JPH1070795

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DESCRIPTION JPH1070795
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
sound image control apparatus used for electronic musical instruments, game machines, audio
equipment and the like.
[0002]
2. Description of the Related Art Electronic musical instruments, game machines, audio
equipment and the like use a configuration for localizing a sound image at an arbitrary position
for the purpose of obtaining a sense of reality.
[0003]
In these devices, a sound image localization configuration for an open sound system such as a
stereo speaker system or a sound image localization structure for a non-open sound system using
headphones or the like is used. However, when they use a dedicated hardware configuration, and
therefore an additional configuration that can be heard with headphones etc. is incorporated into
the configuration for an open-type acoustic system, even when listening with such headphones,
an open-type acoustic The sound image localization for the system is performed, and the desired
realism can not be obtained.
The opposite is also true.
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[0004]
The present invention has been made in view of the above problems of the prior art, and has at
least two sets of acoustics having different mode characteristics such as those for the open type
acoustic system and the non-open type acoustic system as described above. It is an object of the
present invention to provide a sound image control apparatus capable of preventing a sense of
reality even when switching modes (when switching the sound conversion means) when the
conversion means is used in the same configuration.
[0005]
Therefore, the configuration of the sound image control apparatus according to the present
invention includes at least two sets of acoustic conversion means having different mode
characteristics when converting musical tone signals, and the mode characteristics of these
acoustic conversion means. Operation means for performing operation for localizing the musical
tone signal at an arbitrary position according to the processing means, and switching means for
distributing the musical tone signal output from the operation means to any one of the acoustic
conversion means, Selection means for selecting whether the sound conversion means is to be
converted or not, storage means for storing plural sets of calculation processing procedures for
each mode characteristic, storing coefficients corresponding to each calculation processing
procedure, and selection of the selection means Based on the result, there is provided control
means for sending calculation processing procedures and coefficients according to the mode
characteristics from the storage means to the calculation means and for distributing signals to
the switching means. It is basically characterized in that.
[0006]
Of course, musical tone signals to be processed include digital signals (including those obtained
by AD converting analog signals) that are input, as well as being incorporated into electronic
musical instruments and game machines, etc. The tone signal may be used.
[0007]
In general, a sound source must store two readout waveforms of L and R for one tone color, and
must synthesize two tones of L and R. Therefore, the necessary storage of storage means such as
waveform ROM There is a problem that the capacity increases, and the number of simultaneously
generated tones decreases to synthesize two musical tones for one tone color.
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In the configuration of claim 3 of the present invention, in order to solve these problems, the
operation means measures in advance the input operation signal representing one timbre, based
on the given operation processing procedure and coefficient. HRTF filter processing simulating
the frequency characteristic and phase characteristic of the head related transfer function unit
and REF filter processing simulating the frequency characteristic and phase characteristic of the
reflection component measured simultaneously with the head related transfer function unit are
performed on the left and right respectively It was composition.
With such a configuration, two musical tone signals of L and R can be obtained with respect to a
musical tone signal representing one timbre, and since the musical tone signal includes a
simulated reflection component, the tone image The localization is clearer and more realistic.
[0008]
On the other hand, if the processing procedure and coefficients stored in the storage means
include a stereo enlargement processing procedure and its coefficients in addition to the
processing procedure of the filter processing, it is necessary to emphasize the difference between
L and R signals. The sense of stereo will be expanded.
[0009]
According to a fifth aspect of the present invention, in the case where one for an open sound
system and one for a non-open sound system are used as the sound conversion means, the
operator selects the sound conversion means for these sound systems. A detection means for
detecting a result is characterized in that it is used as the selection means.
Specifically, when headphones are used, the switch provided at the insertion port of the
headphone jack is the above detection means, and switching of electrical ON / OFF by its
insertion and removal is an acoustic conversion means for these acoustic systems. It becomes
possible to detect selection and non-selection.
With such a configuration, the operator does not need to operate the switch at all, and only by
attaching and detaching the headphone jack, the sound image suitable for the mode of each
system at the same time as mode change (switching of sound conversion means for other sound
systems). It becomes possible to localize to a position. In addition, it is not necessary to display
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the required mode change state every time the switch is operated.
