JP2015070356

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DESCRIPTION JP2015070356
The present invention provides a technology for reproducing an audio signal at an appropriate
volume level while suppressing wasteful power consumption. A speaker switching device adjusts
a volume level according to a volume level adjustment amount instructed by a control unit with a
volume adjustment unit, and an operation unit detects a frequency distribution of an audio
signal, and a storage unit. Stores the volume level adjustment amount when the speakers are
switched, switches and uses the speakers 2A and 2B having different frequency characteristics
according to the audio signal to be reproduced, and reproduces them according to the speakers
2A and 2B to be used Adjust the output volume level of the audio signal. The audio signal supply
destination is switched between the speaker 2A having wide-band frequency characteristics and
the speaker 2B having narrow-band frequency characteristics, and the output volume level in the
audio band where the output volume level is maximum in the speaker 2B is the speaker Adjust
the output volume level of the audio signal to be the same as the output volume level in the audio
band at 2A. [Selected figure] Figure 1
Speaker switching device and audio device
[0001]
The present invention relates to a speaker switching technology for switching a plurality of
speakers having different frequency characteristics.
[0002]
Patent Document 1 discloses a television receiver capable of suppressing sounds other than voice
in a time zone such as midnight.
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1
[0003]
This television receiver has a switch and a band pass filter provided between an audio signal
processing circuit and a speaker, and a control unit.
The band pass filter passes only audio signals in the voice band and filters audio signals in other
bands.
The control unit controls the switch such that the audio signal processing circuit and the speaker
are connected via the band filter in the preset night mode time zone. Further, in a time zone other
than the nighttime mode time zone, the switch is controlled so that the audio signal processing
circuit and the speaker are directly connected.
[0004]
Therefore, in the nighttime mode time zone, a band-pass filter is operated to emphasize human
sound, while suppressing the other sounds makes it easy to hear human voice even if the volume
is reduced. . In addition, in the time zone other than the night mode time zone, sound can be
output normally.
[0005]
JP 2005-328177
[0006]
As described above, in the television receiver described in Patent Document 1, the band other
than the voice band is filtered by the band filter to suppress the sound other than the voice.
For this reason, in the time zone such as midnight, only the audio signal of the voice band is
output from the speaker via the band pass filter, but in the technology described in Patent
Document 1, the band is filtered by the band pass filter and not output from the speaker It does
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not take into account the power that is wasted for the audio signal of.
[0007]
The present invention has been made in view of the above circumstances, and an object thereof
is to provide a technique for reproducing an audio signal at an appropriate volume level while
suppressing wasteful power consumption.
[0008]
In order to solve the above-mentioned subject, in the present invention, a plurality of speakers
with different frequency characteristics are switched and used.
Then, according to the speaker to be used, the volume level of the audio signal to be reproduced
is adjusted. For example, in the case where the audio signal supply destination is switched
between a speaker having a wide band frequency characteristic and a speaker having a narrow
band frequency characteristic, the speaker having the narrow band frequency characteristic has
a maximum volume level in the band. The volume level of the audio signal to be reproduced is
adjusted so that the volume level is the same as the volume level in the same band in the speaker
having wide band frequency characteristics.
[0009]
For example, the speaker switching device according to the present invention is a speaker
switching device connected to a plurality of speakers having different frequency characteristics,
and the switching unit switches the supply destination of the audio signal from among the
plurality of speakers; When the audio signal supply destination is switched, the volume level of
the audio signal is adjusted according to the volume level adjustment amount determined
according to the difference between the frequency characteristic of the speaker before switching
and the frequency characteristic of the speaker after switching Volume control means for
[0010]
Here, when the supply destination of the audio signal is switched between a speaker having a
wide band frequency characteristic and a speaker having a narrow band frequency characteristic,
the volume level is maximized in the speaker having the narrow band frequency characteristic.
The volume level adjustment amount may be set such that the volume level in the band is the
same as the volume level in the same band in the speaker having the wide-band frequency
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characteristic.
