JP2000261900A - Sound field correction method and acoustic device. - Google Patents

Abstract

(57) [Summary] An object of the present invention is to provide a sound field correction method and an acoustic device that control standing waves at all listening positions and correct frequency characteristics. SOLUTION: The acoustic device includes microphones 21 to 24 installed at arbitrary positions in a room 2, a speaker 3LF installed at a predetermined position in the room, measuring acoustic characteristics at the positions, analyzing the measured values. 3RF, 3LB, 3RB,
Speakers 3LF, 3RF, 3LB, 3R based on analysis values
And a system control circuit 41 for controlling the audio signal supplied to B. The system control circuit 41 controls a standing wave at an arbitrary listening position and corrects the frequency characteristic. The characteristics can be made flat, and the sound pressure level at the measurement position can be made close to a constant, whereby the sound pressure difference in the observation plane can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound field correction method and a sound apparatus for correcting a sound field in a vehicle, for example.

[0002]

2. Description of the Related Art Hitherto, a control technique for adjusting the acoustic characteristics of the interior of a vehicle has been proposed. A typical control technique is to remove a standing wave (Japanese Patent Laid-Open No. 9-327086).
And optimization of delay time (Japanese Patent Laid-Open No. 10-161667).

[0003] First, the technology of removing standing waves is disclosed in
As described in Japanese Patent No. 327086, sound output from a speaker is collected as being close to the original sound to form a sound field in which the influence of reflected sound in a room is removed, and the sound is output from the speaker. Pick up the sound just before that,
The sound pressure level of the collected sound is adjusted by the first correction means so as to be within ± 4 dB over substantially the entire audible frequency band, and the sound pressure level of the sound collected at a desired sound receiving point is audible. The adjustment is performed by the second correction means so as to fall within ± 4 dB over substantially the entire frequency band. According to this method, the sound pressure level is adjusted for the sound immediately after the output of the speaker, and the sound very close to the original sound reflecting the influence of the increase in the sound pressure level in the low frequency band can be reproduced.

[0004] Second, a technique for optimizing the delay time is disclosed in Japanese Patent Laid-Open No. 10-161667.
The signal propagation time of the non-control band in the vehicle interior acoustic space is measured in a short time, and a desired delay time is set in the delay unit. The adaptive signal processing unit in the delay time determination unit executes the adaptive signal processing. Simulates the signal propagation type in the non-control band in the vehicle interior acoustic space with an adaptive filter, and calculates the maximum coefficient /
The delay time search unit obtains the peak position of the signal propagation type impulse response with reference to the coefficient value of the adaptive filter, obtains the signal propagation time from the peak position, and calculates the signal propagation time of the control band and the signal propagation time of the non-control band. Is set as a delay time in the delay device, so that the audio signal in the control band and the audio signal in the non-control band reach the observation point at the same time.

[0005]

However, the above-described conventional technique for controlling acoustic characteristics does not control all frequency characteristics of a listening point. In other words, there is a disadvantage that the frequency characteristics of the driver's seat can be controlled in the passenger compartment, but the control is insufficient in the passenger seat.

[0006] In addition, the technique for optimizing the delay time described in Japanese Patent Application Laid-Open No. 10-161667 discloses a technique in which a second speaker for correction is provided separately from a first speaker, and only the speaker for correction is corrected. Therefore, it is required to correct all speakers, but there is an inconvenience that there is no technology that satisfies this.

In addition, a sound field correction system that has been put into practical use requires a super woofer and a large number of speakers (for example, five or more), so that there is a disadvantage that the type of mounted vehicle is limited.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to provide a sound field correction method and an audio apparatus for controlling a standing wave at a listening position and correcting a frequency characteristic. .

[0009]

According to a sound field correction method of the present invention, a microphone is installed at an arbitrary position in a room, acoustic characteristics at the position are measured, the measured values are analyzed, and a sound value is analyzed based on the analyzed values. Further, by controlling an audio signal supplied to a speaker installed at a predetermined position in the room, a standing wave is controlled at an arbitrary listening position, and a frequency characteristic is corrected.

[0010] Further, the acoustic device of the present invention includes a microphone installed at an arbitrary position in a room, a measuring device for measuring acoustic characteristics at the position, an analyzing device for analyzing the measured value, and a predetermined device in the room. A speaker installed at a position, and control means for controlling an audio signal supplied to the speaker based on the analysis value, and controlling a standing wave at an arbitrary listening position to correct a frequency characteristic. Things.

