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JP2002027585

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DESCRIPTION JP2002027585
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
acoustic system for detecting noise and automatically adjusting the sound quality and volume of
the output sound according to the detected noise, and an electroacoustic transducer provided in
the acoustic system. And an acoustic device, more specifically, an acoustic system for
transmitting a detected noise through a common signal line through a common signal line, an
electrical signal for converting the detected noise into an electrical signal and an output sound,
an electroacoustic transducer provided in the acoustic system, and It relates to an acoustic
device.
[0002]
2. Description of the Related Art Conventionally, as an acoustic system for automatically
adjusting the sound quality and the volume of the sound to be output according to the detected
noise, an acoustic system as disclosed in JP-A-6-334457 is known. ing.
[0003]
Hereinafter, an example of an acoustic system for automatically adjusting the sound quality and
the volume of the sound to be output according to the conventional detected noise will be
described with reference to FIG.
[0004]
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1
In the acoustic system 900, noise at a place where the speaker 902 is used (hereinafter referred
to as ambient noise).
) Is picked up by the pickup microphone 901 and converted into a noise signal.
When ambient noise is converted into a noise signal by the sound collection microphone 901, the
converted noise signal is input into the acoustic device 910 from the noise signal input terminal
911, and is converted into an A / D converter by the analog band limiting filter 912. In order to
prevent aliasing due to 913, the frequency band of 1/2 or less of the sampling frequency of the A
/ D converter 913 is band-limited so as to be a pass band, and then input to the A / D converter
913. When the noise signal is input, the A / D converter 913 converts the input noise signal from
an analog signal into a digital signal, and inputs the signal into the noise characteristic analysis
unit 914. When the noise characteristic analysis means 914 receives the noise signal, it analyzes
the frequency characteristic level of the ambient noise from the inputted noise signal.
[0005]
Here, the sound source device 930 is an announcement, a loud sound such as BGM, or a received
sound in two-way communication (hereinafter simply referred to as a loud sound). ) Is input to
the inside of the sound device 910 from the speech sound signal input terminal 915, the input
speech sound signal is aliased by the A / D converter 917 by the analog band limiting filter 916.
In order to prevent this, the frequency band of 1/2 or less of the sampling frequency of the A / D
converter 917 is band-limited so as to be a pass band, and then input to the A / D converter 917.
When an A / D converter 917 receives an input of a loud sound signal, it converts the input loud
sound signal from an analog signal to a digital signal, and controls a loud sound characteristic
analysis unit 918 and volume and quality of the loud sound. And sound control means 920.
When the loud sound signal is inputted, the loud sound characteristic analysis means 918
analyzes the frequency characteristic level of the loud sound from the inputted loud sound signal.
[0006]
The noise characteristic analysis means 914 and the loud sound characteristic analysis means
918 respectively analyze the frequency characteristic levels of the ambient noise and the loud
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2
sound, and calculate the compensation amount calculation means 919 for the frequency
characteristic level of the analyzed ambient noise and loud sound. Enter in When the frequency
characteristic levels of the ambient noise and the loud noise are input to the compensation
amount calculation means 919 by the noise characteristic analysis means 914 and the loud voice
characteristic analysis means 918, the compensation amount calculation means 919 calculates
the input ambient noise and loud noise. Based on the frequency characteristic level, the
compensation amount for compensating the loudspeaker sound signal input from the sound
source device 930 is calculated according to the purpose of compensating for the masking of the
loudspeaker sound due to the ambient noise, etc. Input to the sound control means 920.
[0007]
When the loud sound signal and the compensation amount are inputted, the sound control
means 920 controls the volume and the sound quality of the loud sound by changing the loud
sound signal inputted according to the inputted compensation amount. When the sound control
means 920 changes the input loud sound signal, the sound change sound signal changed by the
sound control means 920 is converted by the D / A converter 921 from a digital signal to an
analog signal, and an analog band limiting filter After being band-limited by 922, the signal is
output from the loud sound signal output terminal 923 to the outside of the acoustic device 910.
When the loud sound signal is output to the outside of the acoustic device 910, it is amplified by
the power amplifier 940, then converted into a loud sound by the speaker 902, and is loudened.
[0008]
As described above, according to the conventional sound system 900, the sound output
according to the detected noise, that is, the ambient noise collected by the sound collection
microphone 901, that is, the sound quality of the loud sound amplified by the speaker 902. And
the volume was automatically adjusted.
[0009]
However, in the above-described conventional audio system 900, a cable 951 (see FIG. 13) for
connecting the sound collection microphone 901 and the audio device 910, a speaker 902 and
the audio device 910 are used. Since the cables 952 and 953 (see FIG. 13) to be connected are
separately required, for example, the audio system 900 is installed by installing the audio device
910 in the broadcast room and installing the sound collection microphone 901 and the speaker
902 in the sales floor. If the distance between the place where the sound device 910 is installed
and the place where the sound collection microphone 901 and the speaker 902 are installed is
long, as in a department store that performs in-store broadcasting using There is a problem that
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the work becomes complicated.
