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JP2008085412

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DESCRIPTION JP2008085412
PROBLEM TO BE SOLVED: To provide an audio apparatus capable of obtaining a low-pitched
feeling even with a small diameter speaker. SOLUTION: A high pass filter 2 for extracting a signal
component S2 having a resonance frequency f0 or more of a speaker 5 from an audio signal S1
is provided. A band pass filter 21 for extracting a low frequency component S21 whose
frequency is included in a band f0 / 2 to f1 / 2 from the audio signal S1, and a low band whose
frequency is included in a band f0 / 4 to f1 / 4 from an audio signal S1 A band pass filter 41 for
taking out the component S41 is provided. A pitch shift circuit 22 for doubling the output of the
band pass filter 21 and a pitch shift circuit 42 for quadrupling the output of the band pass filter
41 are provided. An addition circuit 3 is provided which adds the output of the high pass filter 2
and the outputs of the pitch shift circuits 22 and 42 at a predetermined ratio. The output signal
S3 of the adder circuit 3 is supplied to the speaker 5. [Selected figure] Figure 1
Audio playback device
[0001]
The present invention relates to an audio reproduction apparatus.
[0002]
In so-called mini components and thin televisions, etc., a speaker with a small aperture is used,
and the volume of a speaker box (enclosure) housing the speaker tends to be small.
08-05-2019
1
For this reason, the resonance frequency f0 of the speaker is increased to about 100 Hz or more.
[0003]
Generally, when an audio signal at a resonance frequency f0 or less is supplied to the speaker,
the output sound pressure of the fundamental wave component decreases as the frequency
decreases, and the distortion component (harmonic component) rapidly increases. Tend.
[0004]
Therefore, in an audio device using a speaker with a small aperture as described above, bass at a
resonance frequency f0 or less of the speaker can not be reproduced sufficiently.
[0005]
By the way, the sound of an instrument is composed of a fundamental sound and its overtones,
and the ratio determines the timbre.
And, even if the fundamental sound is not output, it is psychoacoustically demonstrated that the
human auditory sense is perceived as if the basic sound is output if the overtone is output.
[0006]
Therefore, an audio device has been considered that can obtain a bass feeling by using such
perceptual characteristics.
FIG. 11 shows an example of such an audio apparatus, in which reference numeral 5 is a speaker
targeted for improvement of the bass feeling.
[0007]
Then, the audio signal S1 is supplied to the high pass filter 2 through the input terminal 1, and as
shown in FIG. 12A, the middle high frequency component S2 higher than the resonance
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2
frequency f0 of the speaker 5 is extracted. Supplied to Also, the audio signal S1 at the input
terminal 1 is supplied to the band pass filter 7, and as shown in FIG. 12B, the low frequency
component S7 having a frequency of f0 / 2 to f0 is extracted, and this low frequency component
S7 is a pitch shift circuit Supplied to 8
[0008]
The pitch shift circuit 8 doubles the frequency of the low frequency component S7 supplied
thereto, and therefore, as shown in FIG. 12C, the pitch shift circuit 8 has a frequency of f0 to 2f0.
The harmonic component S8 is output.
[0009]
Then, the harmonic component S8 is supplied to the addition circuit 3 and added to the middle
high frequency component S2, and the addition circuit 3 generates an audio signal S3 in which
the harmonic component S8 of the low frequency component S7 is enhanced as shown in FIG.
12D. The signal S 3 is taken out and supplied to the speaker 5 through the power amplifier 4.
Therefore, the speaker 5 outputs a sound output of a frequency characteristic as shown in FIG.
12D, that is, a sound in which the overtone component S8 of the low frequency component S7 is
enhanced.
[0010]
In this case, although the low-frequency component S7 does not output the sound of the lowfrequency component S7 from the speaker 5, the low-frequency component S7 corresponds to
the basic sound component and the sound of the overtone component S8 is output as described
above. The listener is perceived as if the sound of the low-pass component S7 is output, and
therefore, even if the speaker 5 has a small aperture, a low-pitched feeling can be obtained.
