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JP2003224898

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DESCRIPTION JP2003224898
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
loudness intelligibility improvement apparatus and a loudness intelligibility improvement method
suitable for performing loudness in loudness in a reverberant environment such as a tunnel.
[0002]
2. Description of the Related Art Conventionally, as a technology for performing high definition
broadcasting using electro-acoustic equipment in an environment such as a tunnel or the like in
which reverberation or reflected sound tends to occur, for sound field control composed of an
FIR filter etc. The method of controlling the input by placing the filter of the previous stage of the
amplifier has been implemented. The coefficients of the FIR filter are calculated in advance using,
as parameters, target characteristics of the control target point which is a place where the
broadcast sound is actually heard and a transfer coefficient of a path (sound field) from the
speaker to the control target point.
[0003]
As a technology in this field, for example, the “clarity improvement method and sound field
control device” disclosed in Japanese Patent Laid-Open No. 11-262083 set target
characteristics only from a part of the initial input including direct sound. Thus, the clarity is
improved in a wide area without lengthening the filter length of the sound field control filter,
even when the target characteristic and the transfer coefficient greatly differ.
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[0004]
Also, in the "sound amplification apparatus and its clarity improvement method" disclosed in
Japanese Patent Application Laid-Open No. 2000-165984, the impulse response between the
speaker and its control target point is determined when determining the coefficients of the FIR
filter, By calculating the acoustic transfer function matrix for each frequency, the intelligibility is
improved even if the amount of operation of the sound field control filter is reduced and the
number of sound field control filters is reduced.
[0005]
However, in the sound amplification technology using the sound field control filter such as the
FIR filter described above, some change occurs in the sound field (transmission path of sound)
different from that at the time of determining the coefficient of the FIR filter. (Eg, when the traffic
of vehicles in the tunnel changes and the transfer function changes), the reverberation does not
decrease, that is, the reverberation component may not be removed. .
[0006]
Furthermore, as described in "Japanese Patent Application Laid-Open No. 11-262083" Method
for improving clarity and sound field control apparatus ", and Japanese Patent Application LaidOpen No. 2000-165984 for" sound amplification apparatus and method for improving its clarity
", FIR filter Basically, the sound amplification technology using a sound field control filter such as
that has a problem that it has an effect only on the area of the control target point.
[0007]
The present invention has been made in view of the above-described conventional problems, and
it is an object of the present invention to provide a loudness intelligibility improvement device
and a loudness intelligibility improvement method capable of realizing high fidelity loudness in a
reverberant environment The purpose is.
[0008]
SUMMARY OF THE INVENTION In order to solve the above problems, a loudness intelligibility
improvement apparatus according to the present invention is a loudness intelligibility
improvement apparatus for improving the intelligibility of loudness in a closed space.
Measurement impulse response acquiring means for acquiring a measurement impulse response
which is an impulse response output from the speaker installed in the closed space, calculation
impulse response calculating means for calculating the impulse response by calculation, and
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2
output from the speaker A processor having equalizer means capable of adjusting the output
level of the voiced sound in each frequency band, reverberation time judging means for judging
whether the reverberation time exceeds a predetermined time from the measurement impulse
response, the reverberation time Differential energy between the measured impulse response of
the frequency band above and the calculated impulse response of the frequency band Means for
calculating differential energy for each frequency band, and means for generating inverse
transfer function capable of eliminating the differential energy based on the difference energy of
each frequency band calculated by the difference energy calculating means And an analyzer for
setting an equalizer parameter satisfying the inverse transfer function created by the inverse
transfer function creating means to the equalizer means of the processor.
[0009]
Further, in the loudness intelligibility improvement apparatus according to the present invention,
the processor has a calculation impulse response normalization means for normalizing the
calculation impulse response with the maximum value of the measurement impulse response,
and the difference energy calculation means The difference energy between the measured
impulse response of each frequency band for which the reverberation time exceeds the
predetermined time and the normalized calculated impulse response of the frequency band is
calculated.
[0010]
Therefore, the volume level of the above-mentioned frequency band can be reduced without
much change of the original sound quality of the speaker with respect to the frequency band
with a long reverberation time that affects the clarity, even in an environment where
reverberation tends to occur. It is possible to realize a loud voice with high clarity.
[0011]
Further, in the loud-speaking clarity improving device according to the present invention, the
analyzer has graph creating means for creating a graph showing the difference energy calculated
by the difference energy calculating means for each frequency band.