Therefore, according to the present invention, the following operations are performed. In order to set each digital filter of the control means, a random signal is trial-reproduced using an adjustment disk. Next, the reproduced sound of the trial reproduction is collected by using each microphone and converted into digital data. Then, the digital data is taken into the system control circuit of the measuring means, and the system control circuit of the control means performs a predetermined operation. Then, the coefficients of each digital filter are determined, and each digital filter is subjected to acoustic processing.

At least as many FIR digital filters as the number of loudspeakers are mounted on the control means, and predetermined acoustic processing is performed by setting a coefficient value supplied from a system control circuit of the control means. For example, four digital filters are used to control output sounds of four speakers. Note that four microphones are used to measure acoustic characteristics for controlling output sounds of the four speakers.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Analysis of Acoustic Processing] Before describing the present embodiment in detail, an outline of acoustic processing performed in the present embodiment will be described. 2. Description of the Related Art In recent years, with the improvement of vibration proof performance of on-vehicle audio equipment, the importance of an audio listening space in a vehicle interior has been increasing. However, listening environment and acoustic characteristics are very different from home,
Research on listening environments has been widely conducted for these improvements. Also, a technique for improving acoustic characteristics using a graphic equalizer or an adaptive filter has been proposed and commercialized. However, proposals for a method of improving the acoustic characteristics at all listening positions by examining the acoustic mode have not been made so far.

The inventors of the present application have compared experimental results with analysis results by the finite element method using a vehicle interior model, and confirmed that acoustic characteristics can be accurately obtained. In addition, the acoustic mode was visualized, and the frequency characteristics were improved using a correction filter that considered the acoustic mode.

[Acoustic Characteristics of Vehicle Interior by Finite Element Method] First, the acoustic characteristics of vehicle interior by the finite element method were analyzed.
In order to clarify the accuracy of the analysis model, a typical frequency response ratio function (FRRF) when the interior space is assumed to be a rigid wall in a 1/3 scale acrylic 1/3 scale interior model shown in FIG. The experiment and the analysis of) were performed. The observation surface is the position of the passenger's ear, and the observation points are the left ear positions of the right rear seat, the left rear seat, the right front seat, and the left ear of the front seat (hereinafter referred to as points A, B, C, and D in this order). ). The studied frequency is lower than 600 [Hz] where the fundamental sound mode in the vehicle cabin appears in the low-frequency range of audio (20 Hz in an actual vehicle).
0 [Hz] or less).

Next, the frequency characteristic of the point A when the analysis model was brought close to the actual vehicle in consideration of the sound absorption characteristics was obtained. As shown in FIG. 2, the analytic model has four loudspeakers arranged symmetrically, and the admittance obtained from the known specific acoustic impedance ratio of the actual vehicle is known on the six sound absorbing walls constituting the cabin space. Value applied. Below, this characteristic is examined.

[Application of Correction Filter] When there is a node of a mode to be described later at the listening position such as the front seat, the mode cannot be reproduced. Further, it is difficult to make the frequency characteristics flat at a plurality of positions only by changing the speaker installation position.

Therefore, in the present embodiment, the frequency characteristic is made flat by applying a correction filter using the inverse characteristic of the frequency characteristic between the speaker and the listening position. In the present embodiment, four frequency characteristics of A, B, C, and D are independently controlled by four speakers. By applying the correction filter, the frequency characteristic of the passenger compartment changed, and the frequency characteristic of the position of the occupant's ear became flat. In addition, the sound pressure levels at the four locations described above approached a certain level. Specifically, by applying the correction filter, the sound pressure difference in the observation plane could be stabilized from 26 [dB] on average to 18 [dB] to 8 [dB].

As described above, the improvement of the frequency characteristic by the correction filter was examined using the 1/3 scale model. By controlling the four loudspeakers by applying the correction filter, the frequency characteristic of the observation point of 200 [Hz] or less was flattened, and the sound pressure difference in the observation plane could be reduced.

[Configuration of Acoustic Apparatus] The present embodiment will be described below. First, the configuration of the acoustic device of the present embodiment is shown in FIG.
This will be described with reference to FIG. The acoustic device of the present embodiment
This is applied when correcting the sound field in the room of the vehicle.

