, is set to a higher effect (the interference of sound weakening between the speakers at the listening position is reduced as described above. By detecting whether or not an increasing effect) is obtained, the bias of sound image localization can be sufficiently improved even in a special listening environment such as in a vehicle interior, and the sound quality deteriorates due to interference between the sounds output from each speaker. It is possible to suppress the decrease in sound pressure.

The phase control unit 116E synthesizes each frequency spectrum obtained for the speaker detected in step S21 (hereinafter referred to as “reference speaker”) (in the present embodiment, synthesizes each frequency spectrum obtained for the speaker SP _FR ). As a result, from FIG. 8B), when the phase of the sound from the speaker SP _FR and the phase of the sound from the speaker SP _FL are out of phase at the listening position, each frequency spectrum of the frequency spectrum signal The phase adjustment amount (first phase adjustment data) is obtained (step S22).

FIG. 12 shows the phase adjustment amount for each frequency spectrum of the frequency spectrum signal R ”when the phase of the sound from the speaker SP _FR and the phase of the sound from the speaker SP _FL are opposite in the listening position (first). It is a figure which shows the phase adjustment data). In FIG. 12, the vertical axis shows the phase adjustment amount (unit: degree), and the horizontal axis shows a frequency (unit: Hz).

As shown in FIG. 4, the calculation unit 116 has a phase shift unit 116F.

The phase shift unit 116F determines the phase adjustment amount for adjusting the phase of the sound signal output to the reference speaker for each frequency spectrum according to the first phase adjustment data (see FIG. 12) (step S23). .. Specifically, the phase adjustment amount for each frequency spectrum is determined according to the following equation.

When | Phc | ≤90 ° Phs = + 90 °
| Phc |> When 90 ° Phs = 0 °
Phc: Phase adjustment amount obtained in step S22 Phs: Phase adjustment amount determined in step S23

FIG. 13 is a diagram showing the amount of phase adjustment for each frequency spectrum determined in step S23. In FIG. 13, the vertical axis represents the phase adjustment amount (unit: degree), and the horizontal axis represents the frequency (unit: Hz).

As shown in FIG. 4, the calculation unit 116 has a smoothing processing unit 116G.

The smoothing processing unit 116G smoothes the phase adjustment amount for each frequency spectrum input from the phase shift unit 116F on the frequency axis (step S24). As a result, phase adjustment data (second phase adjustment data for the reference speaker) for adjusting the phase of the sound signal output to the reference speaker for each frequency spectrum can be obtained.

FIG. 14 is a diagram showing a phase adjustment amount (second phase adjustment data for a reference speaker) after the smoothing process by the smoothing process unit 116G. In FIG. 14, the vertical axis represents the phase adjustment amount (unit: degree), and the horizontal axis represents the frequency (unit: Hz). The smoothing processing unit 116G performs smoothing processing on the phase adjustment amount for each frequency spectrum input from the phase shift unit 116F by an 8-tap FIR (Finite Impulse Response) filter.

The smoothing process by the smoothing process unit 116G suppresses a sudden change in phase in the frequency domain. Therefore, when the phase-adjusted sound is output using the phase-adjusting data, the generation of harmonics due to a sudden change in phase is suppressed, and the audible abnormal noise due to such harmonics is suppressed.

As shown in FIG. 4, the calculation unit 116 has a phase inversion unit 116H.

The phase inversion unit 116H inverts the phase of the phase adjustment amount (second phase adjustment data for the reference speaker) after the smoothing process obtained in step S24, thereby inverting the phase of another speaker (in this embodiment, the present embodiment). A phase adjustment amount (second phase adjustment data for another speaker) for each frequency spectrum for adjusting the phase of the sound signal output to the speaker SP _FL ) is obtained (step S25).

FIG. 15 is a diagram showing the second phase adjustment data for another speaker obtained by the phase inversion unit 116H. In FIG. 15, the vertical axis represents the phase adjustment amount (unit: degree), and the horizontal axis represents the frequency (unit: Hz).

As shown in FIGS. 14 and 15, the second phase adjustment data for the reference speaker is phase-adjusted for each frequency spectrum according to the phase adjustment amount (first phase adjustment data) that becomes the opposite phase. The amount is set in the range of 0 to 90 degrees, and the second phase adjustment data for other speakers is the phase adjustment amount according to the phase adjustment amount (first phase adjustment data) that is out of phase. Is set in the range of 0 degrees to -90 degrees.

