close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2010091821

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2010091821
PROBLEM TO BE SOLVED: To reproduce a speaker of a sound field support device without
avoiding occurrence of defects such as howling and coloration of sound in a sound field support
device and an audio engineer etc. actually hearing and confirming reproduced sound. It is
possible to improve the sound quality of the sound. SOLUTION: A filter coefficient series to be set
in an FIR filter forming a closed loop with a microphone and a speaker arranged in an acoustic
space is selected according to the following conditions (A) and (B), and sound field support is set
in the FIR filter Provide an apparatus. (A) When the attenuation curve of the example of the filter
coefficient and the attenuation curve of the impulse response of the acoustic space are drawn by
superimposing the peak position, on the time axis that the area occupies in the area of the former
part projecting from the latter. The first index obtained by multiplying the weight according to
the position of is approximately 450. (B) The correlation coefficient for both attenuation curves is
0.75 or more. [Selected figure] Figure 1
Sound field support device, sound field support method and program
[0001]
The present invention relates to a technology for controlling acoustic characteristics of acoustic
space.
[0002]
There is a sound field support system based on an existing acoustic environment in an acoustic
space, enhancing and correcting reflected sound characteristics including reverberation effects
15-04-2019
1
and early reflections in the acoustic space to control the acoustic characteristics.
This sound field support system is configured of a microphone and a speaker fixed to a ceiling or
a side wall of an acoustic space, and a sound field support device connected to them. The sound
field support apparatus of this kind of sound field support system is provided with a FIR (Finite
Impulse Response) filter for applying a reverberation effect of a desired acoustic space to the
collected sound signal when the collected sound signal is input from the microphone. The
reverberation effect in the acoustic space is enhanced by repeating the process of convoluting
the filter coefficient series, emitting the resulting signal from the speaker and returning part of
the emitted sound to the microphone. Depending on the setting of the filter coefficient sequence
used for the FIR filter, it is possible to create a reverberation effect as if playing in a large
acoustic space such as a concert hall while being a narrow acoustic space. By the way, in this
type of sound field support system, as shown in FIG. 9, sound circulates in a closed loop of sound
space → microphone → sound field support device → speaker → sound space. And, if a sharp
peak appears in the amplitude characteristic of the transfer function (frequency response) of this
closed loop, hearing problems such as coloration may be caused. For example, Patent Document
1 is given as a document disclosing a mechanism for suppressing the occurrence of a sharp peak
in the amplitude characteristic of the transfer characteristic (frequency response) of a closed loop
including such an acoustic space. The sound field support device disclosed in the document
measures an open loop transfer function, which is a transfer function of the acoustic space itself,
in a state before the sound is fed back via the sound field support device. Find the inverse
characteristic of the transfer function. Then, the impulse response of this inverse characteristic is
sampled to obtain a filter coefficient sequence used for the FIR filter. Unexamined-JapanesePatent No. 07-240993 gazette
[0003]
However, as to whether or not a truly appropriate filter coefficient sequence is set, the user of
the sound field support apparatus (for example, an acoustic engineer or the like) may actually
have a hearing problem with the reproduced sound of the speaker. The problem is that you need
to listen to This is because, when a pulse-like sound is input, depending on the setting contents of
the filer coefficient sequence, an unnatural sound separated from the para sound can be heard
due to the characteristic that the FIR tap separates in the sound reproduced from the speaker
There is a case. Also, depending on the amplitude of the taps and the density of the taps, a
problem may occur in that the sound reproduced from the speaker may sound like a jerky
distorted sound. The present invention has been made in view of the above problems, and in the
sound field support system, not only the occurrence of problems such as howling and coloration
of sound but also the sound engineer etc. actually listens to the reproduced sound. It is an object
15-04-2019
2
of the present invention to provide a technology that makes it possible to improve the sound
quality of the playback sound of a speaker without making sure.