[0011]
In the present invention, since the volume level of the audio signal to be reproduced is adjusted
according to the speaker used, the audio signal can be reproduced at an appropriate volume level
while suppressing the power consumption.
In particular, a speaker having a narrow band frequency characteristic has higher efficiency than
a speaker having a wide band frequency characteristic because the speaker has a narrow band
compared to a speaker having a wide band frequency characteristic and the volume level is
maximum. .
For this reason, when switching the audio signal supply destination between a speaker having
wide-band frequency characteristics and a speaker having narrow-band frequency
characteristics, in a band where the volume level is maximum in the speaker having narrow-band
frequency characteristics. The audio signal is reproduced by the speaker having the narrow band
frequency characteristic by adjusting the sound level of the audio signal so that the volume level
of the speaker is the same as the sound level in the same band in the speaker having the wide
band frequency characteristic The audio signal can be reproduced at an appropriate volume level
while reducing power consumption in the case.
[0012]
FIG. 1 is a schematic functional block diagram of an audio device according to a first embodiment
of the present invention. FIG. 2 is a diagram showing frequency characteristics of the speakers
2A and 2B shown in FIG. FIG. 3 is a schematic functional block diagram of an audio device
according to a second embodiment of the present invention.
[0013]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings. First Embodiment FIG. 1 is a schematic functional block diagram of an audio device
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according to a first embodiment of the present invention.
[0014]
As illustrated, the audio device according to the present embodiment is configured to include a
speaker switching device 1 to which an audio signal is input, and two speakers 2A and 2B
connected to the speaker switching device 1.
[0015]
The speakers 2A, 2B have mutually different frequency characteristics.
FIG. 2 is a diagram showing frequency characteristics of the speakers 2A and 2B. In this figure,
the solid line 20 shows the frequency characteristic of the speaker 2A, and the dotted line 21
shows the frequency characteristic of the speaker 2B.
[0016]
As illustrated, the speaker 2A is a wideband speaker that holds an output volume level of a
predetermined value or more over a wider frequency band than the speaker 2B, and the speaker
2B has a predetermined value or more only in the audio band (around 1 KHz) A narrow band
speaker that holds the output volume level of Therefore, the speaker 2A is suitable for
reproducing a wide band audio signal such as music, and the speaker 2B is suitable for
reproducing a narrow band audio signal such as news, talk program and the like in which a large
part is occupied.
[0017]
Note that, as illustrated, the narrow band speaker 2B is an audio band in which the output sound
volume level is maximized because the narrow band holding the output sound volume level equal
to or higher than the predetermined value is compared with the speaker 2A which is a wide band
speaker. The output volume level at (about 1 KHz) is higher by ΔT (dB) than the output volume
level in the audio band of the speaker 2A. For this reason, when the supply destination of the
audio signal is switched from the speaker 2A to the speaker 2B, the output volume level of the
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audio band rapidly increases, which may surprise the viewer or cause the user to feel discomfort.
[0018]
Returning to FIG. 1, the description will be continued. The speaker switching device 1 switches
the audio signal supply destination to one of the speakers 2A and 2B according to the audio
signal to be reproduced, and reproduces the audio signal according to the speaker 2A or 2B to
which the audio signal is supplied. Adjust the volume level of. As illustrated, the speaker
switching device 1 includes an audio signal input unit 10, a volume adjustment unit 11, a
speaker switching unit 12, an operation unit 13, a storage unit 14, and a control unit 15.
[0019]
The audio signal input unit 10 is an input terminal for inputting an audio signal.
[0020]
The volume adjustment unit 11 adjusts the volume level of the audio signal input to the audio
signal input unit 10 in accordance with the volume level adjustment amount instructed from the
control unit 15.
[0021]
The speaker switching unit 12 switches the supply destination of the audio signal output from
the volume adjustment unit 11 to any one of the speakers 2A and 2B according to the instruction
of the control unit 15.
[0022]
The operation unit 13 performs FFT (Fast Fourier Transform) processing on the audio signal
input to the audio signal input unit 10 to detect the frequency distribution of the audio signal.