[0010]
The control means sends the distribution signal to the switching means on the basis of the
selection result (detection result) of the selection means, and the storage means makes the
calculation processing procedure and the coefficient according to the mode characteristic from
the storage means. In order to transmit the sound image, the sound image can be localized to a
position suitable for each sound conversion means simultaneously with the mode change
(switching of the sound conversion means).
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below.
FIG. 1 is a circuit diagram showing the configuration of an embodiment of an audio apparatus to
which a sound image control apparatus according to the configuration of claim 5 is applied. In
the figure, 1 and 2 are sound conversion means, of which 1 is a first signal output means for an
open sound system using a stereo speaker system, and 2 is a second signal for a non-open sound
system using headphones. It is an output means. Further, 3 indicates an arithmetic unit, 4
indicates a switching unit, 5 indicates a detection unit, 6 indicates a storage unit, and 7 indicates
a control unit. Although the output signals actually have L and R, for simplicity, they are shown
in a single state in the drawing. Further, although the present configuration is described as an
audio device, since the basic configuration is the same, the configuration as an electronic musical
instrument will be described together in the present configuration. In this case, the input signal is
a tone signal generated by tone generation means (not shown) based on the tone of 1 designated
by the keyboard (not shown) or the like.
[0012]
The first signal output means 1 and the second signal output means 2 constituting the acoustic
conversion means have a common DA converter 11, and these are passive elements such as OP
elements, active elements such as transistors, and resistors, respectively. It consists of
Furthermore, the first signal output means 1 is provided with a pin jack or standard jack (not
shown) for connecting a stereo speaker system, and the second signal output means 2 is a
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headphone jack with a switch 50 constituting detection means 5 described later. The insertion
slot 20 is provided. In addition to these, digital signal output means (different from conversion
characteristics for these analog signals) may be provided.
[0013]
The computing means 3 is constituted by a digital signal processor (DSP), but part of the
computation may be compensated by an analog filter or the like. Then, an analog signal is AD
converted or a digital signal (or a digital signal generated from a tone generation means) input
directly as a digital signal is input, and an operation for localizing a sound image to an arbitrary
position is performed and input. Process and output the signal. In that case, the control means 7
to be described later is suitable for the mode characteristics of the sound conversion means for
an open sound system (for speaker mode) using a stereo speaker system or for a non-open sound
system (for headphone mode) using headphones. Arithmetic processing procedure and
coefficients (In this configuration, as described later, since the localization position of the sound
image is set to 30 ° in front of the listener in both modes, preset arithmetic processing
procedures and coefficients are prepared for each mode. In order to send out the calculation
processing procedure and coefficient) to the calculation means 3, the calculation means 3
performs calculation processing for localizing the sound image at an arbitrary position with
respect to the input signal based thereon. In this configuration, although the calculation
processing is performed based on the preset calculation processing procedure and coefficients,
the localization of the sound image by the instruction of the operator using the instruction means
capable of specifying the position of the three-dimensional space such as joystick In the case of
specifying the position, it is also possible to carry out the arithmetic processing based on the
arithmetic processing procedure and coefficients selected thereby.
[0014]
The switching means 4 is configured to distribute the musical tone signal outputted from the
computing means 3 to the first signal output means 1 or the second signal output means 2, and
an arbitrary configuration such as a multiplexer, a transistor, a FET or a relay is used. ing. This
switching process is performed in accordance with an instruction based on a distribution signal
of the control means 7 described later.
[0015]
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The detection means 5 corresponds to the configuration of the selection means of claim 1, and
comprises a switch 50 for the headphone jack insertion slot 20, and headphones are used for
switching electrical on / off by inserting and removing the headphone jack. It is possible to detect
whether the sound conversion means for the non-open type sound system is selected (headphone
mode) or the sound conversion means for the open type sound system using the stereo speaker
system is selected (speaker mode). The detection (selection) result is output to the I / O port 71
of the control means 7 described later.