[0010]
Further, in the above-described conventional audio system 900, since the cable 951 and the
cables 952 and 953 are separately required, for example, the speaker is installed but the sound
collecting microphone is not installed. And an audio system that does not have a function to
automatically adjust the sound quality and volume of the loud sound to be output according to
the detected noise, and adds the sound collection microphone 901 to output according to the
detected noise When adding a sound collection microphone to an existing sound system, as in
the case of changing to an audio system 900 that automatically adjusts the sound quality and
volume of sound, the cable 951 must be newly installed to add a sound collection microphone.
There was a problem that it was impossible.
[0011]
As an acoustic system capable of solving the above-mentioned problems, as shown in FIG. 14, a
sound collecting microphone and a speaker 903 which can be used as a sound collecting
microphone are also provided. A sound system 950 is known in which the sound collecting
microphone and the combined speaker 903 can be used as a sound collecting microphone only
when there is no loud sound to be amplified from the dual purpose speaker 903.
In the sound system 950, since the sound collecting microphone dual purpose speaker 903 is
used as a sound collecting mic only when there is no loud sound amplified from the sound
collecting mic dual purpose speaker 903, the sound collecting microphone dual purpose speaker
903 collects ambient noise. A noise signal converted by sound and a loud sound signal output
from the sound device 910 are not simultaneously transmitted on the cable 954, and a cable
connecting the sound pickup microphone and the speaker 903 and the sound device 910, a
speaker It is possible to use a common cable 954 in part for the cable connecting the 902 and
the acoustic device 910.
In FIG. 14, the same components as those in FIG. 13 are denoted by the same reference numerals
as those in FIG.
[0012]
However, in the conventional sound system 950, as shown in FIG. 14, when the sound collecting
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microphone and speaker 903 and the speakers 902 other than the sound collecting microphone
and speaker 903 are connected in parallel, the sound collecting microphone When the dual use
speaker 903 is used as a sound collection microphone, there is a problem that it is impossible to
use the speaker 902 as well as the sound collection microphone also as the sound collection
microphone and the speaker 902 to amplify the loud sound.
[0013]
Therefore, according to the present invention, it is possible to connect between the sound
collecting microphone and the sound device and between the speaker and the sound device using
a common cable, and simultaneously use the sound collecting microphone and the speaker. It is
an object of the present invention to provide an acoustic system, and an electroacoustic
transducer and an acoustic device provided in the acoustic system.
[0014]
SUMMARY OF THE INVENTION In order to solve the above problems, the electroacoustic
transducer of the present invention is converted by electroacoustic transducing means for
transducing sound into an electrical signal, and the electroacoustic transducing means. And
frequency conversion means for converting a frequency band in which the electric signal is
included.
With this configuration, the electro-acoustic transducer of the present invention can change the
frequency band of the electrical signal converted from the collected sound to a frequency band
different from the frequency band of the loud sound signal output from the acoustic device to the
speaker. it can.
Therefore, the electro-acoustic transducer of the present invention is connected to an acoustic
device capable of changing an acoustic signal based on an electrical signal whose frequency band
has been changed by the electro-acoustic transducer of the present invention. It is possible to
connect between the electroacoustic transducer and the acoustic device, and between the
loudspeaker and the acoustic device using a common cable, and simultaneously use the
electroacoustic transducer of the present invention and the loudspeaker it can.
[0015]
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5
Further, the electroacoustic transducer of the present invention comprises transformation
determining means for deciding whether or not to convert the frequency band in which the
electric signal transformed by the electroacoustic transducer is included in the frequency
transforming means. The electro-acoustic conversion means can convert an electrical signal into
sound.
According to this configuration, the electro-acoustic transducer of the present invention can not
only pick up the sound but also make it possible to amplify a loud sound.
[0016]
In the electro-acoustic transducer according to the present invention, the frequency conversion
means may be an analog-to-digital conversion means for converting the electric signal from an
analog signal to a digital signal, and a digital signal converted by the analog-to-digital conversion
means And D / A conversion means for converting the electrical signal from a digital signal to an
analog signal. With this configuration, the electroacoustic transducer according to the present
invention has a simple configuration in which the frequency band of the electrical signal
converted from the collected sound is different from the frequency band of the loud sound signal
output from the acoustic device to the speaker It can be changed.
[0017]
Also, in the electro-acoustic transducer of the present invention, the frequency conversion means
comprises frequency increase means for increasing the sampling frequency of the electric signal
converted into a digital signal by the analog-to-digital conversion means. It is a feature.
According to this configuration, the electroacoustic transducer of the present invention can easily
remove, by the digital band-limiting filter, an electrical signal included in an unnecessary
frequency band among the electrical signals converted into digital signals by the analog-to-digital
conversion means. it can.
[0018]
In the electro-acoustic transducer according to the present invention, the frequency increasing
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means increases the sampling frequency of the electric signal converted into a digital signal by
the analog-to-digital converting means to an integral multiple. It is. According to this
configuration, the sampling frequency of the electrical signal converted into the digital signal can
be increased only by performing simple processing on the electrical signal converted into the
digital signal.