[0023]
The storage unit 14 stores the volume level adjustment amount C1 when the audio signal supply
destination is switched from the speaker 2A to the speaker 2B and the volume level adjustment
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amount C2 when the speaker 2B is switched to the speaker 2A. There is.
As described above, in the speaker 2B which is a narrow band speaker, the output volume level
in the voice band at which the output volume level is maximum is ΔT (dB relative to the output
volume level in the voice band of the speaker 2A which is a wide band speaker. )high.
Therefore, when the audio signal supply destination is switched from the speaker 2A to the
speaker 2B, the volume level of the audio signal is decreased by ΔT (dB) as indicated by
reference numeral 22 in FIG. 2 (volume level adjustment amount C1 = −ΔT Conversely, when
switching from the speaker 2B to the speaker 2A, the volume level of the audio signal is
increased by ΔT (dB) (volume level adjustment amount C2 = + ΔT (dB)).
By doing this, when switching the speakers 2A and 2B, the volume level of the audio signal is
adjusted so that the output volume level of the voice band becomes the same before and after the
speaker switching.
[0024]
The control unit 15 determines the supply destination of the audio signal from the speakers 2A
and 2B based on the frequency distribution of the audio signal detected by the calculation unit
13.
That is, if the frequency distribution of the audio signal indicates a wide band characteristic over
the entire audible band such as music, the speaker 2A is determined as the supply destination of
the audio signal, and the voice band such as news and talk program occupies most. If the narrow
band characteristic is shown, the speaker 2B is determined as the supply destination of the audio
signal. Specifically, if the frequency distribution of the audio signal falls within the range of the
predetermined band including the audio band, the speaker 2B is selected as a supply destination
of the audio signal, and if exceeding the range of the predetermined band, the speaker 2A Choose
[0025]
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In the speaker switching device 1 configured as described above, the audio signal input to the
audio signal input unit 10 is input to the volume adjustment unit 11 and the calculation unit 13.
The operation unit 13 performs FFT processing on the input audio signal to detect the frequency
distribution of the audio signal, and outputs the frequency distribution to the control unit 15. The
control unit 15 determines the speakers 2A and 2B to which the audio signal is supplied based
on the frequency distribution of the input audio signal.
[0026]
Here, when the supply destination of the audio signal is switched from the speaker 2A to the
speaker 2B, the volume level adjustment amount C1 is read from the storage unit 14. Then, the
speakers are switched so that the switching of the supply destination of the audio signal from the
speaker 2A to the speaker 2B by the speaker switching unit 12 and the volume level adjustment
for the volume level adjustment amount C1 of the audio signal by the volume adjustment unit 11
are simultaneously performed. The switching unit 12 and the volume adjustment unit 11 are
controlled. As a result, the volume level of the audio signal input to the audio signal input unit 10
is lowered by ΔT (dB), and then the audio signal is reproduced from the speaker 2B.
[0027]
When the supply destination of the audio signal is switched from the speaker 2B to the speaker
2A, the volume level adjustment amount C2 is read out from the storage unit 14. Then, the
speakers are switched so that the switching of the supply destination of the audio signal from the
speaker 2B to the speaker 2A by the speaker switching unit 12 and the volume level adjustment
for the volume level adjustment amount C2 of the audio signal by the volume adjustment unit 11
are simultaneously performed. The switching unit 12 and the volume adjustment unit 11 are
controlled. As a result, the audio signal input to the audio signal input unit 10 is raised in volume
level by ΔT (dB), and thereafter reproduced from the speaker 2A.
[0028]
The first embodiment of the present invention has been described above.
[0029]
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In the present embodiment, the speaker switching device 1 switches and uses the two speakers
2A and 2B having different frequency characteristics, and adjusts the volume level of the audio
signal to be reproduced according to the speakers 2A and 2B to be used.