[0004]
In order to solve the above-mentioned subject, the present invention acquires the 1st data
showing the decay curve of the impulse response of acoustic space, and collects the sound
outputted from the speaker arranged in the acoustic space, and the speaker Each of the plurality
of filter coefficient sequences is selected from an FIR library in which a plurality of filter
coefficient sequences respectively stored in an FIR filter connected to a sounding microphone to
form a closed loop are stored, and the filter coefficient sequences are selected. Means for
acquiring second data representing an attenuation curve, and for each of the second data, an
attenuation curve represented by the second data and an attenuation curve represented by the
first data When the position is drawn in an overlapping manner, the portion of the portion of the
former decaying curve which protrudes from the latter decay curve is to the extent of its
protrusion A first index obtained by multiplying a weight according to the position on the time
axis, and a second index indicating the similarity with the attenuation curve represented by the
first data; In the index calculation means calculated from the second data, and in the plurality of
types of filter coefficient strings, the first index is a value near a predetermined first threshold
value, and the second index Sound field assisting apparatus characterized in that it comprises:
filter coefficient string setting means for selecting in the FIR filter the one having the degree of
similarity shown in the above at least a predetermined second threshold value and setting it in
the FIR filter; According to the present invention, there is provided a sound field support method
characterized by sequentially executing the processing to be performed, and a program that
causes a computer device to function as the above means.
[0005]
According to such a sound field support device, a sound field support method, and a program, a
plurality of filter coefficient strings stored in the FIR library can be stored in an FIR filter that
forms a closed loop with a microphone and a speaker disposed in the acoustic space. Among
them, one satisfying both of the following conditions (A) and (B) is set.
Condition (A) A portion of the former attenuation curve that protrudes from the latter
attenuation curve when the attenuation curve of the impulse response of the filter coefficient
series and the attenuation curve of the impulse response of the acoustic space are drawn by
superimposing peak positions. The first index obtained by multiplying the degree of the
protrusion in each of the points according to the position on the time axis occupied by the part is
15-04-2019
3
a value near the predetermined first threshold. Condition (B) The similarity between both
attenuation curves is equal to or greater than a predetermined second threshold. Here, it is
conceivable to use various ones of the first and second indicators, and what values are suitable as
the first and second threshold values according to the types of the indicators. Is determined.
[0006]
For example, let the attenuation curve of the impulse response for the acoustic space drawn by
superimposing each peak position be eo (t) IR and the attenuation curve of the same filter
coefficient series be eo (t) FIR according to the following equation 1 When the calculated value X
is used as the first index, a value of 450 or its vicinity may be used as the first threshold.
However, the Σ operation of equation 1 is executed only at time t satisfying equation 2 below,
and tmax in equation 1 makes the time and the amplitude of the peak position of attenuation
curve eo (t) FIR substantially zero. And the time difference between
[0007]
Here, the reason why the value of 450 or its vicinity is used as the first threshold value to be
compared with the first index (hereinafter referred to as the first index X) calculated according to
Equation 1 is as follows. According to experiments conducted by the applicant, as the first index
X calculated according to Equations 1 and 2 becomes larger than 450, unpleasant distortion in
the reproduced sound of the speaker (hereinafter referred to as “jali When the first index X falls
far below 450, the reflected sound or reverberation sound imparted by the filtering process by
the FIR filter is buried in the impulse response of the acoustic space, and the FIR filtering process
is performed. It turned out that you can not feel the effect of Therefore, in the embodiment in
which the first index X is calculated according to Equation 1 and Equation 2, it is desirable to use
a value of 450 or its vicinity as a value to be compared with the first index X.
[0008]
On the other hand, a correlation coefficient is mentioned as an example of a parameter | index
showing the similarity of two curves. For example, in the aspect using, as the second index, the
correlation coefficient xyxy calculated for the attenuation curve of the filter coefficient example
drawn by superimposing each peak position and the attenuation curve of the impulse response
of the acoustic space 1 A value of 0.75 or more may be used as the second threshold value to be
15-04-2019
4
compared with the second index in the filter coefficient string setting means. Here, the
correlation coefficient xy xy is a value calculated according to the following Equation 3 and
Equation 4 with respect to the attenuation curve eo (t) IR of the impulse response of the acoustic
space and the attenuation curve eo (t) FIR of the filter coefficient sequence According to
experiments conducted by the present applicant, when the value of the correlation coefficient xy
xy is 0.75 or more, the characteristic that the FIR tap separates in the reproduced sound of the
speaker causes an unnatural feeling separated from the parasol It turned out that the
suppression of (hereinafter referred to as "feeling of feeling") is remarkable.