[0019]
Also, according to the sound device of the present invention, an electric signal input means for
receiving an electric signal converted from sound, an electric signal output means for outputting
an electric signal converted to sound, and the electric signal output means Electrical signal
generating means for generating the electrical signal to be output from the electrical signal
generating means, wherein the electrical signal generating means outputs the electrical signal
output from the electrical signal output means among the electrical signals input from the
electrical signal input means The electric signal output from the electric signal output means is
generated according to the electric signal contained in a frequency band other than the
frequency band in which the signal is contained. According to this configuration, the acoustic
device of the present invention generates the electrical signal output from the electrical signal
output means in accordance with the electrical signal included in a frequency band different
from the frequency band of the electrical signal output from the electrical signal output means.
Can. Therefore, the electroacoustic transducer of the present invention changes the frequency
band of the electrical signal converted from the collected sound to a frequency band different
from the frequency band of the electrical signal output from the electrical signal output means of
the acoustic device of the present invention. Connection between the electro-acoustic transducer
and the acoustic device of the present invention and between the speaker and the acoustic device
of the present invention using a common cable The electro-acoustic transducer and the speaker
can be used simultaneously.
[0020]
Also, in the acoustic apparatus of the present invention, frequency conversion means for
converting the frequency band in which the electric signal generation means includes the electric
signal according to generation of the electric signal output from the electric signal output means.
, And the frequency conversion means comprises analog-to-digital conversion means for
converting the electrical signal from an analog signal to a digital signal. According to this
configuration, the audio apparatus of the present invention can change the frequency band of the
electrical signal corresponding to the generation of the electrical signal output from the electrical
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signal output means with a simple configuration.
[0021]
An acoustic system according to the present invention comprises the electroacoustic transducer
according to any one of claims 1 to 5, the acoustic device according to claim 6 or 7, and the
frequency conversion of the electroacoustic transducer. A signal line for transmitting both the
electric signal converted by the means and the electric signal output from the electric signal
output means, the frequency at which the electric signal converted by the frequency conversion
means of the electro-acoustic transducer is included The band is a frequency band other than the
frequency band in which the electrical signal output from the electrical signal output unit is
included, and the electrical signal generation unit converts the electrical signal converted by the
frequency conversion unit of the electroacoustic transducer. Accordingly, the electric signal
output from the electric signal output means is generated. With this configuration, the acoustic
system according to the present invention has different frequencies between the frequency band
of the electrical signal converted from the sound collected by the electroacoustic transducer and
the frequency band of the electrical signal output from the electrical signal output means by the
acoustic device. Since the band can be changed, the electroacoustic transducer and the acoustic
device, and the speaker and the acoustic device can be connected using a common cable, and the
electroacoustic transducer and the speaker Can be used simultaneously.
[0022]
DETAILED DESCRIPTION OF THE INVENTION Preferred embodiments of the present invention
will be described below with reference to the drawings. First Embodiment
[0023]
First, a first embodiment of the present invention will be described with reference to FIGS.
[0024]
First, the configuration of the sound system according to the present embodiment will be
described with reference to FIGS. 1 and 2. FIG.
[0025]
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8
In FIG. 1, a sound system 100 includes a sound collection microphone 110 as an electro-acoustic
transducer, a sound device 130, and a sound source device 150 for outputting a loud sound
signal for converting into a loud sound such as an announcement or BGM. And a power amplifier
160 for amplifying a loud sound signal output from the sound device 130 to the outside, and a
speaker 170 for converting the loud sound signal into a loud sound and outputting it.
[0026]
The sound collecting microphone 110 converts the ambient noise into a noise signal which is an
electric signal, and the frequency converting means converts the frequency band including the
noise signal converted by the electro acoustic converting means 111. And 120 are provided.
[0027]
As shown in FIG. 2, the frequency converting means 120 receives the noise signal converted by
the electro-acoustic converting means 111, the noise signal input terminal 121, and the noise
signal input to the noise signal input terminal 121. Analog band limiting filter 122 which limits
the frequency band included to a predetermined frequency band, for example, a band of
frequency 0 or more and less than fs / 2, and noise signal whose frequency band is limited by
analog band limiting filter 122 from analog signal to digital And an A / D converter 123 as an
analog-to-digital conversion means for converting into a signal.
[0028]
Here, according to the sampling theorem, the A / D converter 123 converts the input noise signal
into a digital signal at a sampling frequency fs which is twice or more of the highest frequency.
The noise signal output from the frequency divider 123 is symmetrical about the frequency fs / 2
which is 1/2 the sampling frequency fs in the band lower than the frequency fs, and in the band
higher than the frequency fs from the frequency 0 to the frequency fs The characteristics of the
signal are repeated infinitely in the cycle of the frequency bandwidth fs.
[0029]
Further, the frequency conversion means 120 converts the noise signal converted into a digital
signal by the A / D converter 123 from a digital signal into an analog signal, and the D / A
converter 124. An analog band limiting filter 125 for limiting a frequency band including a noise
signal converted into an analog signal to a predetermined frequency band, for example, a band
not less than the frequency fs and less than 3 fs / 2 And a noise signal output terminal 126 for
outputting the generated noise signal.
08-05-2019
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[0030]
As shown in FIG. 1, the acoustic device 130 comprises a noise signal input terminal 131 as an
electrical signal input means to which the noise signal outputted by the noise signal output
terminal 126 (see FIG. 2) is inputted, and a noise signal. An analog band limiting filter 132 for
limiting the frequency band including the noise signal input to the input terminal 131 to a
predetermined frequency band, for example, a band with a frequency fs or more and less than 3
fs / 2 And an A / D converter 133 for converting the limited noise signal from an analog signal to
a digital signal.