In the present embodiment, the second phase adjustment data for each speaker is calculated based on the phase adjustment amount (first phase adjustment data) that is opposite in phase, and the difference between the phase adjustment amounts is 180. Since the second phase adjustment data for each speaker is calculated so as to be within the degree (in other words, the difference in the amount of phase adjustment given to the sound signal output to each speaker is 180 in each frequency spectrum. Since the second phase adjustment data for each speaker is calculated so that it fits within the degree), the position of the driver's seat that is asymmetric with respect to the positions of the pair of speakers SP _FR and SP _FL , also a pair. In both the position of the passenger seat, which is asymmetric with respect to the positions of the speakers SP _FR and SP _FL , it is possible to reduce the interference of sound between the speakers due to the opposite phase, improve the localization, and due to the occurrence of dips. Deterioration of sound quality and decrease of sound pressure are suppressed.

In this way, the phase control unit 116E, the phase shift unit 116F, the smoothing processing unit 116G, and the phase inversion unit 116H reduce the weakening due to sound interference between the plurality of speakers in each frequency spectrum at the plurality of listening positions. In addition, it operates as a generator that generates a second phase adjustment data for adjusting the phase of the sound signal output to each speaker for each frequency spectrum.

The control unit 100 sets the second phase adjustment data for each speaker in the phase adjustment unit 110 (step S26). The phase adjusting unit 110 operates as an adjusting unit that adjusts the phase of the sound signal input from the sound source and output to each speaker for each frequency spectrum by using the second phase adjusting data.

Next, an operation of reproducing the sound signal input from the sound source will be described using the second phase adjustment data set in the phase adjustment unit 110.

The recording medium reproduction unit 108 transmits the sound signals S _R and S _L (hereinafter referred to as “audio signals S _R and S _L ”) input from a sound source such as a CD (Compact Disc) or a DVD (Digital Versatile Disc). Reproduce. The control unit 100 outputs the audio signals S _L and S _R reproduced by the recording medium reproduction unit 108 to the phase adjustment unit 110.

The phase adjusting unit 110 adjusts the phase of the audio signal output to each speaker for each frequency spectrum and outputs the signal. Audio signals output from the phase adjusting section 110 _S R, _{S L,} via an amplifier unit 112, respectively, and output speaker _SP FR, the _{SP FL} to the passenger compartment.

FIG. 16 is a block diagram showing the configuration of the phase adjusting unit 110. As shown in FIG. 16, the phase adjusting unit 110 includes an FFT (Fast Fourier Transform) unit 110A, a complex multiplication unit 110B, and an IFFT (Inverse Fast Fourier Transform) unit 110C.

FFT unit 110A, the audio signal _S R which is input from the control unit 100, after weighting by overlap processing and window function to the _{S L, STFT (Short-Term} Fourier Transform) by the time domain to the frequency domain Is performed, and the frequency spectrum signal composed of the amplitude and the phase is output to the complex multiplication unit 110B. The overlap processing and the window function are for reducing the abnormal noise by gradually changing the phase adjustment amount when the localization position is changed by the user operation (for example, when the driver's seat is changed to the passenger's seat). is there.

In the present embodiment, the FFT unit 110A has a sampling frequency of 44.1 kHz. Further, the FFT unit 110A has a Fourier transform length of 8,192 samples, an overlap length of 6,144 samples, and a window function of a Hanning window. The FFT unit 110A divides the frequency domain from 0 Hz to the Nyquist frequency of 22.05 kHz in increments of 5.38 Hz by performing the SFTT while shifting the time by 2,048 samples, for a total of 4,097 points of frequency spectrum signal. To get.

The second phase adjustment data input from the control unit 100 is set in the complex multiplication unit 110B. The complex multiplication unit 110B performs complex multiplication on the frequency spectrum signal input from the FFT unit 110A for each speaker channel based on the second phase adjustment data, and outputs audio to the speakers of each channel. The phase of the signal is adjusted for each frequency spectrum.

The IFFT unit 110C converts the phase-adjusted frequency spectrum signal input from the complex multiplication unit 110B2 from the frequency domain to the time domain signal by the ISFT, and performs weighting and overlap addition by the window function on the converted signal. , Is output to the amplification unit 112.