[0009]
The best mode for carrying out the present invention will be described below with reference to
the drawings. (A: First Embodiment) FIG. 1 is a diagram showing an entire configuration of a
sound field support system including a sound field support device 40 according to an
embodiment of the present invention. The sound field support system controls acoustic
characteristics in the acoustic space 1. The control of the acoustic characteristics in the present
embodiment means control of the reflected sound characteristics including the characteristics of
the level of the initial reflected sound, the time structure, the arrival direction and the like, and
the reverberation characteristics. The sound field support system includes microphones 10-k (k =
1 to 8), speakers 20-m (m = 1, 2... M), a microphone amplifier unit 31, a power amplifier unit 32,
and a sound field support device 40. Have. The microphones 10-k (k = 1 to 8) and the speakers
20-m (m = 1, 2... M) are fixed to the side wall or ceiling of the acoustic space 1 with a space.
[0010]
In the sound field support device 40, sounds generated by a musical instrument or the like in the
sound space 1 are microphones 10-k (k = 1 to 8), the sound field support device 40, and
speakers 20-m (m = 1, 2) ... M) create a state of returning to the acoustic space 1 (referred to as
“acoustic feedback state”), and when the sound passes through the sound field support device
40, the sound relating to the reverberation of the acoustic space 1 and the initial reflection sound
Signal processing is performed to approximate the acoustic characteristics of another acoustic
space (referred to as “target acoustic space”) whose characteristics are to be targeted.
[0011]
FIG. 2 is a diagram showing the configuration of the sound field support device 40. As shown in
FIG.
15-04-2019
5
In this sound field support device 40, an 8-channel analog signal input from the microphone 10k (k = 1 to 8) which has collected the sound through the microphone amplifier unit 31 has an A /
D converter (not shown). After being converted to a digital format and passing through a mixer
51 and an EMR (Electronic Microphone Rotator) 52, the signal is input to an FIR (Finite impulse
response) filter 53-i (i = 1 to 4) as a four-system sound pickup signal. Be done. Here, the EMR 52
plays a role of flattening the frequency characteristic of the system by electrically switching the
connection between the four systems of signals input to the EMR 52 and the four systems of
signals output from the EMR 52 momentarily. Play.
[0012]
The FIR filter 53-i (i = 1 to 4) is a signal obtained by delaying the collected signal input from the
EMR 52 by the delay time tj (j = 1, 2... G) (“delayed audio signal sj (j = 1 , 2... G) to generate filter
coefficient values h j (j = 1, 2... G) corresponding to each of these delay times t j (j = 1, 2. j = 1, 2 ...
g), multiply each of the multiplication results, and perform the product-sum operation, and
output the result of the product-sum operation as a reverberated signal (referred to as
"reverberation sound signal") Do.
[0013]
A reverberation pattern is set to each of the FIR filters 53-i (i = 1 to 4).
The reverberation pattern is each filter coefficient value h j (j = 1, 2... G) corresponding to the
impulse response (time response) of the target acoustic space and the delay time t j (j = 1, 2. Let
htj (j = 1, 2... g), and these filter coefficients htj (j = 1, 2... g) be arranged in order of time axis.
When the impulse response (time response) at the filter coefficient htj (j = 1, 2... G) is subjected to
Fourier transform, the frequency response of the target acoustic space is obtained. Then, the
frequency response obtained by this Fourier transformation includes an amplitude characteristic
and a phase characteristic in the target acoustic space. 3A and 3B show filter coefficient values hj
(j = 1, 2... G) forming filter coefficients htj (j = 1, 2... G) of reverberation patterns and delay times
tj (j = 1, j Fig. 6 is a diagram showing an example of 2 ... g). As shown in FIG. 3 (A) and FIG. 3 (B),
reverberation patterns set for each of FIR filters 52-i (i = 1 to 4) are, for example, as shown in
FIG. 3 (A). There are various conceivable ones such as one that attenuates rapidly with the
passage of time, and one that attenuates relatively slowly as shown in FIG. 3 (B).