Hereinafter, the configuration of the optical disk reproducing unit 10 as an acoustic device will be described. In FIG. 1, an optical disk reproducing unit 10 includes, in a signal processing system, an optical pickup 11 for reading a signal from a disk D, and an RF signal processing circuit 14 for amplifying a signal read by the optical pickup 11 at a high frequency and outputting an RF reproduced signal. A demodulation DSP 16 that performs error correction or the like on the RF reproduction signal and outputs an audio signal; an audio DSP 20 that performs predetermined audio processing on the audio signal;
Amplifying circuits 31 to 34 for amplifying the audio signal subjected to the audio processing by 0, and speakers 3LF, 3RF, 3LB, 3R arranged in the cabin 2 of the automobile 1 and outputting reproduced sounds.
B.

The audio DSP 20 includes four speakers 3LF, 3RF, 3L in the audio processing system.
In order to control the output sounds of B and 3 RBs, four digital filters 25 to 28 are provided.

The optical disk reproducing unit 10 includes four speakers 3LF, 3RF,
Four microphones 21 to 24 for measuring acoustic characteristics for controlling output sounds of 3LB and 3RB, and audio signals collected by using the microphones 21 to 24 are amplified and converted into digital data. Amplifier (AM
P) and an analog-to-digital converter (A / D) 44;
A system control circuit 41 that takes in the converted digital data, performs a predetermined operation, determines the coefficients of the digital filters 25 to 28, and performs acoustic processing on the digital filters 25 to 28, and a reproducing operation for the optical disk reproducing unit 10. And an operation key group 42 for performing a key input operation corresponding to the instruction, and a display 43 which is a display unit for displaying the operation content.

The optical disk reproducing unit 10 includes a reproducing unit control circuit 17 for extracting a clock signal at the time of demodulating an RF reproduction signal and supplying the extracted clock signal to a servo control circuit 15 in a servo system. Spindle motor 12 based on the speed signal and the speed error signal (VE).
And a servo control circuit 15 for supplying a drive signal to the feed motor 13 and supplying a drive signal to the biaxial actuator of the optical pickup 11 based on the tracking error signal (TE) and the focus error signal (FE) to perform servo control. And a spindle motor 12 for rotating the disk D and a feed (thread) for sequentially moving the optical pickup 11 from the inner circumferential direction to the outer circumferential direction of the disk D.
And a motor 13.

[Operation of Acoustic Apparatus] The acoustic apparatus configured as described above operates as follows. In FIG.
The optical pickup 11 reads a signal from the disk D. The signal read by the optical pickup 11 is R
High-frequency amplification by the F signal processing circuit 14 and demodulation DS
Processing such as error correction is performed by P16, and the resulting signal is supplied to the audio DSP 20 as an audio signal. Also,
The RF reproduction signal at the time of demodulation is supplied to the reproduction unit control circuit 17.

The spindle motor 12 has a disk D
And the feed (thread) motor 13 moves the optical pickup 11 sequentially from the inner circumferential direction to the outer circumferential direction of the disk D. The servo control circuit 15 supplies a drive signal to the spindle motor 12 and the feed motor 13 to perform servo control. The servo control circuit 15 generates a drive signal based on a clock signal extracted from the RF reproduction signal in the reproduction section control circuit 17. In addition, in addition to the above, the reproduction section control circuit 17 also performs communication with a system control circuit (microcomputer (microcomputer)) 41 and controls mechanical mechanisms such as a loading mechanism and a feeding mechanism for the disk D.

The optical disk reproducing unit 1 is operated by the operation key group 42.
When a key input operation corresponding to a playback operation instruction for 0 is performed, the operation of displaying the above-described disc D is executed after the operation content is displayed on the display 43 as a display unit.

More specifically, the reproducing section control circuit 17 generates a control signal based on a command from the system control circuit 41 and supplies the control signal to the servo control circuit 15. The servo control circuit 15 supplies a drive signal to the spindle motor 12, the feed motor 13 and the optical pickup 11 to perform servo control. Thereby, the spindle motor 12
Rotates the disk D, and the feed motor 13 moves the optical pickup 11 sequentially from the inner circumferential direction to the outer circumferential direction of the disk D.

At a predetermined position, a laser beam is emitted from the optical pickup 11 to the disk D, and focus servo is performed using the focus coil of the biaxial actuator of the optical pickup 11.
The tracking servo is applied using the tracking coil of the axis actuator. In this way, after each servo is applied, the signal is read and the digital audio signal is reproduced.