Specifically, when the supply destination of the audio signal is switched between the speaker 2A
having wide-band frequency characteristics and the speaker 2B having narrow-band frequency
characteristics, the output volume levels of the speakers before and after switching become
approximately the same. Adjust the volume level of the audio signal as (for example, the output
volume level in the audio band where the output volume level is maximum in the speaker 2B is
the same as the output volume level in the audio band in the speaker 2A) . Therefore, when
reproducing an audio signal while switching the two speakers 2A and 2B, the output volume
level of the speaker 2B having the larger maximum output volume level is about the same as the
speaker 2A having the smaller maximum output volume level. Power consumption can be
reduced. For example, when the difference ΔT (dB) between the output volume level in the audio
band of the speaker 2B and the output volume level in the audio band of the speaker 2A is 12
(dB), the output volume level of the speaker 2B is 12 (dB) By lowering the voltage, the output
power from the amplifier can be halved as compared to the case where the audio signal is
reproduced from the speaker 2B without adjusting the output volume level, and the power
consumption can be reduced accordingly. .
[0030]
In addition, when reproducing a narrow-band audio signal in which the voice such as news and
talk program occupies most, if the audio signal supply destination is switched to the narrow-band
speaker 2B without filtering the audio signal. Since it is good, power consumption can be further
suppressed.
[0031]
Therefore, according to the present embodiment, the output volume level of the audio band is
reduced when the supply destination of the audio signal is switched between the speakers 2A
and 2B while the power consumption in the case of reproducing the audio signal by the speaker
2B is reduced. The audio signal can be reproduced at an appropriate volume level so as not to
change rapidly.
[0032]
Further, in the present embodiment, the audio signal is subjected to FFT processing to detect a
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frequency distribution, and the speakers 2A and 2B are switched based on the detected
frequency distribution.
Therefore, the speakers 2A and 2B suitable for the audio signal to be reproduced can be
determined as the supply destination of the audio signal.
[0033]
In the present embodiment, the audio signal is subjected to FFT processing to detect the
frequency distribution, and the speakers 2A and 2B are switched based on the detected
frequency distribution. However, the present invention is not limited to this.
For example, if a genre code is added to the audio signal as in a digital broadcast signal, the
speakers 2A and 2B may be switched based on the genre code. Specifically, when the genre code
indicates audio-based content such as news or talk program, the speaker 2B is determined as the
audio signal supply destination, and in other cases, the speaker 2A is the audio signal supply
destination Decide on. Second Embodiment FIG. 3 is a schematic functional block diagram of an
audio device according to a second embodiment of the present invention.
[0034]
As illustrated, the audio device according to the present embodiment includes a speaker
switching device 1A to which an audio signal is input, and two speakers 2C, 2D and a
microphone 3 connected to the speaker switching device 1A. Be done.
[0035]
The speakers 2C and 2D have mutually different frequency characteristics, and are removably
connected to the speaker switching device 1A via a plug (not shown).
[0036]
The microphone 3 collects the reproduction sound output from the speakers 2C and 2D
connected to the speaker switching device 1A.
[0037]
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The speaker switching device 1A detects the frequency distribution of the reproduced sound
from each of the speakers 2C and 2D collected by the microphone 3, and stores these as the
frequency characteristics of the speakers 2C and 2D.
Also, according to the degree of matching between the frequency distribution of the audio signal
to be reproduced and the frequency characteristics of the speakers 2C and 2D, the audio signal
supply destination is switched to any one of the speakers 2C and 2D, and the speaker of the
audio signal supply destination Adjust the volume level of the audio signal to be played according
to 2C and 2D.
As illustrated, the speaker switching device 1A includes an audio signal input unit 10, a volume
adjustment unit 11, a speaker switching unit 12, an arithmetic unit 13, a storage unit 14A, a
control unit 15A, and an audio signal output unit 16A. , 16B, a sound source unit 17, a first input
switching unit 18A, and a second input switching unit 18B.
Here, components having the same functions as those of the speaker switching device 1
according to the first embodiment are denoted by the same reference numerals, and the detailed
description thereof is omitted.