15-04-2019
6
[0014]
In FIG. 2, the reverberation sound signal output from the FIR filter 53-i (i = 1 to 4) is equalized by
the PEQ (Parametric Equalizer) 54-i (i = 1 to 4) and the compressor 55-i (i = 1). After passing
through dynamic range compression according to 4), the signal is input to the level / delay
matrix 58 via the switch 56-i (i = 1 to 4) and the adders 57-i (i = 1 to 4). The switch 56-i (i = 1 to
4) plays the role of switching on and off of the acoustic feedback state. The adders 57-i (i = 1 to
4) play a role of supplying the output signal to the level delay matrix 58 when the signal is
output from the noise generator 64. Although the details will be described later, the output signal
of the noise generator 64 is used when measuring the impulse response of the acoustic space 1.
[0015]
Level / delay matrix 58 is provided with M channel output signal lines (not shown) connected to
each of four input signal lines (not shown) connected to adders 57-i (i = 1 to 4) and power
amplifier unit 32. And a variable resistor for gain adjustment (not shown) and a delay element
(not shown) at each of the crossing positions. The four reverberation sound signals input to this
level / delay matrix 58 are subjected to gain adjustment and phase adjustment at the intersection
of each input signal line and the output signal line of each channel 1 to M, and M channels
Divided into Then, each of the divided M-channel reverberation sound signals is converted to an
analog signal by a D / A converter (not shown), and the converted analog signal is amplified by
the power amplifier unit 32 and then the speaker 20-m It is output to (m = 1, 2... M).
[0016]
The CPU 61 is a control center of the sound field support device 40, and executes the control
program stored in the ROM 63 while using the RAM 62 as a work area. The ROM 63 stores an
FIR library (not shown) storing a plurality of reverberation patterns, and the CPU 61 operating
according to the control program selects an acoustic space from among the reverberation
patterns stored in the FIR library. A process (hereinafter referred to as a filter coefficient
sequence optimization process) of selecting one corresponding to the attenuation characteristic
of the impulse response 1 and setting it in each of the FIR filters 53-i is executed. In the present
embodiment, the FIR library is stored in advance in the ROM 63. However, for example, the FIR
library is stored in an external memory such as a USB memory, and the external memory is
stored in the sound field support device via a USB interface or the like. The CPU 61 may be
connected to 40 and read out the reverberation pattern from the FIR library stored in the
15-04-2019
7
external memory. The operation unit 65 in FIG. 2 is an input device provided with a plurality of
operators, and is for causing the user to perform various input operations such as input of an
execution start instruction of the program. Hereinafter, the filter coefficient sequence
optimization process, which is a feature of the present embodiment, will be described in detail.
[0017]
FIG. 4 is a diagram for explaining the flow of the filter coefficient sequence optimization process.
This filter coefficient sequence optimization process is roughly divided into three steps. The first
step is a process of acquiring data representing the attenuation curve of the filter coefficient
sequence for each of the plurality of reverberation patterns stored in the FIR library and the
attenuation curve of the impulse response of the acoustic space 1 (FIG. 4: This is the first
attenuation curve data acquisition process S01a and the second attenuation curve data
acquisition process S01b). Either of the first attenuation curve data acquisition processing S01a
and the second attenuation curve data acquisition processing S01b may be executed first, or both
may be executed in parallel. The second step is a process of calculating data as an index for
selecting a reverberation pattern to be set to each of the FIR filters 53-i (i = 1 to 4) from the data
representing the respective attenuation curves (FIG. 4 The first index calculation process S02a
and the second index calculation process S02b). Either of the first index calculation process S02a
and the second index calculation process S02b may be executed first, or both may be executed in
parallel. Then, in the third step, for each of the FIR filters 53-i (i = 1 to 4), a filter coefficient
sequence (reverberation pattern) is selected based on the index calculated in the second step, and
the reverberation pattern thereof Filter coefficient string setting processing S03 for setting.