First, the innermost TOC of the disk D (Ta
After reading information such as the start and end addresses of ble of contents, the music (track) is reproduced. In this way, the reproduction of the track is executed, and the digital audio data is supplied to the audio DSP 20. In the audio DSP 20, predetermined audio processing described later is performed on the audio data. The audio data subjected to the audio processing by the audio DSP 20 is converted into an analog audio signal, amplified by the amplifier circuits 31 to 34, and reproduced from the speakers 3LF, 3RF, 3LB, 3RB arranged in the cabin 2 of the automobile 1. Output as sound.

[Operation of Digital Filter] In this embodiment, in particular, FIR digital filters 25 to 28 are provided in the audio DSP 20 by the speakers 3LF and 3R.
F, 3LB, 3RB or more are mounted, and predetermined acoustic processing is performed by setting the coefficient value supplied from the system control circuit 41. In FIG. 1, 4
An example is shown in which four digital filters 25 to 28 are mounted to control output sounds of the three speakers 3LF, 3RF, 3LB, and 3RB. The four speakers 3LF, 3
Four microphones 21 to 24 are used to measure acoustic characteristics for controlling output sounds of RF, 3LB, and 3RB.

In the actual control, first, a random signal is trial-reproduced using an adjustment disk in order to set the digital filters 25 to 28. Next, the reproduced sound of the test reproduction is collected by using each of the microphones 21 to 24 and converted into digital data by an amplifier (AMP) and an analog-to-digital converter (A / D) 44, and then transmitted to the system control circuit 41. The digital data is fetched, a predetermined operation is performed, the coefficient of each digital filter is determined, and each digital filter is subjected to acoustic processing. The method for obtaining the characteristics of each digital filter will be described later in detail.

[Application Example] In the present embodiment described above, an example is shown in which the system control unit 41 of the optical disk reproducing unit 10 sets the coefficient values of the digital filters 25 to 28. The coefficient value is read out from the external semiconductor memory in which the coefficient is also stored and the digital filter 2
You may make it supply to 5-28. Further, the coefficient value may be read out by reproducing the disk D on which the coefficient value is recorded and stored in a flash ROM or the like. Further, the coefficient values may be recorded and supplied to a floppy disk or a magneto-optical recording medium (MO, MD).

In the above-described embodiment, an example is shown in which four microphones 21 to 24 are used to measure acoustic characteristics for controlling output sounds of four speakers 3LF, 3RF, 3LB, and 3RB. However, the present invention is not limited to this, and measurement may be performed four times at a position corresponding to four microphones using one microphone.

[Method for Obtaining Characteristics of Each Digital Filter] Next, a method for obtaining characteristics of each digital filter will be described. FIG. 2 shows a simulation model of the present embodiment.
In Fig. 2, four speakers 3LF, 3RF, 3LB,
The simulation surface 50 was set as shown in FIG. 2 in order to analyze the acoustic characteristics by 3RB. The simulation surface 50 in FIG. 2 is a surface corresponding to the height of the crew member's ear in the actual vehicle.

FIG. 3 shows how to determine the characteristics of each digital filter according to the present embodiment. For example, in FIG.
Assuming that each of the sound sources 1 to F4 is a sound source and X1 is a response point, the response point X1 is expressed by a transfer function H ** established between each of the sound sources F1 to F4 and the response point X1 as follows.

[0037]

X1 = H11 × F1 + H12 × F2 + H13 ×
F3 + H14 × F4

Here, H ** is a transfer function H (S). Therefore, the phase characteristics also need to be controlled. Further, the terms are treated as not dependent on one another.

Therefore, if a similar expression can be considered for each response point (X1 to X4), the determinant shown in the upper right of FIG. 3 is obtained. Thus, the sound sources F1 to F4 are represented as a determinant at the lower right of FIG. 3, and the characteristics of the sound source can be obtained by solving the inverse matrix with X1 = X2 = X3 = X4 = constant. Assuming that the frequency characteristics of the speakers 3LF, 3RF, 3LB, and 3RB are flat, the sound sources F1 to F4 have the characteristics of the filter of the control system desired to be obtained. For example, the frequency characteristics of each filter can be obtained by solving the above determinant by the least square method or the like for each frequency.