17 to 20 show a specific example in the case where the phase is adjusted for each speaker channel. In this example, it is assumed that the audio signal is a monaural impulse signal and the frequency domain is 1 kHz. Interaural time difference affects localization in the low range of 750Hz or less, and interaural phase difference and level difference between both ears affect localization in the low and mid range of 750Hz to 1.5kHz, 1.5kHz or more. It is known that the interaural level difference affects the localization in the mid-high range (see, for example, Japanese Patent Application Laid-Open No. 2004-325284). Therefore, here, the frequency domain for which the phase adjustment is performed is set to 1 kHz. Since the wavelength of 1 kHz or less is relatively long, the interaural phase difference is relatively small. Therefore, here, the sounds reaching the left and right ears of the listener are regarded as the same, and the measurement point for each seat (the listening position where the microphone MIC is installed) is set to one point.

17 (a) and 17 (b) are diagrams showing the time characteristics of the audio signal picked up by the microphone MIC installed in the driver's seat. Specifically, FIG. 17A shows when the audio signals not subjected to the phase adjustment processing according to the present embodiment are simultaneously output from the respective speakers SP _FR and SP _FL (hereinafter, referred to as “example without control”). ), It is a figure which shows the time characteristic of the audio signal picked up by the microphone MIC installed in the driver's seat. FIG. 17B shows the driver's seat when the audio signal subjected to the phase adjustment processing according to the present embodiment is simultaneously output from the speakers SP _FR and SP _FL (hereinafter referred to as “phase adjustment example”). It is a figure which shows the time characteristic of the audio signal picked up by the installed microphone MIC. In each of the figures of FIGS. 17 (a) and 17 (b), the vertical axis represents the amplitude and the horizontal axis represents the time (unit: sec).

18 (a) and 18 (b) are diagrams showing the time characteristics of the audio signal picked up by the microphone MIC installed in the passenger seat. Specifically, FIG. 18A is a diagram showing the time characteristics of an audio signal picked up by a microphone MIC installed in the passenger seat in an example without control. FIG. 18B is a diagram showing the time characteristics of the audio signal picked up by the microphone MIC installed in the passenger seat in the phase adjustment example. In each of the figures of FIGS. 18A and 18B, the vertical axis represents the amplitude and the horizontal axis represents the time (unit: sec).

Comparing FIG. 17A and FIG. 17B, by applying the phase adjustment processing according to the present embodiment to the audio signal, the amplitude is larger than that when the phase adjustment processing according to the present embodiment is not applied to the audio signal. Can be seen to be larger. Further, comparing FIG. 18A and FIG. 18B, by performing the phase adjustment processing according to the present embodiment on the audio signal, the phase adjustment processing according to the present embodiment can be performed on the audio signal even in the passenger seat. It can be seen that the amplitude is larger than when it is not applied to. This is because the phase adjustment processing according to the present embodiment is applied to the audio signal to reduce the weakening due to sound interference between the speaker SP _FR and the speaker SP _{FL at} each listening position (driver's seat, passenger's seat). is there.

FIG. 19 is a diagram showing the frequency characteristics (thin solid line) of the audio signal of the uncontrolled example and the frequency characteristic (thick solid line) of the audio signal of the phase adjustment example picked up by the microphone MIC installed in the driver's seat. .. FIG. 20 is a diagram showing the frequency characteristics (thin solid line) of the audio signal of the uncontrolled example and the frequency characteristic (thick solid line) of the audio signal of the phase adjustment example picked up by the microphone MIC installed in the passenger seat. .. In FIGS. 19 and 20, the vertical axis represents the level (unit: dB) and the horizontal axis represents the frequency (unit: Hz).

As shown in FIGS. 19 and 20, in the phase adjustment example according to the present embodiment, the level is higher over almost the entire area as compared with the non-control example, and the level is higher in any listening position of the driver's seat and the passenger's seat. It can be seen that the weakening due to sound interference between the speaker SP _FR and the speaker SP _FL is reduced as compared with the case without control. In addition, the occurrence of dips is almost suppressed in the frequency domain. Therefore, in the phase adjustment example according to the present embodiment, the bias of the sound image localization is improved at any of the listening positions of the driver's seat and the passenger's seat as compared with the example without control, and between the speaker SP _FR and the speaker SP _FL. It can be seen that the deterioration of sound quality and the decrease in sound pressure due to the interference of the sound of the speaker are suppressed.