[0018]
The first attenuation curve data acquisition process S01a of FIG. 4 is a process of acquiring first
attenuation curve data representing the attenuation curve e (t) IR of the impulse response of the
acoustic space 1. More specifically, the CPU 61 first acquires data indicating the waveform of the
impulse response of the acoustic space 1 in the following manner. First, the CPU 61 switches the
switch 56-i (i = 1 to 4) to the off state, and the FIR filter 53-i (i = 1 to 4) is input to the inside of
the FIR filter 53-i. Switch to the output state without passing through ("bypass through state").
Next, the CPU 61 causes the noise generator 64 to generate a signal for impulse response
measurement (for example, a pink noise signal or the like) for a predetermined time (for example,
2 seconds). Thus, the signal output from the noise generator 64 is supplied to the CPU 61, and is
supplied to the speaker 20 via the adder 57-i (i = 1 to 4), the level delay matrix 58 and the power
amplifier unit 32. It is emitted as a test sound to the acoustic space 1 from −m (m = 1 to M).
15-04-2019
8
Then, the response sound of the test sound in the acoustic space 1 is collected by the
microphone 10-k (k = 1 to 8), and the collected signal is input to the CPU 61 via the microphone
amplifier unit 31, the mixer 51, and the EMR 52. . The CPU 61 performs the operation shown in
the following equation 5 on the sampling data g (s) representing the collected sound signal, to
thereby obtain first attenuation curve data representing the attenuation curve e (t) IR of the
impulse response of the acoustic space 1 To get In the present embodiment, the calculation
shown in the equation 5 is performed with τ = 25 milliseconds, but what value to use for this τ
may be determined by performing an experiment as appropriate.
[0019]
The second attenuation curve data acquisition process S01b of FIG. 4 acquires second
attenuation curve data representing the attenuation curve e (t) FIR of the filter coefficient
sequence in each of a plurality of reverberation patterns stored in the FIR library. Processing.
More specifically, the CPU 61 performs the operation shown in the above equation 5 (more
specifically, in the equation 5) for the combination of the filter coefficient value and the delay
time in each of a plurality of reverberation patterns stored in the FIR library. The second
attenuation curve data representing the attenuation curve e (t) FIR of the above-mentioned
impulse response is calculated by performing the operation of replacing the integration with the
sum for the delay time tj and replacing g (s) with the filter coefficient value htj). get. The first and
second attenuation curve data acquired as described above (in FIG. 4, these data are denoted as e
(t) IR and e (t) FIR) are subjected to the first index calculation processing S02a and the first index
calculation processing S02a This is input data of the second index calculation process S02b.
[0020]
The first index calculation process S02a of FIG. 4 is a process of calculating an index related to
the jaggedness of the speaker reproduction sound from the first and second attenuation curve
data. It is conceivable to use various indexes as indicators indicating such jaggedness, but in the
present embodiment, values obtained by performing the operation shown in the following
equation 7 on the time t satisfying the equation 6 below X is used as the first index. In Equations
(6) and (7), each of eo (t) IR and eo (t) FIR is the attenuation curve e (t) IR of the impulse
response of acoustic space 1 and the attenuation curve e (t) FIR of the filter coefficient example.
It is an attenuation curve obtained by giving an offset in the time axis direction so that peak
positions overlap each other. For example, the attenuation curve e (t) IR of the impulse response
of the acoustic space 1 is the waveform shown in FIG. 5A, and the attenuation curve e (t) FIR of
the filter coefficient series is the waveform shown in FIG. In this case, as shown in FIG. 5C, the
15-04-2019
9
CPU 61 applies an offset in the time axis direction to ti ′ = ti + 2 (i = 0, 1, 2...) For e (t) IR,
thereby providing an attenuation curve eo ( t) Acquire IR, and for e (t) FIR, obtain an attenuation
curve eo (t) FIR by applying an offset in the time axis direction with ti ′ = ti + 4 (i = 0, 1, 2...).
Further, for the attenuation curve eo (t) FIR obtained as described above, the CPU 61 calculates a
time difference tmax (see FIG. 5C) between the time of the peak position and the time when the
amplitude becomes substantially zero. . This tmax is used when performing the operation shown
in equation 7.