[Example of actual setting] In actual setting,
For example, an M-sequence signal (pseudo-random signal) or the like is generated from a speaker, and an impulse response in the vehicle compartment is obtained based on a cross-correlation between a microphone output (reproduction signal) and a response in the vehicle compartment. When a frequency characteristic is obtained by performing FET operation on the obtained impulse response, the frequency characteristic of the filter is obtained so as to satisfy the above determinant. FIG. 10A shows the frequency characteristic (target value) of the sound source on the driver's seat side obtained from the measurement data thus obtained. The coefficients of the digital filter are set so as to satisfy this frequency characteristic. FIG.
OB indicates a frequency characteristic obtained by appropriately selecting a coefficient of the digital filter for the sound source on the driver's seat side.

[Example of Simulation Result] As shown in FIG. 2, the simulation was performed by setting four sound sources at four positions corresponding to the left and right front speakers and rear speakers of the actual vehicle. FIG. 4 shows the response of the driver's seat and the response of the passenger's seat without filtering according to the present embodiment. FIG. 5 shows the sound pressure distribution at the frequency of the acoustic mode without filtering according to the present embodiment. FIG.
Shows the sound pressure distribution when the simulation surface 50 of FIG. 2 is viewed from above and the front of the model is on the left side.

When each sound source is set to the same sound pressure (100 [dB]), the driver's seat shown in FIG. 4A and the passenger's seat shown in FIG. 4B have peaks of about 30 [dB] at the maximum.
It can be seen that the fluctuation is large above 00 [Hz]. Modes (Modes) 1 to 10 shown in FIG. 5 correspond to the respective acoustic modes and indicate the respective standing waves. The frequency of each mode is mode: 243 Hz, mode 2: 306H
z, mode 3: 390 Hz, mode 4: 453 Hz, mode 5: 528 Hz, mode 6: 549 Hz, mode 7: 615 Hz, mode 8: 624 Hz, mode 9: 6
36 Hz and mode 10: 657 Hz (the same applies to the following figures).

FIG. 6 shows the response of the driver's seat and the sound source at the driver's seat side front in a state where the filter is applied according to the present embodiment. FIG. 7 shows the sound pressure distribution at the frequency of the acoustic mode with the filter applied according to the present embodiment. In FIG. 7, the response points (measurement points) are set as black circles on mode 1. This point corresponds to the positions of the left ear and the right ear of the driver and the passenger in the passenger seat. In the response of the driver's seat shown in FIG. 6A, it can be seen that the frequency characteristics are controlled to be flat at the positions of the left and right ears. Here, although not particularly shown, similar results are obtained in the passenger seat. The sound source at the driver's seat shown in FIG. 6B is the frequency characteristic of the filter of the sound source at the driver's seat side front. In the sound pressure distribution shown in FIG. 7, the sound pressure is generally uniform as compared with the case without a filter, and the sound pressure at the measurement point (the position of each passenger's ear) is controlled to be flat.

FIG. 8 shows the response of the driver's seat and the sound source at the driver's seat side front with the filter applied at another response point of the present embodiment. FIG. 9 shows a sound pressure distribution at a frequency of an acoustic mode in a state where a filter is applied at another response point of the present embodiment. In FIG. 9, response points (measurement points)
Was set as a black circle on mode 1. This point corresponds to the position of the left ear of all the passengers (four). In the response of the driver's seat shown in FIG. 8A, it is understood that the frequency characteristics are controlled to be flat at the positions of the left and right ears. The sound source of the driver's seat shown in FIG. 8B is the frequency characteristic of the filter of the sound source on the driver's seat side front. In the sound pressure distribution shown in FIG. 9, the sound pressure distribution is non-uniform in modes 7 and 10, but the sound pressure is stable over all the modes only at the measurement points (around the position of the occupant's ear). I understand.

The sound field correction method of the present embodiment described above
Microphones 21 to 24 are installed at arbitrary positions in the room 2, acoustic characteristics at the positions are measured, the measured values are analyzed, and a speaker 3 LF is installed at a predetermined position in the room 2 based on the analysis values. , 3RF, 3LB, 3RB, the standing wave is controlled at an arbitrary listening position, and the frequency characteristic is corrected. Therefore, the indoor frequency characteristic is changed to change the frequency at the observation position. The characteristics can be made flat, and the sound pressure level at the measurement position can be made close to a constant, whereby the sound pressure difference in the observation plane can be reduced.