[0031]
Here, like the A / D converter 123 described above, the A / D converter 133 converts the input
noise signal into a digital signal at a sampling frequency fs that is twice or more the highest
frequency according to the sampling theorem. The noise signal output from the A / D converter
133 is symmetrical about the frequency fs / 2 which is half the sampling frequency fs in a band
lower than the frequency fs, and is frequency fs. In the above band, the characteristic of the band
from the frequency 0 to the frequency fs becomes a signal repeated infinitely in the cycle of the
frequency band width fs.
[0032]
Also, the sound device 130 outputs noise characteristic analysis means 134 for analyzing the
frequency characteristic level of the ambient noise from the noise signal converted into the
digital signal by the A / D converter 133, and the sound source device 150. A loudspeaker sound
signal input terminal 135 to which a loudspeaker sound signal is input, an analog band limiting
filter 136 for limiting a frequency band including the loudspeaker sound signal input to the
loudspeaker sound signal input terminal 135 to a predetermined frequency band, a loudspeaker
sound An A / D converter 137 is provided to convert the loud sound signal input to the signal
input terminal 135 from an analog signal to a digital signal.
[0033]
Also, the sound device 130 has a voice characteristic analysis means 138 for analyzing the
frequency characteristic level of the loud sound from the loud sound signal converted into a
digital signal by the A / D converter 137, and a noise characteristic analysis means 134. And a
compensation amount for compensating the loud sound signal inputted from the sound source
device 150 based on the frequency characteristic level of the ambient noise and the loud sound
analyzed by the loud sound characteristic analysis means 138, masking the loud sound by the
ambient noise And compensation amount calculating means 139 which calculates according to
the purpose such as compensating for.
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[0034]
Further, the sound device 130 changes the loud sound signal converted into the digital signal by
the A / D converter 137 in accordance with the compensation amount calculated by the
compensation amount calculating means 139, so that the volume and the sound quality of the
loud sound are obtained. Control means 140 for controlling the sound, a D / A converter 141 for
converting the speech signal changed by the sound control means 140 from a digital signal to an
analog signal, and an analog signal by the D / A converter 141 An analog band limiting filter 142
for limiting the frequency band including the loud voice signal to a predetermined frequency
band, and an electrical signal output for outputting a loud voice signal whose frequency band is
limited to the predetermined frequency band by the analog band limiting filter 142 A
loudspeaker sound signal output terminal 143 as a means is provided.
[0035]
Here, the analog band limit filter 132, A / D converter 133, noise characteristic analysis means
134, loud sound signal input terminal 135, analog band limit filter 136, A / D converter 137,
loud sound property analysis means 138, compensation amount calculating means 139, acoustic
control means 140, D / A converter 141, and analog band limiting filter 142 are electrical signals
for generating a loudspeaker sound signal as an electrical signal output from the loudspeaker
sound signal output terminal 143. It constitutes a generation means.
Further, the analog band limiting filter 132 and the A / D converter 133 constitute frequency
conversion means for converting a frequency band including a noise signal according to the
generation of the loud sound signal output from the loud sound signal output terminal 143.
There is.
[0036]
Note that the frequency band in which the noise signal converted by the frequency conversion
means 120 of the sound collection microphone 110 is included is a frequency band other than
the frequency band in which the loud sound signal output from the loud sound signal output
terminal 143 is included, It is equal to the frequency band in which the noise signal to which the
electrical signal generating means responds to generate the loud sound signal is included.
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In other words, the frequency pass band of the analog band limit filter 125 and the frequency
pass band of the analog band limit filter 132 are equal.
Therefore, the electric signal generation means is an electric signal included in a frequency band
other than the frequency band in which the loud sound signal output from the loud sound signal
output terminal 143 is included among the electric signals input from the noise signal input
terminal 131, According to the noise signal converted by the frequency conversion means 120 of
the sound collection microphone 110, a loud sound signal to be output from the loud sound
signal output terminal 143 is generated.
[0037]
The sound system 100 further includes a cable 101 as a signal line for transmitting both the
noise signal converted by the frequency conversion means 120 of the sound collection
microphone 110 and the loud sound signal output from the loud sound signal output terminal
143. There is.
[0038]
Next, the operation of the sound system according to the present embodiment will be described
with reference to FIGS.
[0039]
Description of the operation substantially similar to that of the conventional sound system shown
in FIGS. 13 and 14 will be omitted.
[0040]
In the acoustic system 100, ambient noise is picked up by the pick-up microphone 110 and
converted to a noise signal as shown in FIG. 3 (a).
When ambient noise is converted into a noise signal by the sound collection microphone 110, the
converted noise signal is input from the noise signal input terminal 121 to the inside of the
frequency conversion means 120, and then the frequency band is converted by the analog band
limiting filter 122. The frequency is limited to a band of 0 or more and less than fs / 2, and the
state shown in FIG. 3B is obtained.
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When the frequency band is limited by the analog band limiting filter 122, the noise signal is
converted from an analog signal to a digital signal by the A / D converter 123, and the state
shown in FIG. 3C is obtained.