[0038]
The storage unit 14A stores frequency characteristics of the speakers 2C and 2D.
[0039]
The audio signal output units 16A and 16B are jacks for connecting the speakers 2C and 2D.
The audio signal is output to the speaker 2C through the audio signal output unit 16A, or is
output to the speaker 2D through the audio signal output unit 16B.
[0040]
The sound source unit 17 generates an audio signal (noise signal) having uniform characteristics
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over the entire audible range, such as white noise and pink noise.
[0041]
The first input switching unit 18A switches the supply source of the audio signal input to the
speaker switching unit 12 to either one of the volume adjustment unit 11 and the sound source
unit 17 according to an instruction of the control unit 15A.
[0042]
The second input switching unit 18B switches the supply source of the audio signal input to the
calculation unit 13 to any one of the audio signal input unit 10 and the microphone 3 according
to the instruction of the control unit 15A.
[0043]
The control unit 15A operates in either the speaker characteristic detection mode or the audio
reproduction mode in accordance with the instruction of the operator input through the
operation panel (not shown).
[0044]
In the speaker characteristic detection mode, control unit 15A controls first input switching unit
18A and second input switching unit 18B to input the audio signal (noise signal) generated by
sound source unit 17 to speaker switching unit 12. At the same time, the audio signal collected
by the microphone 3 is input to the calculation unit 13.
In addition, the speaker switching unit 12 is controlled to switch the speakers 2C and 2D in
order, and the audio signal generated by the sound source unit 17 is sequentially supplied to the
speakers 2C and 2D.
Then, the reproduction sound of each of the speakers 2C and 2D is collected by the microphone
3, and the frequency distribution of the audio signal is detected by the calculation unit 13, and
these are stored in the storage unit 14A as the frequency characteristics of the respective
speakers 2C and 2D.
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[0045]
On the other hand, in the audio reproduction mode, the control unit 15A controls the first input
switching unit 18A and the second input switching unit 18B to input the audio signal output
from the volume adjustment unit 11 to the speaker switching unit 12, and The audio signal input
to the audio signal input unit 10 is input to the calculation unit 13.
Then, based on the frequency distribution of the audio signal detected by the calculation unit 13
and the frequency characteristics of the speakers 2C and 2D stored in the storage unit 14A, the
supply destination of the audio signal from the speakers 2C and 2D is determined.
That is, the speakers 2C and 2D having frequency characteristics with high degree of matching
(degree of matching) with the frequency distribution of the audio signal are determined as the
audio signal supply destination.
[0046]
Further, in the audio reproduction mode, when the supply destination of the audio signal is
switched, the control unit 15A instructs the volume adjustment unit 11 to maintain the output
volume level of the audio band at the same level before and after switching. Determine the
adjustment amount.
[0047]
In the speaker switching device 1A configured as described above, in the case of the speaker
characteristic detection mode, the audio signal (noise signal) generated by the sound source unit
17 is first reproduced by the speaker 2C, and the reproduced sound is collected by the
microphone 3 It is input to the calculation unit 13.
The operation unit 13 performs FFT processing on the input audio signal to detect the frequency
distribution of the audio signal, and outputs the frequency distribution to the control unit 15A.
The control unit 15A stores the input frequency distribution in the storage unit 14A as the
frequency characteristic of the speaker 2C.
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[0048]
Next, the audio signal generated by the sound source unit 17 is reproduced by the speaker 2 D,
and the reproduced sound is collected by the microphone 3 and input to the calculation unit 13.
The operation unit 13 performs FFT processing on the input audio signal to detect the frequency
distribution of the audio signal, and outputs the frequency distribution to the control unit 15A.
The control unit 15A stores the input frequency distribution in the storage unit 14A as the
frequency characteristic of the speaker 2D.
[0049]
As described above, the frequency characteristics of the speakers 2C and 2D are stored in the
storage unit 14A.
[0050]
On the other hand, in the case of the audio reproduction mode, the audio signal input to the
audio signal input unit 10 is input to the volume adjustment unit 11 and the calculation unit 13.