[0021]
The X calculated according to the equation 7 is the portion of the attenuation curve eo (t) FIR of
the filter coefficient series projecting from the attenuation curve eo (t) IR of the impulse response
of the acoustic space 1 (indicated by hatching in FIG. 6 It is a value obtained by multiplying the
area of the part) by the weight (t / tmax in the equation 7) according to the position of each part
on the time axis (ie time t). The reason why the value X obtained by the calculation shown in the
above equation 7 is used as an index for evaluating the sense of jerkiness is that the larger the
area of the projecting portion and the closer this portion is to tmax It is because the experimental
result that a feeling of jizziness in playback sound becomes strong was obtained. In the present
embodiment, the value X calculated according to the equation 7 is used as an index indicating the
jaggedness of the speaker reproduction sound, but a value X ′ obtained by the equation 8 below
may be used. The point is that when the attenuation curve of the filter coefficient series and the
attenuation curve of the impulse response of the acoustic space 1 are drawn by superimposing
the peak positions, that in each of the portions of the former attenuation curve projecting from
the latter attenuation curve It may be a value obtained by multiplying the degree of protrusion by
a weight according to the position on the time axis occupied by those parts. In the equation 8, m
and n are arbitrary natural numbers (however, n ≠ 1 when m = 1 and m ≠ 1 when n = 1)
[0022]
The second index calculation process S02b in FIG. 4 is a process of calculating an index related to
the paraphrasing of the speaker reproduction sound from the first and second attenuation curve
data. Although it is conceivable to use various indexes as indicators to indicate such sense of
paraplegia, in the present embodiment, the value xyxy obtained by the calculation shown in the
following equation 9 is used. In this equation 9, σx is the standard deviation for eo (t) FIR, and
σy is the standard deviation for eo (t) IR. Further, σxy of equation 9 is a value calculated
according to the following equation 10. <eo (t) FIR> of equation 10 is an average value of eo (t)
FIR, and <eo (t) IR> is an eo (T) Average value of IR. That is, the value xy xy calculated according
15-04-2019
10
to the equation 9 is a correlation coefficient between the attenuation curve eo (t) FIR and the
attenuation curve eo (t) IR, and represents the similarity between both attenuation curves.
[0023]
Here, the reason for using the value indicating the similarity between the waveform of the
attenuation curve eo (t) FIR and the waveform of the attenuation curve eo (t) IR as an index for
selecting the filter coefficient sequence is as follows. FIG. 7 is a graph depicting the attenuation
curve eo (t) IR and the attenuation curve eo (t) FIR of a certain filter coefficient sequence, and the
waveforms of the two are largely different in the portion surrounded by the dotted line in FIG.
There is. It was found by experiments conducted by the present applicant that the difference of
this waveform is perceived as the above-mentioned sense of paraplegia. That is, in order to
suppress a sense of parasolation in the speaker reproduction sound, a filter coefficient series
having an attenuation curve having a high degree of similarity with the attenuation curve of the
impulse response of the acoustic space 1 is FIR filter 53-i (i = 1 to 4) It may be set to each of.
This is the reason why the value indicating the similarity between the waveform of the
attenuation curve eo (t) FIR and the waveform of the attenuation curve eo (t) IR is used as an
index for selecting the filter coefficient string. In the present embodiment, the correlation
coefficient is used as an index indicating the similarity between the waveform of the attenuation
curve eo (t) FIR and the waveform of the attenuation curve eo (t) IR, but other indexes may be
used as a matter of course. As an example of such an index, for example, the distance between
these two points (for example, Euclidean distance) in the case where the attenuation curve eo (t)
FIR and the attenuation curve eo (t) IR are represented as coordinate points in a
multidimensional space. It is conceivable to use both attenuation curves as the distance between
these two points is shorter.
[0024]
The filter coefficient string setting process S03 of FIG. 4 is the first index (X in this embodiment)
calculated by the first index calculation process S02a and the second index calculated by the
second index calculation process S02b. (In the present embodiment, based on xyxy), from among
a plurality of types of reverberation patterns stored in the FIR library, one to be set for each of
the FIR filters 53-i (i = 1 to 4) is selected , It is the process which performs the setting. More
specifically, in the filter coefficient string setting process S03, the CPU 61 sets, in advance, a first
index to be calculated for the attenuation curve of the filter coefficient string among a plurality of
types of reverberation patterns stored in the FIR library. The value is selected and set in the
vicinity of the first threshold, and the similarity indicated by the second index is equal to or
15-04-2019
11
greater than a predetermined second threshold.