[0011]
Generally, when the low-frequency component S7 is harmonically processed to generate the
harmonic component S5, it is considered that the sense of discomfort does not occur if the
frequency of the harmonic component S5 is about 200 Hz or less.
[0012]
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Examples of prior art documents are as follows.
Unexamined-Japanese-Patent No. 8-213862 gazette
[0013]
However, in the case of the above-described audio reproduction apparatus, an appropriate bass
feeling may not be obtained depending on the frequency of the low frequency component S7.
That is, it is assumed that the reproduction band (frequency characteristic) of the speaker 5 is
shown by the curve F5 in FIG. 13A, and at this time, the resonance frequency f0 is 100 Hz.
[0014]
Then, for example, as shown in FIG. 13A, assuming that the frequency of the low frequency
component S7 is 60 Hz, the frequency of the overtone component S8 is 120 Hz as also shown in
FIG. 13A. Then, if the frequency of the harmonic component S8 is 120 Hz, this is included in the
reproduction band F5 of the speaker 5, so it is possible to feel the low frequency component S7
due to the harmonic component S8 as described above.
[0015]
However, for example, as shown in FIG. 13B, assuming that the frequency of the low frequency
component S7 is 35 Hz, the frequency of the overtone component S8 is 70 Hz as also shown in
FIG. 13B. Then, if the frequency of the harmonic component S8 is 70 Hz, this is not included in
the reproduction band F5 of the speaker 5, so that the acoustic component is not output.
Therefore, the low frequency component S7 is obtained by the harmonic component S8. It is not
possible. Rather, since the harmonic component S8 of a frequency lower than the resonance
frequency f0 is supplied to the speaker 5, distorted sound is output from the speaker 5.
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[0016]
Further, for example, as shown in FIG. 13C, assuming that the resonance frequency f0 of the
speaker 5 is 120 Hz and the frequency of the low frequency component S7 is 110 Hz, the
frequency of the overtone component S8 is also shown in FIG. 13C. It will be 220 Hz. Then, since
the frequency 220 Hz of the harmonic component S8 is included in the reproduction band F5 of
the speaker 5, the acoustic component is output. However, as described above, the upper limit of
the frequency at which the harmonic component S8 does not cause discomfort is about 200 Hz,
and in this case, the frequency 220 Hz of the harmonic component S8 exceeds the upper limit. I
feel
[0017]
The present invention is intended to solve the above problems.
[0018]
In the present invention, N = 2 <n> where n is an integer from 1 to 6 f1: When the fundamental
wave component of a certain signal is multiplied, the resulting multiplied wave component is a
frequency that does not cause auditory discomfort. When the high-pass filter that extracts the
mid-high frequency component of the speaker's resonant frequency f0 or more from the audio
signal, and n band-pass paths that extract low-frequency components whose frequency is
included in the frequency band f0 / N to f1 / N from the audio signal A filter, n pitch shift circuits
that multiply each of the outputs of the n band pass filters by N, an output of the high pass filter,
and an output of the n pitch shift circuits are added at a predetermined ratio An audio
reproduction apparatus configured to supply the output signal of the addition circuit to the
speaker.
[0019]
According to the present invention, when the frequency of the low frequency component of the
audio signal is lower than the resonance frequency f0 of the speaker, the sound of the harmonic
component of the low frequency component is output. You can get
In addition, when the low frequency component is multiplied, the overtone component of the
multiplication result is multiplied so that it falls within the band between the resonance
frequency f0 of the speaker and the upper limit frequency f1. There is no
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[0020]
[1] First Example FIG. 1 shows a first example of the configuration according to the present
invention, in which reference numeral 5 is a speaker with a small aperture, which is an object of
improvement in bass.
Here, f 0: resonant frequency of the speaker 5. In this example, around 100 Hz or less. f1: When
the fundamental wave component of a certain signal is multiplied, a frequency (a frequency of
the signal of the multiplication result) that does not cause an auditory sense of discomfort in the
multiplied wave component as a result thereof. Generally around 200 Hz. とする。 In this
example, f0 = f1 / 2 (or f0 ≦ f1 / 2). In the case of two-channel stereo or multi-channel stereo,
each channel can be configured as shown in FIG.