[0016]
The storage means 6 has a ROM 60 for storing a control program of the CPU 70 of the control
means 7 described later, and a RAM 61 necessary as a working storage area at the time of
arithmetic processing of the CPU 70. RAM 61 stores a plurality of sets of operation processing
procedures (programs) necessary for the arithmetic processing of the arithmetic operation unit 3
and a table storing coefficients according to the respective operation processing procedures
(operation processing suitable for mode characteristics of the sound conversion unit for the
speaker mode A table storing procedures / coefficients and a table storing operation processing
procedures / coefficients suitable for mode characteristics of the sound conversion means for the
headphone mode are stored. Further, these arithmetic processing procedures and coefficients
stored in the RAM 61 can be obtained from an external device (not shown) (external storage
means such as a flexible magnetic disk, hard disk, CD-ROM, or other computer) via the I / O port
71. It will be transferred. In this case, an interface corresponding to these external devices must
be provided.
[0017]
The control means 7 controls the arithmetic processing of the arithmetic means 3 and sends a
distribution signal to the switching means 4. The control means 7 performs the control of the
CPU 70, and inputs the detection results of the detection means 5 and others. It has an I / O port
71 necessary for input / output to the device. The configuration of the control means 7 may be
configured by a gate array, random logic or the like in addition to the CPU 70 and the like.
[0018]
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In the sound image control apparatus used in the present audio device, the musical operation
signal corresponding to the left and right ears of the listener is calculated by the calculating
means 3 with respect to one input signal (the musical tone signal when the musical tone signal is
generated from the musical tone generation signal). To obtain two sound image control signals.
At this time, the HRTF filter processing simulating the frequency characteristic and the phase
characteristic of the head related transfer function section measured in advance on the basis of
the above-mentioned operation processing procedure and coefficient given to the input signal of
1 with respect to one input signal. And, by adopting a configuration that performs REF filtering
processing simulating the frequency characteristic and the phase characteristic of the reflection
component measured simultaneously with the head related transfer function unit, the tone signal
representing one tone color is L. And R tone signals are obtained. In addition, since the tone
signal contains simulated reflection components, the localization of the sound image becomes
clear, and it becomes more realistic.
[0019]
The filtering process of the computing means 3 simulates the example of the impulse response of
each of the measured left and right ears shown in FIGS. 2A and 2B, and a pseudo stereo effect is
obtained by this process. In this example, the sound source of the impulse is located to the left of
the front of the head. In this operation means 3, an IIR filter simulating the frequency
characteristics and phase characteristics of the time TLH portion (head transfer function portion)
of the measured impulse response is used as the HRTF filter for the left ear, and the measured
impulse response An IIR filter simulating the frequency characteristics and phase characteristics
of the time TRH portion (head-related transfer function portion) is used as the HRTF filter for the
right ear. Furthermore, in the actual impulse response, there are echoes in addition to this, and
that amount must be reproduced as well. Therefore, IIR filters that simulate the frequency
characteristics and phase characteristics of the time TLR (for the left ear) and the TRR (for the
right ear) of the measured impulse response (reflector) are used as the left and right REF filters.
These filter processes are implemented by the DSP that constitutes the computing means 3. Also,
the HRTF filter requires separate filters for the right ear and for the left ear for one localization
position, and in this configuration, the processing flow of the computing means 3 is
schematically shown in FIG. In order to localize the sound image at two different points (position
a and position b), a total of four HRTF filters are required. Similarly, four REF filters are required.
[0020]
FIG. 4 shows an actual processing circuit configuration for localizing the sound image to the
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position a in the processing flow of FIG. 3 above, using one delay unit 30 having a plurality of
delay tap outputs, and The HRTF filters 31a and 31b for the right ear and the right ear are
combined with the REF filters 32a and 32b, and the amplifier is further multiplied by a
coefficient calculated from the amplitudes of peak points indicated by GL0 to GLn and GR0 to
GRn in the drawing. And adders 33a to 33d. TL1 to TLn and TR1 to TRn in the same figure
correspond to each time shown in FIG. 2, TL0 to TLn are delay tap outputs for processing for the
left ear, and TR0 to TRn are delay tap outputs for processing for the right ear It is. Further, TL0
and TR0 have 0 as a reference point, and TL1, TL2, TLn, TR1, TR2, and TRn are the times from
the peak of the head related transfer function part to the relatively high peak of the reflection
part. Moreover, TRO-TL0 is a binaural time difference. The delay unit 30 can be constituted by a
RAM delay unit, and the output units TL0 to TLn and TR0 to TRn output signals obtained by
respectively delaying the input signals by a predetermined time. The coefficients used for the
above-mentioned filter processing, the time information between the taps and the coefficients of
the amplitude are stored in the storage means 6.