Therefore, by referring to the created graph, it can be known in which frequency band the
reverberation / reflection component is large.
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[0012]
Also, a loudness intelligibility improvement method according to the present invention is a
loudness intelligibility improvement method for improving the intelligibility of loudness
performed in a closed space, comprising: an output from a speaker installed in the closed space
Measuring impulse response acquiring step of acquiring a measured impulse response which is
the determined impulse response, calculating impulse response calculating step of calculating
impulse response by calculation, and reverberation determining whether reverberation time
exceeds a predetermined time from the measuring impulse response A differential energy
calculating step of calculating a difference energy between a time determining step, a
measurement impulse response for each frequency band in which the reverberation time exceeds
the predetermined time, and a calculation impulse response of each frequency band; On the basis
of the difference energy of each frequency band Reverse transfer function creating step for
creating a transferable reverse transfer function, and the reverse transfer function creating step
for equalizer means capable of adjusting the output level of the sound output from the speaker
for each frequency band And an equalizer parameter setting step of setting an equalizer
parameter satisfying the inverse transfer function.
[0013]
Further, the method of improving loudness intelligibility according to the present invention
further comprises a calculation impulse normalization step of normalizing the calculation
impulse response with the maximum value of the measurement impulse response, wherein the
difference energy calculation step comprises the reverberation time The difference energy
between the measured impulse response of each frequency band over time and the normalized
calculated impulse response of each frequency band is calculated.
[0014]
Further, the method of improving loudness intelligibility according to the present invention has a
graph creating step of creating a graph showing the difference energy calculated in the
difference energy calculating step for each frequency band.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a loudness
intelligibility improvement apparatus and a loudness intelligibility improvement method
according to the present invention will be described in detail with reference to the drawings.
[0016]
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FIG. 1 is a block diagram showing an apparatus for improving speech clearness according to an
embodiment of the present invention.
The speech intelligibility improving apparatus shown in the figure is configured to include an
analyzer 1, a processor 2, a preamplifier 3, an amplifier 4, a speaker 5, a broadcasting
microphone 6, and a measuring microphone 7.
The speaker 5, the broadcast microphone 6 and the measurement microphone 7 are installed in
an internal space such as a tunnel or underground road where reverberation is likely to occur.
[0017]
Hereinafter, each component which the loud-speaking clearness improvement apparatus of this
embodiment has is demonstrated.
First, the analyzer 1 incorporates an acoustic simulation system and sends out EQ parameters
obtained by calculation necessary to improve the intelligibility from the difference between
measured data and data obtained by the simulation, and via the processor 2 Voice data collected
from the sound field (sound field formed in the path between the speaker 5 and the
measurement microphone 7), and mainly includes an analysis unit 11 and a display unit 12
There is.
The analysis unit 11 analyzes audio data sent from the processor 2 and calculates parameters
necessary for realizing the equalizer function of the processor 2.
Further, the display unit 12 displays an intermediate result of voice data analysis and the like.
A detailed description of analysis of voice data and calculation of parameters performed by the
analysis unit 11 will be made with reference to the flowchart shown in FIG.
[0018]
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Further, the processor 2 quantifies the audio signal collected from the sound field through the
measurement microphone 7 when the audio signal is broadcast and converts it into audio data,
and the volume level according to the analysis result of the analyzer 1 To form an equalizer
function for adjusting each frequency band.
Further, the preamplifier 3 pre-amplifies the broadcast audio signal.
Further, the amplifier 4 is for amplifying the audio signal output outputted from the processor 2.
The speaker 5 converts the output of the amplifier 4 into sound.
Also, the broadcast microphone 6 converts audio to be broadcast into a broadcast audio signal.
Furthermore, the measurement microphone 7 converts the sound collected from the sound field
corresponding to the speaker 5 into a sound signal.
[0019]
Hereinafter, the method of improving loudness intelligibility according to the present
embodiment will be described with reference to FIG. FIG. 2 is a flowchart illustrating a method of
improving loudness intelligibility according to an embodiment of the present invention. First, a
person who operates the analyzer 1 selects a speaker that forms a sound field for improving the
reverberation (step S1). In the present embodiment, it is assumed that the speaker 5 is selected.
Thereafter, the position of the selected speaker 5 is set (step S2). Also, by setting the sound
receiving position (the position of the measurement microphone 7), the condition of the sound
field to be measured is made to match (step S3).