[0021]
Then, the audio signal S1 is supplied to the high pass filter 2 through the input terminal 1, and as
shown by the solid line in FIG. 2A, the mid-high band component S2 higher than the resonance
frequency f0 of the speaker 5 is extracted and this mid-high band component S2 is added It is
supplied to the circuit 3. Further, a band pass filter 11 having a pass band of frequencies f0 to f1
(100 Hz to 200 Hz in this example) is provided, and the audio signal S1 from the input terminal
1 is supplied to the band pass filter 11 and a broken line is shown in FIG. As shown, the low band
component S11 having a frequency band of f0 to f1 is extracted, and this low band component
S11 is supplied to the adding circuit 3 through the attenuator circuit 13.
[0022]
Furthermore, a band pass filter 21 is provided with a pass band of frequencies f0 / 2 to f1 / 2, 50
Hz to 100 Hz in this example, and the audio signal S1 from the input terminal 1 is supplied to the
band pass filter 21. As shown in FIG. 2B, a low frequency component S21 having a frequency of
f0 / 2 to f1 / 2 is extracted, and this low frequency component S21 is supplied to the pitch shift
circuit 22.
[0023]
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The pitch shift circuit 22 doubles the frequency of the low-frequency component S21 supplied to
the pitch shift circuit 22 as described later, and therefore, as shown in FIG. 2C, the pitch shift
circuit 22 doubles it. The harmonic component S22 having a frequency twice as high, that is, the
harmonic component S22 having a frequency of f0 to f1 is output.
The double harmonic component S22 is supplied to the addition circuit 3 through the attenuator
circuit 23.
[0024]
Further, a bandpass filter 41 is provided whose passband is a frequency f0 / 4 to f1 / 4, in this
example 25 Hz to 50 Hz, and the audio signal S1 from the input terminal 1 is supplied to the
bandpass filter 41. As indicated by a solid line in FIG. 2D, a low frequency component S41 having
a frequency of f0 / 4 to f1 / 4 is extracted, and this low frequency component S41 is supplied to
the pitch shift circuit 42.
[0025]
The pitch shift circuit 42 multiplies the frequency of the low-frequency component S41 supplied
thereto by four times, and therefore, from the pitch shift circuit 42, the frequency of four times
as shown by the broken line in FIG. 2D. The harmonic component S42, that is, the harmonic
component S42 having a frequency of f0 to f1 is output.
The quadruple harmonic component S 42 is also supplied to the adder circuit 3 through the
attenuator circuit 43.
[0026]
Thus, as shown in FIG. 2E, from the adding circuit 3, the low-frequency component S11, the
double harmonic component S22, and the quadruple harmonic component S42 are added to the
middle high frequency component S2, and the attenuator circuits 13, 23, The audio signal S3
added at a predetermined rate is taken out by 43. Then, the addition signal S 3 is supplied to the
speaker 5 through the power amplifier 4.
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[0027]
According to such a configuration, when the audio signal S1 is supplied to the input terminal 1,
the pitch shift circuits 22 and 42 form the harmonic component S22 or S42 having a frequency
twice or four times that of the low frequency component S21 or S41. And this is added to the
audio signal S1. Therefore, the audio signal S1 is an audio signal S3 having a frequency
characteristic as shown in FIG. 2E, and this signal S3 is supplied to the speaker 5.
[0028]
At this time, although the sound of the fundamental sound component having the resonance
frequency f0 or less is hardly output from the speaker 5, since the sounds of the harmonic
components S22 and S42 are output, the listener has the sound having the resonance frequency
f0 or less as described above. It can be perceived as if it is being output, and therefore, even if the
speaker 5 has a small aperture, it can obtain a bass feeling.
