JP3272991B2 - How to correct sound field characteristics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for correcting sound field characteristics.

[0002]

2. Description of the Related Art Conventionally, when correcting a sound field characteristic of a listening room or the like, an audio frequency band is divided into a plurality of bands, and the level of each band in the sound field is measured with a microphone or the like, and the obtained measurement level is obtained. Was corrected by multiplying the measured amount by a fixed coefficient so that the measured value coincided with the reference level. For example, the amount of inversion of the measured value of each band, that is, the value obtained by multiplying the measured value by the correction coefficient −1 is set as the correction amount.

[0003]

However, when correcting an environment in which the characteristics of an arbitrary frequency band, such as the sound field characteristics, are strongly affected by the characteristics of other frequency bands, the above-described correction is required. Even if the correction is performed only once, the target value may not be easily reached, or the amount of correction may be extremely large in the middle of the correction, which may place a burden on the speaker.

An object of the present invention is to provide a sound field characteristic correction method which solves the above-mentioned conventional problems.

[0005]

According to the sound field characteristic correcting method of the present invention, an audio frequency band is divided into a plurality of bands and the sound pressure level of each band in the sound field is measured. And a correction method for a sound field characteristic that provides a correction amount obtained by multiplying a correction coefficient so that the obtained measurement level matches a reference level, wherein the correction amount is a relative value between the measurement result before correction and the measurement result after correction. A characteristic change amount is constantly monitored, and the correction coefficient is varied according to a ratio between the correction amount and the change amount.

According to the sound field characteristic correcting method of the present invention, the audio frequency band is divided into a plurality of bands, and the sound pressure level of each band in the sound field is measured. A method for correcting a sound field characteristic that provides a correction amount obtained by multiplying a correction coefficient so that a measured level matches a reference level, comprising the steps of: a) dividing an audio frequency band into a plurality of bands and sound pressure of each band in the sound field; Measuring the level; b) providing a correction amount (X) obtained by multiplying the measured value of each band obtained in step a) by a correction coefficient; and c) each of the corrected sound fields in step b). Measuring the sound pressure level of the band; d) calculating the absolute value (Y) of the relative change between the measurement result obtained in step a) and the measurement result obtained in step c); e. ) In the band with a large amount of change calculated in step d), a large correction coefficient K1 of 1 or less, a small correction coefficient K2 of 1 or less in a band of small change, and a correction coefficient 0 for a band of no change. Providing a correction amount multiplied to the measurement result in step c).

According to a third aspect of the present invention, there is provided a sound field characteristic correcting method according to the second aspect, wherein the correction amount X after the processing in step e) is further reduced. For a band in which the change amount Y of the corrected measurement result becomes Y ≠ 1 despite being zero, a correction amount obtained by multiplying the corrected measurement result by a smaller correction coefficient K3 of 1 or less. .

According to a fourth aspect of the present invention, there is provided a sound field characteristic correcting method according to the third aspect, wherein K1 = −0.7, K2 = K1 ×
(| Y / X |), K3 = −0.3.

[0009]

FIG. 1 is a schematic block diagram showing one embodiment of a sound field measuring device for implementing a sound field characteristic correcting method according to the present invention. 1 is a signal generator, 2 is a preamplifier,
Reference numeral 3 denotes a sound field corrector, 4 denotes a changeover switch, 5 denotes a power amplifier, 6 denotes a speaker, 7 denotes a microphone, and 8 denotes a sound field measuring device.

A signal generator 1 divides an audio frequency band signal into several bands and outputs the divided signals. The output signal is amplified by a preamplifier 2 and a terminal a of a changeover switch 4 is output.
The power is amplified by the power amplifier 5 via the power amplifier 5 and supplied to the speaker 6. The sound emitted from the speaker 6 is collected by the microphone 7 and supplied to the sound field measuring device 8.

The sound field measuring device 8 compares the level of the sound picked up by the microphone 7 with the reference level for each band of the signal output from the signal generator 1, and if they match, 0 dB;
If they do not match, for example, the measured data of the sound field is recorded in decibels, such as +3 dB when exceeding the reference level and -2 dB when below. Next, the changeover switch 4 is switched to the terminal b side.
A correction coefficient determined according to the measurement result obtained by the sound field measuring device 8 is multiplied by the signal level of each band output from the signal generator 1 and output. The level is adjusted so that the level matches the reference level over all bands, and the sound field characteristics are corrected.

Therefore, in the present invention, by monitoring the amount of change with respect to the amount of correction and varying the correction coefficient for each band, the final amount of correction can be made more flexible and without burdening the speaker. To be able to get.

Next, as a practical example of the sound field characteristic correcting method of the present invention, a sound field having the following sound field characteristics will be described.

Step 1. It is assumed that the results obtained by measuring the sound field characteristics of a certain sound field in FIG. 1 are as follows. Here, the sound field characteristics are measured by dividing the audio frequency band into five bands A to E in order from a low frequency to a high frequency band, and the obtained measurement data is expressed in decibels (dB) as a relative value to a reference level. It represents.

Step 2. Next, a correction will be considered in which the values in the sound field corrector 3 are all set to 0. Therefore, similarly to the conventional correction method, the amount of inversion of the measured value of each band, that is, the value obtained by multiplying the measured value by the correction coefficient K0 = −1 is given as the correction amount. The correction amount in that case is as follows.