In the sound field correction method according to the present embodiment, since the measurement position is set at the listening position in the above description,
The frequency characteristics of the ear position, which is the listening position of the listener, can be flattened, and the sound pressure level at the measurement position can be made constant, thereby reducing the sound pressure difference in the observation plane. Can be.

In the sound field correcting method of the present embodiment, the same number of speakers 3 LF and 3
By controlling the frequency characteristics of RF, 3LB, and 3RB, the frequency characteristics of the measurement point are corrected, so that the frequency characteristics of an arbitrary listening position can be made flat, and the sound pressure level of the measurement position can be kept constant. , So that the sound pressure difference in the observation plane can be reduced.

In the sound field correcting method according to the present embodiment, the frequency characteristics of the listening positions in substantially the entire area of the room 2 are corrected in the above description, so that the frequency characteristics of all the listening positions in the room 2 are flattened. Thus, the sound pressure difference in the observation plane can be reduced.

In the sound field correcting method according to the present embodiment, since the room 2 is the room 2 of the vehicle 1 in the above description,
In a vehicle room where standing waves are likely to be generated in the sound field, the frequency characteristics of the observation position can be made flat, and thereby the sound pressure difference in the observation plane can be reduced.

The acoustic device according to the present embodiment is a
Microphones 21 to 24 installed at arbitrary positions of
A system control circuit 41 as measurement means for measuring acoustic characteristics at the position, a system control circuit 41 as analysis means for analyzing the measurement values, and speakers 3LF, 3RF, 3LB, 3R
B and the loudspeakers 3LF, 3R based on the analysis values
And a system control circuit 41 as control means for controlling audio signals supplied to the F, 3LB, and 3RB, and controls a standing wave at an arbitrary listening position to correct a frequency characteristic. Can be changed to make the frequency characteristic of the observation position flat, and the sound pressure level at the measurement position can be made closer to a constant, thereby reducing the sound pressure difference in the observation plane.

Further, in the acoustic device of the present embodiment, in the above description, the measurement position by the system control circuit 41 as the measuring means is set at the listening position, so that the frequency characteristic of the ear position, which is the listening position of the listener, is set. Can be made flat, and the sound pressure level at the measurement position can be made close to a constant, whereby the sound pressure difference in the observation plane can be reduced.

Further, in the acoustic device of the present embodiment, the system control circuit 41 as the control means in the above description
Are the same number of speakers 3LF, 3RF, 3LB, 3 as the number of measurement points by the system control circuit 41 as the measurement means.
By controlling the frequency characteristic of the RB, the frequency characteristic of the measurement point is corrected, so that the frequency characteristic of any listening position can be made flat, and the sound pressure level of the measurement position can be made constant. Thus, the sound pressure difference in the observation plane can be reduced.

Further, in the acoustic device according to the present embodiment, the system control circuit 41 as the control means described above is used.
Corrects the frequency characteristics of the listening positions in substantially the entire area of the room, so that the frequency characteristics of all the listening positions in the room can be flattened, thereby reducing the sound pressure difference in the observation plane. .

Further, in the acoustic device of the present embodiment, the system control circuit 41 as the control means in the above description
Are arithmetic means and FIR type digital filters 25 to 28 which are equal to or more than the number of speakers 3LF, 3RF, 3LB, 3RB for controlling supplied audio signals.
Therefore, even when the number of speakers is increased, the frequency characteristics of an arbitrary listening position can be made flat by using a number of FIR digital filters corresponding to the number of speakers. The pressure level can be made closer to a constant, thereby reducing the sound pressure difference in the observation plane.

Further, in the acoustic device of the present embodiment, in the above description, the calculating means calculates the coefficients in the FIR digital filters 25 to 28, so that the transfer function has the inverse characteristic of the transfer function of the sound source at the measurement point. By calculating the coefficient, the frequency characteristics at any listening position can be flattened, and the sound pressure level at the measurement position can be made constant, thereby reducing the sound pressure difference in the observation plane. can do.

In the acoustic device of the present embodiment, in the above description, since the room 2 is the room 2 of the vehicle 1, the frequency characteristic of the observation position in the vehicle room 2 where a standing wave is likely to be generated in the sound field. Can be made flat, so that the sound pressure difference in the observation plane can be reduced.