[0021]
Further, in the present embodiment, in the case of the speaker mode, as shown in FIG. 3, stereo
enlargement processing is performed by the calculating means 3. That is, the processing
procedure and coefficients stored in the storage means 6 include the stereo enlargement
processing procedure and the coefficients thereof, which are read into the DSP in the speaker
mode, and the processing is carried out. In this configuration, as shown in FIG. 5, the difference
signal SD of the input L and R is determined by the operation unit 34, and the low-pass
component SF is extracted by the first-order low-pass filter 35. The difference between the
signals of LR is enhanced by adding to and subtracting from the R signal in the operation unit 37,
thereby expanding the sense of stereo. In this configuration, the signal SF extracted from the
first-order low-pass filter 35 is delayed by the delay unit 38 in order to correct the arrival time of
the sound from the speaker to the ear.
[0022]
The operation of the above embodiment will be described based on the flowchart of FIG. When
the apparatus is powered on, the program stored in the ROM 60 of the storage unit 6 is read into
the CPU 70, and the program is started. Then, the CPU 70 checks, via the I / O port 71, whether
the switch 50 of the headphone jack insertion port 20 is ON or OFF (S1). Here, it is determined
that the headphone jack is attached when the switch 50 is ON, and is removed when the switch
50 is OFF.
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[0023]
If the switch 50 of the headphone jack insertion slot 20 is ON, the CPU 70 loads the operation
processing procedure (only sound image localization processing) for the headphone mode to the
DSP of the operation means 3 and localization of the preset sound image In order to localize the
sound image to the position (30 °), the coefficients for localizing to the front 30 ° of the
listener and the coefficients for localizing to -30 ° are transferred. At the same time, the
distribution signal to the second output means 2 is outputted to the switching means 4 (S2).
Therefore, the input digital signal (a digital signal obtained by AD conversion in the case of an
analog signal) is sent to the arithmetic means 3, and the DSP performs arithmetic processing for
the headphone mode by the DSP, and the second output The sound image is output to the means
2 and output from the headphones in a state where the sound image is localized at each position
of 30 ° and -30 °.
[0024]
If the switch 50 is OFF, the CPU 70 loads the operation procedure (sound image localization
processing and stereo enlargement processing) for the speaker mode to the DSP of the
calculation means 3 and also the localization position of the preset sound image ( In order to
localize the sound image to 30 °), transfer the coefficients for localizing to the front 30 ° of the
listener and the coefficients for localizing to -30 °. At the same time, the distribution signal to
the first output means 1 is outputted to the switching means 4 (S3). Therefore, the input digital
signal is sent to the computing means 3, the DSP performs a computing process for the speaker
mode by the DSP, and the signal is outputted to the first output means 1 to the 30 ° and -30 °
positions. The sound image is output from the speaker in a state of being localized. Note that only
a part of the calculation processing procedure and the coefficients transferred at the time of
mode switching by the switch 50 may be changed. By doing so, the transfer speed will be much
faster.
[0025]
Next, through the I / O port 71, the CPU 70 again checks whether the switch 50 of the
headphone jack insertion slot 20 is ON or OFF (S4). If there is a change in the state of the switch
50, the CPU 70 transfers the operation processing procedure for the headphone mode and the
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coefficients used for the processing to the DSP of the operation means 3 if the switch 50 is in the
ON state. The distribution signal to the second output unit 2 is output to the switching unit 4. On
the other hand, if the switch 50 is in the OFF state, the processing procedure for the speaker
mode and the coefficients used for the processing are transferred to the DSP, and the distribution
signal to the first output means 1 is sent to the switching means 4 Output.