The A / D converter 123 converts the noise signal into a digital signal at a sampling frequency fs
that is twice or more the highest frequency according to the sampling theorem.
[0041]
When the noise signal is converted from an analog signal to a digital signal by the A / D
converter 123, the D / A converter 124 converts the digital signal to an analog signal.
Even if the noise signal is converted into an analog signal by the D / A converter 124, the
frequency characteristic remains in the state shown in FIG. 3 (c).
[0042]
When the noise signal is converted into an analog signal by the D / A converter 124, the
frequency band is limited by the analog band limiting filter 125 to a frequency band not less
than fs and less than 3 fs / 2, as shown in FIG. It will be in the state shown.
When the frequency band is limited by the analog band limiting filter 125, the noise signal is
output from the noise signal output terminal 126 to the outside of the frequency conversion
means 120 and transmitted on the cable 101.
[0043]
Here, assuming that the loud sound signal as shown in FIG. 4B is outputted from the loud sound
signal output terminal 143, the noise signal outputted from the noise signal output terminal 126
is obtained on the cable 101. And the loud sound signal output from the loud sound signal
output terminal 143 are transmitted, and the state as shown in FIG. 5A is obtained.
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13
[0044]
When an electrical signal as shown in FIG. 5A, ie, a noise signal and a loud sound signal, is input
to the noise signal input terminal 131, the input electrical signal has a frequency controlled by
the analog band limiting filter 132. The band is limited to a band of the frequency fs or more and
less than 3 fs / 2, and the state shown in FIG. 5B is obtained.
In other words, the component of the loud sound signal is removed by the analog band limiting
filter 132 so that the input electrical signal is made only the component of the noise signal.
The electric signal whose frequency band is limited by the analog band limiting filter 132, that is,
the noise signal is converted from an analog signal to a digital signal by the A / D converter 133,
and the state shown in FIG. 5C is obtained.
[0045]
Here, in the state shown in FIG. 5C, the noise signal in the state shown in FIG. 3B is converted
into a digital signal by the A / D converter 133 at a sampling frequency fs which is twice or more
the highest frequency. It is equal to
Therefore, the acoustic system 100 operates in the same manner as when the noise signal
converted from ambient noise by the electroacoustic conversion means 111 is input to the A / D
converter 133 of the acoustic device 130 without converting the frequency band. do.
[0046]
The speaker 170 preferably has, for example, an analog band limiting filter as means for
removing the component of the noise signal and leaving only the component of the loud sound
signal.
However, if the frequency band of the noise signal transmitted on the cable 101 is outside the
08-05-2019
14
audible frequency band, or even if the noise signal is loudened from the speaker 170, the sound
reproduction capability of the speaker 170 is low, which causes a hearing problem. In the case
where the frequency band is such an unreasonable level, the speaker 170 may not be provided
with means for removing the component of the noise signal and leaving only the component of
the loud sound signal.
[0047]
Further, in the present embodiment, the noise signal is limited in frequency band to a frequency
band not less than the frequency fs and less than 3 fs / 2 by the analog band limiting filter 125,
and the state shown in FIG. According to the present invention, the frequency band of the noise
signal may be converted by the analog band limiting filter 125 into a frequency band different
from that of the loud sound signal output from the loud sound signal output terminal 143.
Therefore, for example, even if the noise signal is made to be in the state shown in FIG. 6A or FIG.
6B by the analog band limiting filter 125, the sound system 100 is not shown by the analog band
limiting filter 125. It is possible to obtain the same action as the above-described case in which
the state shown in 4 (a) is obtained.
[0048]
Further, in the present embodiment, the frequency conversion means 120 is configured as shown
in FIG. 2, but according to the present invention, the frequency conversion means 120 is a noise
converted by the electroacoustic conversion means 111. It is sufficient that the frequency band
in which the signal is included can be converted into a frequency band other than the frequency
band in which the loud sound signal output from the loud sound signal output terminal 143 is
included. It may be configured as the frequency converter 220 shown in FIG.
[0049]
The configuration of the frequency conversion means 220 shown in FIG. 7 and the operation of
the acoustic system 100 when the frequency conversion means 220 shown in FIG. 7 is used in
place of the frequency conversion means 120 in FIG. 1 will be described below.
[0050]
First, the configuration of the frequency conversion means 220 shown in FIG. 7 will be described.
08-05-2019
15
[0051]
As shown in FIG. 7, the frequency conversion means 220 receives a noise signal input terminal
221 to which the noise signal converted by the electroacoustic conversion means 111 is input
and a noise signal input to the noise signal input terminal 221. Analog band limiting filter 222
which limits the frequency band included to a predetermined frequency band, for example, a
band of frequency 0 or more and less than fs / 2, and noise signal whose frequency band is
limited by analog band limiting filter 222 from analog signal to digital And an A / D converter
223 as an analog-to-digital conversion means for converting into a signal.
[0052]
Here, according to the sampling theorem, the A / D converter 223 converts the input noise signal
into a digital signal at a sampling frequency fs which is twice or more the highest frequency, The
noise signal output from the unit 223 is symmetrical about the frequency fs / 2 which is 1/2 the
sampling frequency fs in the frequency band lower than the frequency fs, and the frequency
band 0 to the frequency fs in the frequency band fs or higher The characteristics of the signal are
repeated infinitely in the cycle of the frequency bandwidth fs.