[0057]

According to the sound field correction method of the present invention, a microphone is installed at an arbitrary position in a room, acoustic characteristics at the position are measured, the measured values are analyzed, and the room is analyzed based on the analyzed values. By controlling the audio signal supplied to the speaker installed at the predetermined position, the standing wave is controlled at an arbitrary listening position, and the frequency characteristics are corrected. Can be flattened, and the sound pressure level at the measurement position can be made close to a constant, whereby the sound pressure difference in the observation plane can be reduced.

According to the sound field correcting method of the present invention, in the above description, since the measurement position is set at the listening position, the frequency characteristics of the ear position, which is the listening position of the listener, can be made flat, and In addition, the sound pressure level at the measurement position can be made close to a constant value, thereby providing an effect that the sound pressure difference in the observation plane can be reduced.

In the sound field correction method of the present invention, the frequency characteristics of the measurement points are corrected by controlling the frequency characteristics of the same number of speakers as the number of the measurement points. The characteristics can be made flat, and the sound pressure level at the measurement position can be made close to a constant, whereby the effect of reducing the sound pressure difference in the observation plane can be obtained.

Further, in the sound field correcting method of the present invention, the frequency characteristics of the listening positions in substantially the entire area in the room are corrected in the above description, so that the frequency characteristics of all the listening positions in the room can be made flat. Thereby, there is an effect that the sound pressure difference in the observation plane can be reduced.

According to the sound field correction method of the present invention, in the above description, since the room is a vehicle room, the frequency characteristic of the observation position is made flat in a vehicle room where standing waves are likely to be generated in the sound field. Accordingly, there is an effect that the sound pressure difference in the observation plane can be reduced.

Further, the acoustic device of the present invention includes a microphone installed at an arbitrary position in a room, a measuring device for measuring acoustic characteristics at the position, an analyzing device for analyzing the measured value, and a predetermined device in the room. A speaker installed at a position, and control means for controlling an audio signal supplied to the speaker based on the analysis value, and controlling a standing wave at an arbitrary listening position to correct a frequency characteristic. Therefore, by changing the frequency characteristics of the room, the frequency characteristics at the observation position can be made flat, and the sound pressure level at the measurement position can be made closer to a constant value. This has the effect of being able to reduce.

Further, in the acoustic device of the present invention, in the above, the measurement position by the measuring means is set at the listening position, so that the frequency characteristic of the ear position, which is the listening position of the listener, can be made flat, In addition, the sound pressure level at the measurement position can be made close to a constant value, thereby providing an effect that the sound pressure difference in the observation plane can be reduced.

Further, in the acoustic apparatus of the present invention, in the above, the control means corrects the frequency characteristics of the measurement points by controlling the frequency characteristics of the same number of speakers as the number of measurement points by the measurement means. The frequency characteristics at an arbitrary listening position can be made flat, and the sound pressure level at the measurement position can be made close to a constant value, whereby the sound pressure difference in the observation plane can be reduced. .

Further, in the acoustic device of the present invention, in the above, the control means corrects the frequency characteristics of the listening positions in substantially the entire area of the room, so that the frequency characteristics of all the listening positions in the room are made flat. Accordingly, there is an effect that the sound pressure difference in the observation plane can be reduced.

Further, in the acoustic device of the present invention, in the above, the control means has the arithmetic means and the number of FIR digital filters equal to or more than the number of speakers for controlling the supplied audio signal. In the case of additional speakers, the number of FIRs corresponding to the number of speakers
Using a digital filter, the frequency response at any listening position can be made flat, and the sound pressure level at the measurement position can be made constant, thereby reducing the sound pressure difference in the observation plane. It has the effect of being able to do so.

In the acoustic device of the present invention, in the above, since the calculating means calculates the coefficient in the FIR digital filter, the calculating means calculates the coefficient so as to have the inverse characteristic of the transfer function of the sound source at the measurement point. This makes it possible to flatten the frequency characteristics of an arbitrary listening position and to make the sound pressure level at the measurement position close to a constant, thereby reducing the sound pressure difference in the observation plane. It works.

In the acoustic device of the present invention, in the above description, since the room is a vehicle room, the frequency characteristic of the observation position can be made flat in a vehicle room where standing waves easily occur in the sound field. Therefore, there is an effect that the sound pressure difference in the observation plane can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an audio device according to an embodiment.

FIG. 2 is a diagram showing a simulation model of the present embodiment.

FIG. 3 is a diagram showing how to obtain the characteristics of each filter according to the present embodiment.