[0026]
As described above, at the time of mode change, the calculation processing procedure and
coefficients suitable for each mode characteristic are sent to perform the calculation processing
of the input signal, so that a sufficient sense of localization of the sound image can be obtained in
both the speaker mode and the headphone mode. Become. In addition, since the control means 7
automatically performs mode change by the switching means 5 and change of the arithmetic
processing in the arithmetic means 3 by detecting the insertion and removal of the headphone
jack as described above, the operator performs special switch operation Without changing the
mode, it is possible to change modes for the speaker mode and the headphone mode, and at the
same time to localize the sound image to a position suitable for each mode. Furthermore, it is not
necessary to display the required mode change state every time the switch is operated.
[0027]
Moreover, in the present configuration, it is possible to obtain a comfortable pseudo-stereo effect
that feels natural only by inputting one signal. The signal can also be generated by the tone
generation means and used as an input signal, but in such a configuration, a stereo effect with a
natural feel can be obtained simply by inputting one tone signal. There is no need to store the
readout waveform corresponding to each R, nor the need to synthesize two musical tones for one
tone color, and the number of simultaneous sounds does not decrease.
[0028]
In this configuration, the sound image localization position is preset at the position of 30 °, but
this localization position can be set to an arbitrary position by separately providing an instruction
unit. In this case, it is necessary to store coefficients corresponding to the angle to be changed.
The instruction means may be provided with an effect depth dial, and may have a function
capable of changing and mixing the mix balance of the original sound and the sound after
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calculation according to the amount of change. Of course, mixing with the original sound may be
performed on analog or digital.
[0029]
Furthermore, the following configuration can be added to the configuration of the above
embodiment. When the AD converter 10 and the DA converter 11 are provided before and after
the arithmetic means 3 of FIG. 1, as shown in FIG. The low pass filter 13 is provided at the
subsequent stage of the circuit. With such a configuration, white noise generated from each of
the converters 10 and 11 when performing AD conversion-signal processing-DA conversion can
be reduced, and high-quality sound can be obtained by enhancing the calculation accuracy of the
high-frequency DSP. Become. That is, the high-pass filter 12 uses a filter with RIAA recording
characteristics or characteristics similar to it, and the low-pass filter 13 uses a filter with RIAA
reproduction characteristics or characteristics similar to that to input analog signals. The RIAA
recording characteristics raise the high frequency band in advance and lower the low frequency
band, and after signal processing, lower the high frequency band in the RIAA playback
characteristics to raise the low frequency band, thereby for frequencies above 1 KHz that are
easy to hear as auditory noise It can remove up to 20 dB of noise. Since the RIAA recording
characteristic is originally intended to make the tone signal as uniform as possible on the
frequency axis, the amplitude of the waveform generally dependent on the fundamental wave
(low frequency band) is determined by the RIAA recording characteristic. The fundamental wave
is compressed and the harmonics are expanded, so that the spectrum is equalized. As a result, the
calculation accuracy of the high frequency characteristic is improved, which is extremely
advantageous in sound quality.
[0030]
The high pass filter 12 has a circuit configuration as shown in FIG. 8 and the low pass filter 13
has a circuit configuration as shown in FIG. 9 (time constant T1 = 4840 μs, time constant T2 =
396 μs, time constant T3 = 84) The noise was designed to be approximately 0 dB at 1 KHz (6
μs), and the noise caused by pianissimo was almost inaudible.
[0031]
Further, in the present audio device, as shown in the block diagram of FIG. 10, the power supply
can be completely shut off by turning on / off the power switch of the audio device using the
CPU 70 of the control means 7 Can also be used separately.
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In this configuration, when the push switch 72 is pressed in the power-off state, the power switch
73 is closed. As a result, the CPU 70 operates, and the CPU 70F keeps outputting a signal (power
ON signal) to close the power switch 73. On the other hand, when the push switch 72 is pressed
from the power on state, the voltage input to the voltage subtractor 74 rises from the voltage of
the CPU 70 (for example 5 V) to the power supply voltage (for example 12 V). When the voltage
rises to the power supply voltage, the output voltage of the voltage subtractor 74 rises from 0 V
to the voltage of the CPU 70 (for example, 5 V). The change is used as a power OFF signal, and
the CPU 70 turns off the power.