[0053]
Further, the frequency conversion means 220 comprises upsampling means 224 as frequency
increasing means for increasing the sampling frequency of the noise signal converted to a digital
signal by the A / D converter 223 to an integral multiple, and upsampling means A digital band
limiting filter 225 which limits the frequency band including the noise signal whose sampling
frequency is increased by an integer multiple, for example, four, by 224 to a predetermined
frequency band, for example, a band of frequency fs or more and less than 3 fs / 2. And have.
[0054]
Here, the digital band limiting filter 225 is a general digital band limiting filter, and when the
sampling frequency of the signal input to the digital band limiting filter 225 is Fs, the digital
band limiting filter 225 outputs The signal to be selected is symmetrical about the frequency Fs /
2 which is 1/2 the sampling frequency Fs in the frequency band lower than the frequency Fs,
and in the frequency band higher than the frequency Fs, the characteristics of the frequency
band from the frequency 0 to the frequency Fs It becomes a signal repeated infinitely in a cycle
of width Fs.
[0055]
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The frequency converter 220 converts the noise signal whose frequency band is limited to a
predetermined frequency band by the digital band limiting filter 225, ie, the noise signal
converted into the digital signal by the A / D converter 223. A frequency band including a D / A
converter 226 for converting a signal into an analog signal and a noise signal converted into an
analog signal by the D / A converter 226 is a predetermined frequency band, for example, a
frequency fs or more and less than 3 fs / 2 And a noise signal output terminal 228 for outputting
a noise signal whose frequency band is limited by the analog band limiting filter 227.
[0056]
Next, the operation of the acoustic system 100 when the frequency converting means 220 shown
in FIG. 7 is used in place of the frequency converting means 120 in FIG. 1 will be described.
[0057]
In the sound system 100, the noise signal converted by the sound collection microphone 110 is
shown in FIG. 3C by the noise signal input terminal 221, the analog band limiting filter 222, and
the A / D converter 223. become.
The functions of the noise signal input terminal 221, the analog band limiting filter 222, and the
A / D converter 223 are the same as the functions of the noise signal input terminal 121, the
analog band limiting filter 122, and the A / D converter 123. Therefore, the explanation is
omitted.
[0058]
When the noise signal is converted into a digital signal by the A / D converter 223, it is input to
the upsampling means 224, and the sampling frequency fs is increased by four by the
upsampling means 224.
Here, assuming that n is an integer, the upsampling means 224 inputs the sampling interval fs of
the input noise signal when the noise signal whose sampling frequency is fs is input as shown in
FIG. 8A. The data is equally divided into n, and as shown in FIG. 8B, data having a level of 0
between sampled data (hereinafter referred to as 0 data).
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The sampling frequency fs of the noise signal to be input is increased by n times by inputting the
sampling interval fs at a time interval fs / n equally divided by n.
Incidentally, even if the noise signal has the sampling frequency fs increased fourfold by the
upsampling means 224, the frequency characteristic remains as shown in FIG. 3 (c).
[0059]
When the sampling frequency fs is made 4 times the sampling frequency 4 fs by the up sampling
means 224, the noise signal is 1⁄2 of the sampling frequency 4 fs in the frequency band of 4 fs
or less by the digital band limiting filter 225. The characteristic of the band from frequency 0 to
frequency 4 fs is infinitely repeated with a cycle of frequency bandwidth 4 fs in a band of
frequency 4 fs or more, and the state shown in FIG. .
The noise signal is frequency-limited by the digital band limiting filter 225, and then converted
from digital to analog by the D / A converter 226.
Even if the noise signal is converted into an analog signal by the D / A converter 226, the
frequency characteristic remains as shown in FIG.
[0060]
When the noise signal is converted into an analog signal by the D / A converter 226, the
frequency band is limited by the analog band limiting filter 227 to a frequency band not less
than fs and less than 3 fs / 2, as shown in FIG. It will be in the state shown.
When the frequency band is limited by the analog band limiting filter 227, the noise signal is
output from the noise signal output terminal 228 to the outside of the frequency conversion
means 220 and transmitted on the cable 101.
Note that the subsequent action of the acoustic system 100 when the frequency conversion
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means 220 shown in FIG. 7 is used in place of the frequency conversion means 120 in FIG. 1 is
the same as the above-described action of the acoustic system 100 shown in FIG. I omit
explanation.
[0061]
In the present embodiment, the upsampling means 224 is configured to increase the sampling
frequency of the noise signal to an integral multiple, but according to the present invention, the
upsampling means 224 is a noise signal. The sampling frequency of may be increased by, for
example, 3/2 times other than an integral multiple.
[0062]
Here, the up-sampling means 224 can increase the sampling frequency of the noise signal to
other than an integral multiple by performing the processing described below.
The upsampling means 224 inputs the 0 data to the noise signal in the same manner as when
increasing the sampling frequency of the noise signal to an integral multiple, so that the
sampling frequency of the noise signal input to the upsampling means 224 is A sample of the
noise signal input to the upsampling means 224 which is the least common multiple of the
sampling frequency of the noise signal input to the upsampling means 224 and the sampling
frequency of the noise signal scheduled to be output from the upsampling means 224 Increase to
a frequency that is an integral multiple of the
The upsampling unit 224 performs decimation processing, interpolation processing, and the like
on the noise signal whose frequency has been increased to an integral multiple, and the sampling
frequency of the noise signal input to the upsampling unit 224 is not integer multiple. increase.