The frequency components of voice and music are concentrated in the low and mid range. Therefore, when targeting audio or music audio signals (monaural signals in the low-mid range of 1 Hz or less illustrated here), the sound image localization can be sufficiently improved by simply adjusting the phase of the low-mid range, and the dip can be used. It is possible to suppress the deterioration of sound quality and the decrease of sound pressure due to the generation.

The above is the description of the exemplary embodiment of the present invention. The embodiment of the present invention is not limited to that described above, and various modifications can be made within the scope of the technical idea of the present invention. For example, the embodiment of the present application also includes the content obtained by appropriately combining examples and the like or obvious examples and the like specified in the specification.

The amount of phase adjustment for each frequency spectrum determined by the phase shift unit 116F in step S23 is not limited to that of the above embodiment. The phase shift unit 116F may determine the amount of phase adjustment for each frequency spectrum according to, for example, the following equation.

When | Phc | ≤90 ° Phs = Phc + 90 °
| Phc |> When 90 ° Phs = Phc-90 °

When the phase shift unit 116F determines the phase adjustment amount for each frequency spectrum according to the above equation, the frequency characteristics (fine solid line) and phase of the uncontrolled example audio signal picked up by the microphone MIC installed in the driver's seat. The frequency characteristics (thick solid line) of the audio signal of the adjustment example are shown in FIG. In this case, the frequency characteristics (thin solid line) of the audio signal of the uncontrolled example and the frequency characteristic (thick solid line) of the audio signal of the phase adjustment example, which are picked up by the microphone MIC installed in the passenger seat, are shown in FIG. 22. Shown in. In FIGS. 21 and 22, the vertical axis represents the level (unit: dB) and the horizontal axis represents the frequency (unit: Hz).

As shown in FIGS. 21 and 22, in this case as well, in the phase adjustment example, the level is higher over almost the entire area than in the non-control example, and the level can be increased in any of the listening positions of the driver's seat and the passenger's seat. It can be seen that the weakening due to sound interference between the speaker SP _FR and the speaker SP _FL is reduced as compared with the case without control. In addition, the occurrence of dips is almost suppressed in the frequency domain. Therefore, in this case as well, in the phase adjustment example, the bias of the sound image localization is improved at any of the listening positions in the driver's seat and the passenger's seat as compared with the case without control, and between the speaker SP _FR and the speaker SP _FL It can be seen that the deterioration of sound quality and the decrease in sound pressure due to sound interference can be suppressed.

In the above embodiment, the phase control unit 116E determines the frequency of the frequency spectrum signal when the phase of the sound from the speaker SP _FR and the phase of the sound from the speaker SP _FL are out of phase at the listening position in step S22. The phase adjustment amount for each spectrum is obtained as the first phase adjustment data, but in another embodiment, the phase of the sound from the speaker SP _FR and the phase of the sound from the speaker SP _FL are in phase at the listening position. The phase adjustment amount for each frequency spectrum of the frequency spectrum signal at that time may be obtained as the first phase adjustment data.

In the above embodiment, the acoustic device 10 is equipped with a phase adjustment data generation function (phase control device), but an acoustic device not equipped with the phase adjustment data generation function is also within the scope of the present invention. This sound device holds in advance the second phase adjustment data for each speaker generated in, for example, a manufacturing factory, and is input from a sound source to each speaker using the second phase adjustment data. By adjusting the phase of the output sound signal for each frequency spectrum, the weakening due to sound interference between the plurality of speakers at a plurality of listening positions is reduced in each frequency spectrum.

In another embodiment, the phase adjustment unit 110 Fourier transforms the phase adjustment amount for each frequency spectrum to generate an FIR filter coefficient, and is subject to phase control by processing in the time domain using the FIR filter. The phase of the audio signal output to the speaker may be adjusted for each frequency spectrum. Further, the phase adjustment unit 110 performs division processing for each frequency band based on the phase adjustment amount for each frequency spectrum, and is subject to phase control by an all-pass filter using a secondary IIR (Infinite Impulse Response) filter or the like. The phase of the audio signal output to the speaker may be adjusted.