[0032]
FIG. 11 shows a control flow in the CPU 70 configured as described above. First, when the push
switch 72 is turned on, the program starts and the power control signal is activated (S5, power
on signal output). Then, the processing routine other than the power supply is performed (S6).
Thereafter, the CPU 70 detects a power on signal event (S7), and if it is determined in S8 that
there is no event of power on signal, the process returns to S5, and if it is determined that there
is an event, the power on signal is next It is determined whether it is active (S9). If the signal is
active, the PowerOFF flag is set (S10), and the process returns to S5. On the other hand, if the
signal is not active, it is determined whether the PowerOFF flag is set (S11), and if not, the
process returns to S5. If the flag is set, the power control signal is deactivated (S12, the power is
turned off), and the process is ended.
[0033]
The actual device configuration of the circuit block diagram configuration of FIG. 10 can be
realized by the configuration shown in FIG.
[0034]
According to the configuration of the present invention described above in detail, since the
processing procedure and coefficients suitable for each mode characteristic are sent at the time
of mode change to perform the processing of the input signal, localization in any mode is
sufficient. You will be able to get a feeling.
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Further, as described in claim 5, since the mode change and the change of the arithmetic
processing suitable for the mode characteristic can be automatically performed by the detection
by the detection means, the operator does not need to operate the special switch. Even at the
same time as mode change can be performed, localization to a sound image position suitable for
each mode can be achieved. Furthermore, when the switch is operated, it is not necessary to
display the required mode change state one by one. Furthermore, according to the configuration
of claim 3, since the arithmetic means performs the HRTF filter process and the REF filter
process for each of the left and right based on the above-mentioned operation procedure and
coefficients given, only one signal is input A natural and comfortable pseudo-stereo effect will be
obtained. In an electronic musical instrument or the like, a musical tone signal can be generated
by the musical tone generating means and used as an input signal. However, in such a
configuration, a stereo effect with a natural feeling is obtained simply by inputting one musical
tone signal. Therefore, there is no need to store the readout waveform corresponding to each of L
and R, and there is no need to synthesize two musical tones for one tone color, and the number
of simultaneous sounds does not decrease.
[0035]
Brief description of the drawings
[0036]
1 is a circuit diagram showing a configuration of an embodiment of a sound image control
apparatus according to the invention of FIG.
[0037]
2 is a waveform diagram showing an example of the measured impulse response of the left and
right ears measured.
[0038]
3 is a schematic diagram of the processing flow of the computing means.
[0039]
4 is a circuit diagram showing an actual circuit configuration of the processing configuration of
sound image localization to the position a.
[0040]
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5 is a schematic diagram of a processing flow of stereo enlargement processing performed in the
case of the speaker mode.
[0041]
6 is a flowchart illustrating the operation of the configuration of the present embodiment.
[0042]
7 is a schematic diagram showing a processing flow of a configuration to reduce the white noise
generated from each converter when performing AD conversion-signal processing-DA
conversion.
[0043]
<Figure 8> It is the schematic which shows the circuit constitution of the high pass filter in the
above-mentioned constitution.
[0044]
FIG. 9 is a circuit diagram showing a circuit configuration of the low pass filter in the above
configuration.
[0045]
10 is a block diagram showing a configuration added with a configuration that can completely
shut off the power supply by performing power switch ON / OFF of the audio equipment using
the CPU.
[0046]
11 is a flowchart showing a control flow in the CPU of the above configuration.
[0047]
12 is a circuit diagram showing an actual circuit configuration of the above configuration.
[0048]
Explanation of sign
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[0049]
1, 2 Output means 3 Calculation means 4 Switching means 5 Detection means 6 Storage means 7
Control means 20 Headphone jack insertion slot 50 switch 60 ROM 61 RAM 70 CPU
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