[0063]
Hereinafter, the configuration of the frequency conversion means 320 shown in FIG. 10 and the
operation of the acoustic system 100 when the frequency conversion means 320 shown in FIG.
10 is used in place of the frequency conversion means 120 in FIG. 1 will be described.
[0064]
First, the configuration of the frequency conversion means 320 shown in FIG. 10 will be
08-05-2019
19
described.
[0065]
As shown in FIG. 10, the frequency conversion means 320 has a noise signal input terminal 321
to which the noise signal converted by the electroacoustic conversion means 111 is input and a
noise signal input to the noise signal input terminal 321. Analog band limiting filter 322 which
limits the frequency band included to a predetermined frequency band, for example, a band of
frequency 0 or more and less than fs / 2, and noise signal whose frequency band is limited by
analog band limiting filter 322 from analog signal to digital An A / D converter 323 as an analogto-digital conversion means for converting into a signal is provided.
[0066]
Here, according to the sampling theorem, the A / D converter 323 converts the input noise signal
into a digital signal at a sampling frequency of 4 fs which is twice or more of the highest
frequency. The noise signal output from the mixer 323 is symmetrical about the frequency 2 fs
which is 1/2 the sampling frequency 4 fs in the frequency band of 4 fs or less, and the
characteristics of the frequency band 0 to 4 fs in the frequency band of 4 fs or more Is an
infinitely repeated signal with a cycle of frequency bandwidth 4 fs.
[0067]
The frequency conversion means 320, which will be described in detail later, comprises buffering
means 324, windowing means 325, FFT means 326, frequency data changing means 327, IFFT
means 328, and buffering means 329. There is.
[0068]
Further, the frequency conversion means 320 converts the noise signal converted into a digital
signal by the A / D converter 323 from a digital signal into an analog signal, and the D / A
converter 330 The frequency band is limited by the analog band limiting filter 331 and the
analog band limiting filter 331. The analog band limiting filter 331 limits the frequency band
including the noise signal converted into the analog signal to a predetermined frequency band,
for example, a band of frequency fs or more and less than 3 fs / 2. And a noise signal output
terminal 332 for outputting the generated noise signal.
[0069]
Next, the operation of the acoustic system 100 when the frequency converting means 320 shown
in FIG. 10 is used in place of the frequency converting means 120 in FIG. 1 will be described.
08-05-2019
20
[0070]
In the sound system 100, ambient noise is picked up by the pickup microphone 110 and
converted into a noise signal as shown in FIG. 3 (a).
When ambient noise is converted into a noise signal by the sound collecting microphone 110, the
converted noise signal is input from the noise signal input terminal 321 into the inside of the
frequency conversion means 320, and then the frequency band is converted by the analog band
limiting filter 322. The frequency is limited to a band of 0 or more and less than fs / 2, and the
state shown in FIG. 3B is obtained.
When the frequency band is limited by the analog band limiting filter 322, the noise signal is
converted from an analog signal to a digital signal by the A / D converter 323, and the state
shown in FIG. 11A is obtained.
Note that the A / D converter 323 converts the noise signal into a digital signal at a sampling
frequency 4 fs that is twice or more the highest frequency in accordance with the sampling
theorem.
[0071]
When the noise signal is converted into a digital signal by the A / D converter 323, the buffering
means 324 accumulates the noise signal which is time-series data.
When a certain number of samples are accumulated in the buffering means 324, the noise signal
is extracted by the windowing means 325 so as to overlap each half of the data length used for
the FFT processing, and accumulated data using the Hamming window, Hanning window, etc.
The first and last parts of are processed to converge to an amplitude of 0.
When data processing is performed by windowing means 325 so that the first and last parts of
the accumulated data converge to amplitude 0, the noise signal is converted from time series
08-05-2019
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data to frequency data by FFT processing means 326, and the converted frequency is obtained.
The data is replaced, inserted, changed, etc. by the frequency data changing means 327 so that it
becomes a frequency band other than the frequency band in which the noise signal converted by
the electroacoustic conversion means 111 is included, as shown in FIG. It will be in the state
shown.
This change processing is processed so as to maintain complex conjugate relationship around the
Nyquist frequency 2 fs based on the property of the digital signal so that frequency data is
converted to time series data by IFFT processing described later to become actual data. Ru.
[0072]
The frequency data whose frequency band has been converted by the frequency data changing
means 327 is converted into time series data by the IFFT processing means 328, and then is
overlapped by half of the data length of IFFT processing by the buffering means 329.
Accumulated.
The noise signal is converted by the D / A converter 330 from a digital signal to an analog signal
when it is summed and accumulated by the buffering means 329.
Even if the noise signal is converted into an analog signal by the D / A converter 330, the
frequency characteristic remains as shown in FIG.
[0073]
When the noise signal is converted into an analog signal by the D / A converter 330, the
frequency band is limited by the analog band limiting filter 331 to a frequency band not less
than fs and less than 3 fs / 2, as shown in FIG. It will be in the state shown.
