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JPH1169482

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DESCRIPTION JPH1169482
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
method of correcting sound field characteristics.
[0002]
2. Description of the Related Art Conventionally, when correcting sound field characteristics such
as a listening room, an audio frequency band is divided into a plurality of bands, and the level of
each band in the sound field is measured by a microphone or the like, and the obtained
measurement level is obtained. The measured quantity was corrected by multiplying it by a fixed
factor so that the value of the measured level would correspond to the reference level. For
example, the amount of inversion of the measured value of each band, that is, the product of the
measured value and the correction coefficient -1 is used as the amount of correction.
[0003]
However, in the case of correction of an environment where characteristics of an arbitrary
frequency band such as sound field characteristics are strongly influenced by characteristics of
other frequency bands, as described above. Even if the correction is performed only once, the
target value may not be reached easily, or the amount of correction may become excessive on the
way to put a load on the speaker.
08-05-2019
1
[0004]
An object of the present invention is to provide a correction method of sound field characteristics
which solves the above-mentioned conventional problems.
[0005]
According to a first aspect of the present invention, a method of correcting a sound field
characteristic divides an audio frequency band into a plurality of bands and measures a sound
pressure level of each band in a sound field. And a correction method of the sound field
characteristic giving a correction amount obtained by multiplying the correction level so that the
obtained measurement level matches the reference level, the correction amount and the relative
value of the measurement result before correction and the measurement result after correction It
is characterized in that the amount of change is constantly monitored, and the correction
coefficient is varied according to the ratio between the amount of correction and the amount of
change.
[0006]
In the sound field characteristic correction method according to the present invention, as
described in claim 2, 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, and the obtained measurement level
is obtained. A sound field characteristic correction method which gives a correction amount
obtained by multiplying a correction coefficient so that Rc matches a reference level, and a)
dividing an audio frequency band into a plurality of bands and measuring the sound pressure
level of each band in the sound field And b) applying a correction amount (X) obtained by
multiplying the measured value of each band obtained in step a) by a correction coefficient, and
c) sound of each band in the sound field after correction in step b) Measuring the pressure level;
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) step d) Calculated by)
Measured in step c) for a large correction factor K1 of 1 or less for a large variation, a small
correction factor K2 for 1 or less for a small variation, and a correction factor 0 for no change at
all And D. providing a correction amount multiplied by.
[0007]
In the sound field characteristic correction method according to the present invention, as
described in claim 3, in the sound field characteristic correction method according to claim 2, the
post-processing correction amount X in step e) is zero. Adding a correction amount obtained by
multiplying the correction measurement result after correction by a correction coefficient K3
smaller than 1 or less to the band where the change amount Y of the measurement result after
correction becomes Y ≠ 1 regardless of It is characterized by including.
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[0008]
According to a fourth aspect of the present invention, there is provided a method of correcting a
sound field characteristic according to the third aspect of the present invention, wherein K1 =
−0.7, K2 = K1 × (| Y / It is characterized in that X |), K3 = -0.3.
[0009]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic block
diagram showing an embodiment of a sound field measurement apparatus for carrying out a
method of correcting a sound field characteristic according to the present invention.
1 is a signal generator, 2 is a preamplifier, 3 is a sound field corrector, 4 is a changeover switch,
5 is a power amplifier, 6 is a speaker, 7 is a microphone, and 8 is a sound field measuring device.
[0010]
The signal generator 1 divides the signal of the audio frequency band into several bands and
outputs it, and the output signal is amplified by the preamplifier 2 and power-amplified by the
power amplifier 5 through the terminal a of the changeover switch 4 to obtain a speaker 6 is
supplied.
The sound emitted from the speaker 6 is collected by the microphone 7 and supplied to the
sound field measuring device 8.
[0011]
The sound field measurement device 8 compares the level of the sound collected by the
microphone 7 with the reference level for each band of the signal output from the signal
generator 1 and 0 dB if it matches, otherwise it does not For example, the measurement data of
the sound field is recorded in decibel units, such as +3 dB for above the reference level and -2 dB
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3
for below the reference level.
Next, the changeover switch 4 is switched to the terminal b side, and the correction factor
determined according to the measurement result obtained by the sound field measurement unit 8
in the sound field correction unit 3 is output from each signal generator 1 The signal level is
multiplied and output, and level adjustment is performed so that the level of the sound collected
by the microphone 7 matches the reference level over the entire band, and the sound field
characteristic is corrected.
[0012]
Therefore, in the present invention, by monitoring the amount of change with respect to the
amount of correction and changing the correction coefficient for each band, it is possible to
obtain the final amount of correction more flexibly without putting a load on the speaker. It can
be so.