[0020]
Next, the analysis unit 11 of the analyzer 1 starts analysis by generating a direct sound signal
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using the built-in sound simulator and sending it to the processor 2 (step S4). Then, the
processor 2 processes the direct sound sent from the analysis unit 11 to be broadcast via the
amplifier 4 and the speaker 5, measures the direct sound outputted from the speaker 5 with the
measurement microphone 7, and directly processes the direct sound. The impulse response of
the sound is acquired (step S5). The impulse response thus obtained is hereinafter referred to as
"measurement impulse response". The measured impulse response is sent to the analyzer 1 via
the processor 2.
[0021]
On the other hand, the processor 2 calculates the impulse response of only the direct sound sent
from the analysis unit 11 by calculation using acoustic simulation or the like (step S6). The
impulse response thus obtained is hereinafter referred to as "computed impulse response". The
calculated impulse response is normalized by the maximum value of the measured impulse
response in processor 2 and sent to analysis unit 11.
[0022]
Next, the analysis unit 11 of the analyzer 1 calculates the reverberation time from the
measurement impulse response acquired in step S5, and determines whether the reverberation
time exceeds a predetermined time (for example, 3 seconds) (step S7). . If the reverberation time
exceeds the predetermined time, the analysis unit 11 calculates the difference energy between
the measured impulse response obtained in step S5 and the calculated impulse response
obtained in step S6 in the same frequency band, The result is stacked in an internal memory (not
shown) (step S8). The difference energy means an energy component increased by reverberation
and reflection in the sound field.
[0023]
Next, it is determined whether or not the process of step S7 and step S8 has been performed for
all 1 / n bands (step S9). If all of the 1 / n band has not been performed, the processing of steps
S5 and S6 in the next 1 / n band is performed.
[0024]
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In step S10, the analysis unit 11 of the analyzer 1 generates a graph indicating the differential
energy calculated in step S8 for each 1 / n band, and displays the graph on the display unit 12.
An example of the graph generated in the step is shown in FIG. In the graph, the X axis is the
frequency of the direct sound in the 1 / n band, and the Y axis is the orthogonal coordinates with
the difference energy.
[0025]
Next, based on the graph generated in step S10, the analysis unit 11 creates an inverse transfer
function capable of erasing the differential energy shown in the graph, and an equalizer
parameter satisfying the inverse transfer function (hereinafter referred to as “ It is called "EQ
parameter". ) Is calculated (step S11). In step S7, the difference energy is calculated only for the
frequency band in which the reverberation time exceeds the predetermined time, that is, only the
frequency at which the difference energy exceeds the predetermined time and the reverberation
or reflection is eliminated by the equalizer Target frequency band.
[0026]
Next, the analysis unit 11 sends the EQ parameter calculated in step S12 to the processor 2, and
the processor 2 executes the EQ parameter as a equalizer circuit corresponding to the equalizer
means in the claims or a filter for realizing the equalizer function. The setting is made (step S12),
and the series of processing is ended.
[0027]
As described above, according to the loudness intelligibility improvement apparatus and the
loudness intelligibility improvement method of the present embodiment, the reverberation time
is measured in the 1 / n [octave] frequency band with respect to the sound field, and the
intelligibility is affected. Since the volume level of the above frequency band is reduced with little
change to the original sound quality possessed by the speaker 5 with respect to the frequency
band having a long reverberation time, the clarity is high even in an environment in which
reverberation is likely to occur. Loudspeaking can be realized.
Further, by referring to the graph showing the difference energy (the amount of energy increased
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by the reverberation and reflection in the sound field) for each frequency band, it can be known
in which frequency band the reverberation and reflection component is large.
[0028]
In this embodiment, the analysis unit 11 includes the sound simulator and sends the direct sound
to the processor 2. However, the music performance by an announcement or a CD sound source
is converted into an audio signal through the broadcasting microphone 6. This may be sent to the
processor 2 as a direct sound.
[0029]
As described above, according to the apparatus for improving loudness intelligibility and the
method for improving loudness intelligibility according to the present invention, the speaker has
an effect on the frequency band having a long reverberation time which affects the intelligibility.
Since the volume level of the above-mentioned frequency band can be reduced without
significantly changing the sound quality of the above, it is possible to realize a high definition
speech even in an environment where reverberation is likely to occur.
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