The operation unit 13 performs FFT processing on the input audio signal to detect the frequency
distribution of the audio signal, and outputs the frequency distribution to the control unit 15A.
The control unit 15A refers to the storage unit 14A, identifies the speakers 2C and 2D having a
frequency characteristic having a high degree of matching with the frequency distribution of the
input audio signal, and identifies the identified speakers 2C and 2D as audio signals. Decide on
the supply destination.
[0051]
Here, when the supply destination of the audio signal is switched, the control unit 15A
determines the volume level adjustment amount so that the output volume level of the audio
band is maintained at the same level before and after the switching. Specifically, the difference
ΔT (dB) of the output volume level of the audio band indicated by the frequency characteristics
of the two speakers 2C and 2D stored in the storage unit 14A is determined, and the audio band
indicated by the frequency characteristic of the speaker after switching If the output volume level
of the speaker is higher than the output volume level of the voice band indicated by the
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frequency characteristic of the speaker before switching is .DELTA.T (dB), the volume level
adjustment amount is determined to -.DELTA.T (dB), and the speaker frequency after switching If
the output volume level of the voice band indicated by the characteristics is ΔT (dB) lower than
the output volume level of the voice band indicated by the frequency characteristic of the
speaker before switching, the volume level adjustment amount is determined as + ΔT (dB). Then,
the speaker switching unit 12 and the volume adjusting unit 11 are configured so that the
switching of the speakers 2C and 2D by the speaker switching unit 12 and the volume level
adjustment for the volume level adjustment amount of the audio signal by the volume adjusting
unit 11 are simultaneously performed. Control. As a result, the volume level of the audio signal
input to the audio signal input unit 10 is adjusted according to the volume level adjustment
amount, and thereafter, the audio signal is reproduced from the speakers 2C and 2D to which the
audio signal is supplied.
[0052]
The second embodiment of the present invention has been described above.
[0053]
In the present embodiment, the speaker switching device 1A detects the frequency
characteristics of the speakers 2C and 2D connected to the audio signal output units 16A and
16B in the speaker characteristic detection mode, and stores the detected frequency
characteristics in the storage unit 14A.
Then, in the audio reproduction mode, the speakers 2C and 2D having a frequency characteristic
having a higher degree of matching with the frequency distribution of the audio signal input to
the audio signal input unit 10 are determined as the audio signal supply destination, and the
audio signal is supplied. When the destination is switched, the volume level adjustment amount is
determined so that the output volume level of the audio band is maintained at the same level
before and after the switching. Therefore, even when the speakers 2C and 2D connected to the
speaker switching device 1A are changed, the audio signal supply destination is switched
between the speakers 2C and 2D while suppressing the power consumption and reducing the
power consumption. The audio signal can be reproduced at an appropriate volume level so that
the output volume level of the band does not change suddenly.
[0054]
The present invention is not limited to the above-described embodiments, and various
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modifications can be made within the scope of the invention.
[0055]
For example, in each of the above embodiments, the case where the speaker switching devices 1
and 1A switch the supply destination of the audio signal from the two speakers according to the
audio signal to be reproduced has been described as an example.
However, the present invention is not limited to this. The supply destination of the audio signal
may be switched from three or more speakers according to the audio signal to be reproduced.
[0056]
Further, the functional configurations of the speaker switching devices 1 and 1A shown in FIGS.
1 and 3 may be realized as hardware by an integrated logic IC such as an application specific
integrated circuit (ASIC) or a field programmable gate array (FPGA). Or may be softwareimplemented by a computer such as a DSP (Digital Signal Processor) or a microcomputer.
[0057]
1, 1A: Speaker switching device, 2A to 2D: Speaker, 3: Microphone, 10: Audio signal input unit,
11: Volume adjustment unit, 12: Speaker switching unit, 13: Arithmetic unit, 14, 14A: Storage
unit, 15 , 15A: control unit, 16A, 16B: audio signal output unit, 17: sound source unit, 18A: first
input switching unit, 18B: second input switching unit
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