[0013]
Next, a sound field having the following sound field characteristics will be described as an actual
example of the sound field characteristic correction method of the present invention.
[0014]
ステップ1.
Suppose that the result obtained by measuring the sound field characteristic of a certain sound
field in FIG. 1 is as follows.
Here, the sound field characteristic is measured by dividing the audio frequency band from the
low frequency to the high frequency band into five bands A to E in order, and the obtained
measurement data is decibel (dB) as a relative value to the reference level Is represented.
[0015]
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ステップ2.
Next, a correction is considered in which all the values in the sound field corrector 3 are made
zero.
Therefore, as in the conventional correction method, the amount of inversion of the measured
value of each band, that is, the product of the measured value and the correction coefficient K0 =
−1 is given as the amount of correction.
The correction amount in that case is as follows.
[0016]
ステップ3. An example of the measurement result measured again with this correction is
shown below.
[0017]
ステップ4. Next, the following values can be obtained by calculating the relative change
amount (| − |) of the first measurement result and the measurement result after the first
correction of the step. Here, if the absolute value of the correction amount is X, and the change
amount of X is Y, bands A, C and E have Y / X ≧ 1, band B has Y / X <1, and band D has Y / X =
It is 0. That is, bands A, C, and E are bands for which correction is effective because the amount
of change with respect to the amount of correction is large, and band B is a band for which the
amount of change is slightly small but temporarily changes; It can be said.
[0018]
ステップ5. Therefore, when performing the second correction operation for the bands B to E
which did not become ± 0, the correction coefficients K1 for the bands A, C, and E which change
well as the second correction amount are slightly larger than one. A small correction coefficient
K2 of 1 or less is given to the changing band B, and a correction coefficient 0 is given to the band
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D not changing at all, and a correction coefficient according to the ratio of the relative change
amount to the correction amount is given to each band. For example, bands A, C, and E are
multiplied by, for example, −0.7 as a correction coefficient K1 of 1 or less, and band B is a small
value of 1 or less as a correction amount at the second correction operation. For example, K2 =
K1.times. (Y / X) is defined as the correction coefficient K2 of the above, and K2 = -0.5 is
multiplied.
[0019]
ステップ6. Thereafter, the same correction operation is repeated, and the correction operation
is repeated until the measurement result converges to ± 0 for bands other than the completely
non-changing band to which the correction coefficient 0 is given.
[0020]
As described above, in steps 1 to 6, the correction amount when repeating the correction
operation for bands that did not fall within ± 0 based on the measurement results is slightly
changed, and the correction coefficient of 1 or less is slightly changed A complex correction
factor is given to each band by giving a small correction coefficient of 1 or less to the band, a
correction coefficient of 0 to the band D which does not change at all, and a correction
coefficient according to the relative change amount to the correction amount. It is possible to
perform the field correction without putting a load on the speaker.
[0021]
If there is a band in which the change amount Y of the measurement result after correction is Y
≠ 1 despite the correction amount X becoming zero during the correction work in steps 1 to 6
By giving a correction amount obtained by multiplying the measurement result after correction
by a smaller correction coefficient K3 (eg, K3 = -0.3) smaller than 1 or less as the correction
amount of the band (step 7), The measurement results converge to ± 0.
[0022]
As described above, in the present invention, the amount of change with respect to the amount of
correction is constantly monitored, and the correction coefficient is changed for each band,
thereby obtaining a final amount of correction more flexibly without burdening the speaker. be
able to.
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Therefore, it is effective when correcting the sound field characteristic of the sound field which is
hard to be patterned.
[0023]
Note that the number of correction operations can be limited according to the correction
accuracy, and the correction can be ended before the measurement result converges to ± 0.
[0024]
DESCRIPTION OF THE PREFERRED EMBODIMENTS As another embodiment of the present
invention, in the block diagram of FIG. 1, the measurement results of the sound field measuring
device 8 are configured to be fed back to the sound field correcting device 3 to automate the
operations of steps 1 to You can also
[0025]
According to the present invention, sound field characteristics that are effective in correction of
an environment where characteristics of an arbitrary frequency band such as sound field
characteristics are strongly affected by characteristics of other frequency bands. Correction
method is obtained.
[0026]
Brief description of the drawings
[0027]
1 is a schematic block diagram showing an embodiment of a sound field measurement apparatus
for implementing the method of correcting the sound field characteristics according to the
present invention.
[0028]
Explanation of sign
[0029]
1 signal generator 2 preamp 3 sound field corrector 4 changeover switch 5 power amplifier 6
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speaker 7 microphone 8 sound field measuring instrument
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