[0025]
Here, with regard to the first threshold for performing the evaluation on the first index and the
second threshold for performing the evaluation on the second index, what are the first and
second indexes described above? It is necessary to set appropriately according to whether to use
a kind of thing. However, it should be noted that the first threshold is not too small. If the first
threshold is made too small, for example, in the filter coefficient sequence setting process S03, a
filter coefficient sequence in which most of the attenuation curve eo (t) FIR falls below the
attenuation curve eo (t) IR (ie, FIR filter A filter coefficient sequence that causes the frequency
characteristics to be buried in the frequency characteristics of the acoustic space is set in the FIR
filter 53-i, and the FIR filter 53-i may not perform its original function such as generation of
reverberation and reflected sound. It is because there is. For example, in the case of using X
calculated according to the above equation 7 as the first index, it is preferable to use a value of
450 or its vicinity as the first threshold, and to use the value 9 above as the second index.
Therefore, in the case where the calculated ρ xy is used, it has been found from experiments
conducted by the applicant that it is preferable to use a value of 0.75 or more as the second
threshold value.
[0026]
Now, various modes can be considered as an aspect of determining the filter coefficient sequence
to be set to the FIR filter 53-i based on the first and second indexes, but an example thereof is as
follows. First, in the filter coefficient series in which the value of the second indicator is equal to
or greater than a predetermined second threshold, the one having the value of the first indicator
closest to the predetermined first threshold is FIR Similarity expressed by a second index among
the filter coefficient sequence in which the mode of setting to the filter 53-i and the value of the
first index fall within a predetermined range centered on a predetermined first threshold Is the
aspect which sets the largest thing to FIR filter 53-i. According to these aspects, it is possible to
automatically set the filter coefficient sequence suitable for the acoustic characteristics of the
acoustic space 1 in the FIR filter 53-i without the user performing a special operation.
[0027]
15-04-2019
12
The second aspect is a predetermined range in which the value of the first index is centered on
the first threshold (for example, in the case where the first threshold is 450, a range of ± 50
around this value, etc. An identifier (for example, a plurality of types stored in the FIR library) for
uniquely identifying a filter coefficient sequence belonging to a filter coefficient sequence
belonging to the above and the second index indicates that the degree of similarity is equal to or
higher than the second threshold Serial numbers assigned to each of the reverberation patterns,
the first and second indices calculated for the filter coefficient sequence, and t.sub.max in the
manner shown in FIG. In this mode, the user can select a filter coefficient sequence to be set in
each of the FIR filters 53-i (i = 1 to 4) by operating the operation unit 65. According to this
aspect, for example, it is possible to flexibly select a filter coefficient sequence to be set in the FIR
filter 53-i, such as selecting one having the largest value of tmax (that is, the longest
reverberation time). Even if the filter coefficient string is selected based on the value of tmax as
described above, any of the filter coefficient strings displayed in the list satisfies the
predetermined condition with respect to the first and second indexes. Therefore, it is needless to
say that the jaggedness or parasolarity of the speaker reproduction sound is suppressed when
the filter coefficient sequence is set to the FIR filter 53-i.
[0028]
As described above, according to the present embodiment, in the sound field support system, the
sound engineer or the like reproduces each of the speakers 20-m, as well as avoiding the
occurrence of defects such as howling and coloration of sounds. It is possible to improve the
sound quality of the reproduced sound without actually hearing and confirming the sound.
[0029]
(B: Other Embodiments) Although the embodiments of the present invention have been described
above, the following embodiments can be considered.