Since the subsequent action of the acoustic system 100 when the frequency conversion means
320 shown in FIG. 10 is used instead of the frequency conversion means 120 in FIG. 1 is the
same as the above-described action of the acoustic system 100 shown in FIG. I omit explanation.
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Second Embodiment
[0074]
Next, a second embodiment of the present invention will be described with reference to FIG.
[0075]
In FIG. 12, the configuration of an acoustic system 400 according to this embodiment is
substantially the same as that of the acoustic system 100 according to the first embodiment,
except for the points described below.
[0076]
The sound system 400 includes a sound collection microphone 410 in place of the sound
collection microphone 110 of the sound system 100 according to the first embodiment.
Similarly to the sound collection microphone 110 of the sound system 100 according to the first
embodiment, the sound collection microphone 410 converts the ambient noise into a noise
signal, and the noise signal converted by the noise conversion means 411. And a frequency
conversion means 412 for converting the frequency band in which the signal is included into a
frequency band other than the frequency band in which the loud sound signal output from the
loud sound signal output terminal 143 is included.
In addition, the sound collection microphone 410 has a frequency band in which the noise signal
converted by the electroacoustic conversion means 411 is included in the frequency conversion
means 412, and a frequency band other than the frequency band in which the speech signal
output from the speech sound signal output terminal 143 is included. Conversion determining
means 413 for determining whether or not to convert to a frequency band. The acoustic system
400 is configured so that the electroacoustic transducer 411 can convert the loud sound signal
output from the loud sound signal output terminal 143 into a loud sound.
[0077]
Also, the operation of the sound system 400 according to the present embodiment can be used
as the sound collection microphone and speaker while the sound collection microphone 410 can
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be used as a sound collection microphone and a speaker. Is the same as the operation of the
acoustic system 100 according to the first embodiment except that it can be determined.
[0078]
As described above, according to the present invention, the electroacoustic transducer and the
acoustic device, and the speaker and the acoustic device are connected using a common cable.
The electro-acoustic transducer and the speaker can be used simultaneously.
[0079]
Brief description of the drawings
[0080]
1 is a block diagram of an acoustic system according to a first embodiment of the present
invention.
[0081]
2 is a block diagram showing an example of the frequency conversion means of the sound
collection microphone of the sound system shown in FIG.
[0082]
3 is a frequency characteristic diagram of the electrical signal in the acoustic system shown in
FIG.
[0083]
4 is a frequency characteristic diagram in a state different from the state shown in FIG. 3 of the
electrical signal in the acoustic system shown in FIG.
[0084]
5 is a frequency characteristic diagram in a state different from the state shown in FIGS. 3 and 4
of the electrical signal in the acoustic system shown in FIG.
[0085]
6 is a frequency characteristic diagram in a state different from the state shown in FIGS. 3 to 5 of
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the electrical signal in the acoustic system shown in FIG.
[0086]
7 is a block diagram showing an example different from the example shown in FIG. 2 of the
frequency conversion means of the sound collection microphone of the sound system shown in
FIG.
[0087]
8 is a diagram for explaining the up-sampling means of the frequency conversion means shown
in FIG.
[0088]
9 is a frequency characteristic diagram in a state different from the state shown in FIGS. 3 to 6 of
the electrical signal in the acoustic system shown in FIG.
[0089]
10 is a block diagram showing an example different from the example shown in FIGS. 2 and 7 of
the frequency conversion means of the sound collection microphone of the sound system shown
in FIG.
[0090]
11 is a frequency characteristic diagram in a state different from the state shown in FIGS. 3 to 6
and 9 of the electrical signal in the acoustic system shown in FIG.
[0091]
12 is a block diagram of an acoustic system according to a second embodiment of the present
invention.
[0092]
13 is a block diagram of a conventional sound system.
[0093]
14 is a block diagram of a conventional acoustic system different from the acoustic system
08-05-2019
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shown in FIG.
[0094]
Explanation of sign
[0095]
111, 411 electro-acoustic conversion means 120, 220, 320, 412 frequency conversion means
110, 410 sound collection microphone (electro-acoustic converter) 413 conversion
determination means 123, 223, 323 A / D converter (analog-digital conversion means) 124 226,
330 D / A converter (digital-analog conversion means) 224 up-sampling means (frequency
increase means) 131 Noise signal input terminal (electric signal input means) 143 Loud sound
signal output terminal (electric signal output means) 132 Analog band Limiting filter (electric
signal generation means, frequency conversion means) 133 A / D converter (electric signal
generation means, frequency conversion means, analog-to-digital conversion means) 134 Noise
characteristic analysis means (electric signal generation means) 135 Loud sound signal input
terminal (Electric signal generation means) 136 Analog band-limited fill (Electric signal
generation means) 137 A / D converter (electric signal generation means) 138 Loud sound
characteristic analysis means (electric signal generation means) 139 Compensation amount
calculation means (electric signal generation means) 140 Acoustic control means (electric signal
generation means ) 141 D / A converter (electrical signal generating means) 142 Analog band
limiting filter (electrical signal generating means) 130 Acoustic device 101 Cable (signal line)
100, 400 Acoustic system
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