FIG. 4A is a diagram showing a response of a driver seat and a response of a passenger seat without a filter according to the present embodiment, and FIG.
FIG. 4B is a diagram illustrating a response of a driver seat, and FIG. 4B is a diagram illustrating a response of a passenger seat.

FIG. 5 is a diagram illustrating a sound pressure distribution at a frequency of an acoustic mode in a state where no filter is applied according to the present embodiment.

6A is a diagram showing a driver's seat response and a driver's seat side sound source in a state where a filter is applied according to the present embodiment; FIG.
FIG. 6B is a diagram showing a response from the driver's seat, and FIG. 6B is a diagram showing a sound source on the driver's seat side.

FIG. 7 is a diagram showing a sound pressure distribution at a frequency of an acoustic mode in a state where a filter is applied according to the present embodiment.

8 is a diagram showing a driver's seat response and a driver's seat side sound source in a state where a filter is applied at another response point of the present embodiment, FIG. 8A is a driver's seat response, and FIG. It is a figure showing a sound source of a seat side.

FIG. 9 is a diagram showing a sound pressure distribution at a frequency of an acoustic mode in a state where a filter is applied at another response point of the present embodiment.

FIG. 10 is a diagram illustrating frequency characteristics of the present embodiment;
FIG. 10A is a diagram showing frequency characteristics (target values) obtained from measurement data, and FIG. 10B is a diagram showing frequency characteristics obtained by appropriately selecting coefficients of a digital filter.

[Explanation of symbols]

1 ... automobile, 2 ... cabin, 3LF, 3RF, 3LB, 3R
B: speaker, 10: optical disk reproducing unit, 11: optical pickup, 12: spindle motor, 13: feed motor, 14: RF signal processing circuit, 15: servo control circuit,
16 demodulation DSP, 17 playback control circuit, 20 audio DSP, 21, 22, 23, 24 microphone, 25, 26, 27, 28 digital filter, 3
1, 32, 33, 34: amplifier circuit, 41: system control circuit, 42: operation key group, 43: display, 44:
AMP and A / D, 50: simulated surface,

Continuing from the front page (72) Inventor Takeshi Toi 1-13-27 Kasuga, Bunkyo-ku, Tokyo Chuo University Faculty of Science and Technology (72) Inventor Masaki Sato 1-13-27 Kasuga Bunkyo-ku, Tokyo Chuo Univ. F term (reference) 5D020 CD01 CE02 5D062 CC11 CC12 CC15 CC16

Claims (12)

[Claims] 1. A microphone is installed at an arbitrary position in a room, acoustic characteristics at the position are measured, the measured value is analyzed, and a speaker installed at a predetermined position in the room is analyzed based on the analysis value. A sound field correction method for controlling a standing wave at an arbitrary listening position by controlling a supplied audio signal to correct a frequency characteristic. 2. The sound field correction method according to claim 1, wherein the measurement position is set at a listening position. 3. The sound field correction method according to claim 1, wherein the frequency characteristics of the measurement points are corrected by controlling the frequency characteristics of the same number of speakers as the number of measurement points. . 4. The sound field correction method according to claim 3, wherein a frequency characteristic of a listening position in substantially the entire area in the room is corrected. 5. The sound field correction method according to claim 1, wherein the room is a room of a vehicle. 6. A microphone installed at an arbitrary position in a room, a measuring unit for measuring acoustic characteristics at the position, an analyzing unit for analyzing the measured value, and a speaker installed at a predetermined position in the room. A control unit that controls an audio signal supplied to the speaker based on the analysis value, and controls a standing wave at an arbitrary listening position to correct a frequency characteristic. 7. The acoustic device according to claim 6, wherein the measurement position by the measuring means is set at a listening position. 8. The acoustic device according to claim 6, wherein the control means corrects the frequency characteristics of the measurement points by controlling the frequency characteristics of the same number of speakers as the number of measurement points by the measurement means. Sound device. 9. The acoustic device according to claim 8, wherein said control means corrects a frequency characteristic of a listening position in substantially the whole area in said room. 10. The audio device according to claim 6, wherein said control means includes a calculation means and a number of F equal to or greater than the number of speakers for controlling the supplied audio signal.
An acoustic device comprising an IR digital filter. 11. The acoustic device according to claim 10, wherein said computing means computes a coefficient in said FIR digital filter. 12. The sound device according to claim 6, wherein the room is a room of a vehicle.