In the above embodiment, the processing when the impulse response in the driver's seat is measured has been described, but the same processing may be performed for each seat. In this case, the control unit 100 may hold the second phase adjustment data of each speaker generated when the impulse response is measured in each seat as preset data. By operating the operation unit 104 to select preset data, the listener can arbitrarily switch the second phase adjustment data for improving the bias of the sound image localization.

In the above embodiment, the processing when the front speaker is targeted has been described, but when another speaker (for example, a rear speaker) is installed in the vehicle, the same processing is performed on the rear speaker side. May be good.

1 Acoustic system 10 Acoustic device 100 Control unit 102 Display unit 104 Operation unit 106 Measurement signal generation unit 108 Recording medium playback unit 110 Phase adjustment unit 110A FFT unit 110B Complex multiplication unit 110C IFFT unit 112 Amplification unit 114 Signal recording unit 116 Calculation unit 116A, 116B Measuring unit 116C, 116D Fourier transform unit 116E Phase control unit 116F Phase shift unit 116G Smoothing processing unit 116H Phase inversion unit

Claims (16)

A measuring unit that measures the impulse response of each sound signal output from each of a plurality of speakers and picked up at a predetermined listening position at a timing that does not interfere with time.
A Fourier transform unit that obtains a frequency spectrum signal of the impulse response for each speaker by Fourier transforming the impulse response of the sound signal from each of the measured speakers.
A first amplitude characteristic is obtained by performing a predetermined phase control on each of the frequency spectrum signals obtained by the Fourier transform unit and synthesizing the frequency spectrum signal with another frequency spectrum signal in which the predetermined phase control is not performed. In addition, an amplitude characteristic calculation unit that obtains a second amplitude characteristic by synthesizing with the other frequency spectrum signal without performing the phase control,
A detection unit that detects a speaker satisfying a predetermined condition from the plurality of speakers based on the first amplitude characteristic and the second amplitude characteristic obtained for each speaker.
Based on the first phase adjustment data for adjusting the phase of the sound signal output to the detected speaker for each frequency spectrum, at the plurality of listening positions including the predetermined listening position, the plurality of said A second phase adjustment for adjusting the phase of the sound signal output to each of the plurality of speakers for each frequency spectrum so that the weakening due to the interference of the sound between the speakers is reduced in each frequency spectrum. A generator that generates data for
To prepare
Phase control device. The detection unit
The level difference between the first amplitude characteristic and the second amplitude characteristic was calculated for each speaker.
Compare the values according to the level difference calculated for each speaker,
A speaker satisfying the predetermined condition is detected based on the result of the comparison.
The phase control device according to claim 1. The detection unit
The level difference is calculated for each frequency spectrum,
Accumulate the calculated level difference for each frequency spectrum,
The cumulative values of the level differences obtained for each of the speakers were compared and compared.
The speaker having the largest cumulative value is detected as a speaker satisfying the predetermined condition.
The phase control device according to claim 2. The amplitude characteristic calculation unit
The following processes (1) to (5) are performed for each of the frequency spectrum signals obtained by the Fourier transform unit.
(1) The phase of the frequency spectrum signal to be processed is changed, and each time the phase is changed, the frequency spectrum signal to be processed and the other frequency spectrum signal are combined.
(2) Based on the result of the synthesis, the phase adjustment amount of the sound signal from the speaker to be processed is obtained for each frequency spectrum.
(3) The amount of phase adjustment for each frequency spectrum obtained is complexly multiplied by the frequency spectrum signal to be processed.
(4) The first amplitude characteristic is obtained by synthesizing the complex-multiplied frequency spectrum signal and the other frequency spectrum signal.
(5) A second amplitude characteristic is obtained by synthesizing the frequency spectrum signal to be processed and the other frequency spectrum signal without changing the phase.
The phase control device according to any one of claims 1 to 3. The first phase adjustment data is
In the detected speaker, the phase of the sound output from the detected speaker and the phase of the sound output from the other speaker are in phase or out of phase in each frequency spectrum at the listening position. This is data for adjusting the phase of the output sound for each frequency spectrum.
The phase control device according to any one of claims 1 to 4. The generator
Based on the first phase adjustment data, the phase adjustment amount given to the sound signal output to each of the plurality of speakers is calculated for each frequency spectrum.
The calculated phase adjustment amount for each frequency spectrum is obtained as the second phase adjustment data.
The phase control device according to claim 5. The generator