Step 3. The following is an example of a measurement result obtained by performing measurement again with this correction.

Step 4. Next, when the relative change (|-|) between the first measurement result and the measurement result after the first correction in the step is calculated, the following value is obtained. Here, assuming that the absolute value of the correction amount is X and the change amount of Y is Y, bands A, C and E are Y / X ≧ 1, and band B is Y
/ X <1, Y / X = 0 for band D. In other words, bands A, C, and E are bands for which correction is effective because the amount of change is large relative to the amount of correction, band B is a band that has a slightly small amount of change but changes temporarily, and band D is a band that does not change even after correction. It can be said.

Step 5. Therefore, when performing the second correction work on the bands B to E that did not become ± 0,
Bands A, C, E that change well as the second correction amount
, A correction coefficient K1 of 1 or less, a correction coefficient K2 of 1 or less for a slightly changing band B, and a correction coefficient of 0 for a band D that does not change at all. Is given to each band. For example, as the correction amount at the time of the second correction work,
, The correction coefficient K of 1 or less for bands A, C, and E
For example, multiplying by -0.7 as 1 and applying a correction coefficient K2 of a smaller value to band B, for example, K2 = K1 × (Y
/ X) and multiply by K2 = -0.5.

Step 6. Hereinafter, the same correction operation is repeated until the measurement result converges to ± 0 for bands other than the band to which the correction coefficient 0 is not changed at all.

As described above, in steps 1 to 6, the correction amount when the correction operation is repeated for the band that did not become ± 0 based on the measurement result, and the correction coefficient larger than 1 is set for the band that changes well. By giving a small correction coefficient of 1 or less to a band that slightly changes, and giving a correction coefficient 0 to a band D that does not change at all, and giving a correction coefficient corresponding to a relative change amount to the correction amount to each band, A complicated sound field correction can be performed without putting a burden on the speaker.

In the course of the correction operation in steps 1 to 6, if there is a band in which the change amount Y of the measurement result after correction becomes Y ≠ 1 even though the correction amount X becomes zero. Gives a correction amount obtained by multiplying the measurement result after correction by a smaller correction coefficient K3 (for example, K3 = −0.3) of 1 or less as the correction amount of the band (step 7). The measurement results of all bands converge to ± 0.

As described above, in the present invention, the amount of change with respect to the correction amount is constantly monitored, and the correction coefficient is varied for each band, so that the final correction can be made more flexibly without burdening the speaker. You can get the quantity. Therefore, it is effective when correcting the sound field characteristics of a sound field that is difficult to pattern.

Note that the number of correction operations may be limited according to the correction accuracy, and the correction may be completed before the measurement result converges to ± 0.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As another embodiment of the present invention, in the block diagram of FIG. 1, a configuration is adopted in which the measurement result of the sound field measuring device 8 is fed back to the sound field correcting device 3, and the operations of steps 1 to 7 are automated. You can also.

[0025]

According to the present invention, a sound field characteristic effective in correcting an environment in which the characteristics of an arbitrary frequency band such as the sound field characteristics are strongly influenced by the characteristics of other frequency bands. Is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing one embodiment of a sound field measuring device for implementing a sound field characteristic correcting method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal generator 2 Preamplifier 3 Sound field corrector 4 Changeover switch 5 Power amplifier 6 Speaker 7 Microphone 8 Sound field measuring instrument

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04R 3/04

Claims (4)

(57) [Claims] 1. An audio frequency band is divided into a plurality of bands, and a sound pressure level of each band in a sound field is measured.
In a sound field characteristic correction method for providing a correction amount obtained by multiplying a correction coefficient so that an obtained measurement level matches a reference level, the correction amount and a relative change between a measurement result before correction and a measurement result after correction. A method for correcting sound field characteristics, wherein the amount is constantly monitored and the correction coefficient is varied according to a ratio between the correction amount and the change amount. 2. dividing an audio frequency band into a plurality of bands and measuring a sound pressure level of each band in a sound field;
A method for correcting a sound field characteristic that provides a correction amount obtained by multiplying a correction coefficient so that an obtained measurement level matches a reference level, comprising the steps of: a) dividing an audio frequency band into a plurality of bands; Measuring the sound pressure level; b) providing a correction amount (X) obtained by multiplying the measured value of each band obtained in step a) by a correction coefficient; c) the sound field after the correction in step b) Measuring the sound pressure level of each band in step d), and calculating the absolute value (Y) of the relative change between the measurement result obtained in step a) and the measurement result obtained in step c). E) a larger correction coefficient K1 of 1 or less for a band with a large change amount calculated in step d), a smaller correction coefficient K2 of 1 or less for a band with a small change amount, and a correction coefficient K of 1 or less for a band with no change. Method of correcting a sound field characteristic, wherein the step of providing a correction amount obtained by multiplying the measurement result of step c), in that it consists of. 3. The method for correcting sound field characteristics according to claim 2, further comprising the step of changing the measured result Y after the correction even though the corrected amount X after the processing in step e) is zero.
A method for correcting a sound field characteristic, comprising the step of giving a correction amount obtained by multiplying a measurement result after correction by a smaller correction coefficient K3 of 1 or less for a band that has become # 1. 4. The method of claim 3, wherein K1 = −0.7, K2 = K1 × (| Y / X |),
A method of correcting sound field characteristics, wherein K3 = −0.3.