(1) In the embodiment described above, the impulse response for the acoustic space 1 was
measured, and from the measurement result, attenuation curve data representing the attenuation
curve was calculated and acquired. However, an external memory storing data indicating the
measurement result of the impulse response of the acoustic space 1 is connected to the sound
field support device 40, and the attenuation curve data representing the attenuation curve is
calculated from the data stored in the external memory. You may. Alternatively, an external
memory storing attenuation curve data representing the attenuation curve of the impulse
response of the acoustic space 1 may be connected to the sound field support device 40, and the
attenuation curve data stored in the external memory may be read out. Similarly, data
15-04-2019
13
representing attenuation curves of each filter coefficient sequence may be calculated in advance,
and data representing pairs of filter coefficient values and delay times and the above-mentioned
attenuation curves may be used as reverberation patterns.
[0030]
(2) In the embodiment described above, the control program for causing the CPU 61 to execute
the filter coefficient string optimization process (see FIG. 4) characteristic of the present
invention is stored in advance in the ROM 63. However, for example, the program may be
distributed by writing the program in a computer apparatus readable recording medium such as
a CD-ROM (Compact Disk-Read Only Memory), or by downloading via a telecommunication line
such as the Internet. You may distribute it. These general computers are stored by storing the
program distributed as described above in a general computer device (for example, a personal
computer) and operating the control unit (CPU) of the computer device according to the
program. This is because the device can be provided with the same function as the sound field
support device 40 according to the above embodiment.
[0031]
(3) In the above-described embodiment, the filter coefficient sequence optimization process (FIG.
4) characteristic of the present invention is realized by software, but it may be realized by
hardware. Specifically, the first attenuation curve data representing the attenuation curve of the
impulse response of the acoustic space (for example, the acoustic space 1 in the above
embodiment) to be subjected to sound field control, and the attenuation curve of each filter
coefficient sequence Attenuation curve data acquisition means for acquiring second attenuation
curve data, calculation means for calculating data serving as an index for selecting a filter
coefficient string, selection of a filter coefficient string based on the index and setting to an FIR
filter Each of the filter coefficient string setting means for performing the above may be
constituted by an electronic circuit, and the respective means may be combined to constitute the
sound field support device.
[0032]
It is a figure showing an example of composition of a sound field support system containing
sound field support device 40 concerning one embodiment of the present invention. FIG. 6 is a
15-04-2019
14
diagram showing an example of the configuration of the same sound field support device 40. It is
a figure which shows an example of the reverberation pattern set to FIR filter 53-i (i = 1-4) of the
sound field assistance apparatus 40. FIG. It is a figure which shows the flow of the filter
coefficient string optimization process which CPU61 of the same sound field assistance
apparatus 40 performs. It is a figure for demonstrating the offset provision process which the
said CPU61 performs by 1st and 2nd index calculation process. It is a figure for demonstrating
the meaning of 1st parameter | index X calculated by 1st parameter | index calculation process
S02a contained in the filter coefficient row optimization process. It is a figure for demonstrating
the meaning of 2nd parameter | index (rho) xy calculated by 2nd parameter | index calculation
process S02b contained in the filter coefficient sequence optimization process. FIG. 7 is a
diagram showing an example of a UI screen for allowing a user to select a filter coefficient
sequence to be set in an FIR filter among setting candidates narrowed down based on the first
index X and the second index xyxy. It is a figure for demonstrating the operation | movement of a
sound field assistance system.
Explanation of sign
[0033]
DESCRIPTION OF SYMBOLS 1 ... Acoustic space, 10-k (k = 1-8) ... Microphone, 20-m (m = 1-M) ...
Speaker, 31 ... Microphone amplifier part, 32 ... Power amplifier part, 40 ... Sound field assistance
apparatus, 51 ... mixer, 52 ... EMR, 53-i (i = 1 to 4) ... FIR filter, 54-i (i = 1 to 4) ... PEQ, 55-i (i = 1
to 4) ... compressor, 56- i (i = 1 to 4) ... switch, 57-i (i = 1 to 4) ... adder, 58 ... level delay matrix,
61 ... CPU, 62 ... RAM, 63 ... ROM, 64 ... noise generator, 65 ... the operation unit.
15-04-2019
15
Документ
Категория
Без категории
Просмотров
0
Размер файла
31 Кб
Теги
description, jp2010091821
1/--страниц
Пожаловаться на содержимое документа