The phase adjustment amount is calculated so that the difference in the phase adjustment amount given to the sound signal output to each of the plurality of speakers is within 180 degrees in each frequency spectrum.
The phase control device according to claim 6. An acoustic device having the phase control device according to any one of claims 1 to 7, and outputting a sound signal input from a sound source to the plurality of speakers.
Using the second phase adjustment data, an adjustment unit for adjusting the phase of a sound signal input from the sound source and output to each of the plurality of speakers for each frequency spectrum is provided.
Acoustic device. A phase control method performed by a computer
A measurement step of measuring the impulse response of each sound signal output from each of a plurality of speakers and picked up at a predetermined listening position at a timing that does not interfere with time.
A Fourier transform step of obtaining a frequency spectrum signal of the impulse response for each speaker by Fourier transforming the impulse response of the sound signal from each of the measured speakers.
The first amplitude characteristic is obtained by performing a predetermined phase control on each of the frequency spectrum signals obtained in the Fourier transform step and synthesizing the frequency spectrum signal with another frequency spectrum signal in which the predetermined phase control is not performed. In addition, the amplitude characteristic calculation step of obtaining the second amplitude characteristic by synthesizing with the other frequency spectrum signal without performing the phase control,
A detection step of detecting a speaker satisfying a predetermined condition from the plurality of speakers based on the first amplitude characteristic and the second amplitude characteristic obtained for each speaker.
Based on the first phase adjustment data for adjusting the phase of the sound signal output to the detected speaker for each frequency spectrum, at the plurality of listening positions including the predetermined listening position, the plurality of said A second phase adjustment for adjusting the phase of the sound signal output to each of the plurality of speakers for each frequency spectrum so that the weakening due to the interference of the sound between the speakers is reduced in each frequency spectrum. Generation steps to generate data for
including,
Phase control method. In the detection step
The level difference between the first amplitude characteristic and the second amplitude characteristic was calculated for each speaker.
Compare the values according to the level difference calculated for each speaker,
A speaker satisfying the predetermined condition is detected based on the result of the comparison.
The phase control method according to claim 9. In the detection step
The level difference is calculated for each frequency spectrum,
Accumulate the calculated level difference for each frequency spectrum,
The cumulative values of the level differences obtained for each of the speakers were compared and compared.
The speaker having the largest cumulative value is detected as a speaker satisfying the predetermined condition.
The phase control method according to claim 10. In the amplitude characteristic calculation step
The following processes (1) to (5) are performed for each of the frequency spectrum signals obtained in the Fourier transform step.
(1) The phase of the frequency spectrum signal to be processed is changed, and each time the phase is changed, the frequency spectrum signal to be processed and the other frequency spectrum signal are combined.
(2) Based on the result of the synthesis, the phase adjustment amount of the sound signal from the speaker to be processed is obtained for each frequency spectrum.
(3) The amount of phase adjustment for each frequency spectrum obtained is complexly multiplied by the frequency spectrum signal to be processed.
(4) The first amplitude characteristic is obtained by synthesizing the complex-multiplied frequency spectrum signal and the other frequency spectrum signal.
(5) A second amplitude characteristic is obtained by synthesizing the frequency spectrum signal to be processed and the other frequency spectrum signal without changing the phase.
The phase control method according to any one of claims 9 to 11. The first phase adjustment data is
In the detected speaker, the phase of the sound output from the detected speaker and the phase of the sound output from the other speaker are in phase or out of phase in each frequency spectrum at the listening position. This is data for adjusting the phase of the output sound for each frequency spectrum.
The phase control method according to any one of claims 9 to 12. In the generation step
Based on the first phase adjustment data, the phase adjustment amount given to the sound signal output to each of the plurality of speakers is calculated for each frequency spectrum.
The calculated phase adjustment amount for each frequency spectrum is obtained as the second phase adjustment data.
The phase control method according to claim 13. In the generation step
The phase adjustment amount is calculated so that the difference in the phase adjustment amount given to the sound signal output to each of the plurality of speakers is within 180 degrees in each frequency spectrum.
The phase control method according to claim 14. When the sound signal input from the sound source is output to the plurality of speakers, the sound signal input from the sound source and output to each of the plurality of speakers is used by using the second phase adjustment data. Further includes an adjustment step of adjusting the phase of the frequency spectrum for each frequency spectrum.
The phase control method according to any one of claims 9 to 15.

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