[0029]
Then, in this case, for example, as shown in FIG. 3A, if the frequency of the low frequency
component S21 (S41) is 35 Hz, the harmonic overtone component S22 (indicated by a broken
line) having a doubled frequency is formed from this low frequency component S21. Also, its
frequency is 70 Hz and can not be reproduced by the speaker 5 (this is the same as in FIG. 13B).
[0030]
However, in the apparatus of FIG. 1, if the frequency of the low frequency component S21 is 35
Hz, this low frequency component S21, ie, the low frequency component S41 is supplied to the
pitch shift circuit 42 through the band pass filter 41 and quadrupled. A harmonic component
S42 (shown by a solid line) having a frequency of 140 Hz is formed, and this harmonic
component S42 is supplied to the adding circuit 3.
Therefore, even if the frequency of the low frequency component S21 is 35 Hz, a bass feeling
corresponding to the low frequency component S21 can be obtained by the harmonic overtone
component S42 having a frequency four times that of the low frequency component S21.
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[0031]
For example, as shown in FIG. 3B, if the frequency of the low frequency component S41 (S21) is
60 Hz, then if the harmonic overtone component S42 (shown by a broken line) having a
frequency four times that of the low frequency component S41 is Since the frequency is 240 Hz
and exceeds the upper limit frequency f1 (200200 Hz) when adding harmonics, the harmonics
component S42 may cause discomfort when supplied to the speaker 5 (this is the case with FIG.
13C). As well).
[0032]
However, in the apparatus of FIG. 1, if the frequency of the low frequency component S41 is 60
Hz, the low frequency component S41, ie, the low frequency component S21, is supplied to the
pitch shift circuit 22 through the band pass filter 21 and doubled. The harmonic component S22
(shown by a solid line) having a frequency of 120 Hz is supplied to the adding circuit 3.
Therefore, even if the frequency of the low frequency component S41 is 60 Hz, it is possible to
obtain a bass feeling corresponding to the low frequency component S41 by the harmonic
component S22 of the frequency twice as high.
[0033]
Further, as shown in FIGS. 2A and 2E, the low frequency component S11 included in the original
input audio signal S1 is also enhanced, so that the bass can be made natural.
[0034]
[2] Second Example FIG. 4 shows a second structural example of the present invention. In this
example, even when f0> f1 / 2, the bass can be effectively obtained. It is.
That is, as in the apparatus of FIG. 1, the middle high frequency component S 2 and the low
frequency component S 11 are extracted from the input audio signal S 1 and supplied to the
addition circuit 3.
[0035]
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9
Also, the input audio signal S1 is supplied to the band pass filter 21, and as indicated by a broken
line in FIG. 5A, a low frequency component S21 having a frequency of f0 / 2 to f1 / 2 is
extracted, and this low frequency component S21 has a pitch It is supplied to the shift circuit 22,
and as shown by the solid line in FIG. 2A, the pitch shift circuit 22 outputs an overtone
component S22 having a double frequency, that is, an overtone component S22 having a
frequency of f0 to f1.
Then, the double harmonic component S22 is supplied to the addition circuit 62 through the
attenuator circuit 23.
[0036]
Further, the input audio signal S1 is supplied to the band pass filter 41, and as indicated by a
broken line in FIG. 5A, a low frequency component S41 having a frequency of f0 / 4 to f1 / 4 is
extracted, and this low frequency component S41 has a pitch As shown by the solid line in FIG.
2A, the pitch shift circuit 42 outputs a harmonic overtone component S42 having a frequency of
4 times, that is, a harmonic overtone component S42 having a frequency of f0 to f1. Then, the
fourfold harmonic component S 42 is supplied to the addition circuit 62 through the attenuator
circuit 43.
[0037]
Then, as shown in FIG. 5B, the addition circuit 62 takes out the addition signal S62 of the double
harmonic component S22 and the quadruple harmonic component S42, and this addition signal
S62 is supplied to the low pass filter 63. Ru. The low pass filter 63 has a frequency characteristic
shown, for example, by a curve F63 in FIG. 5C, that is, has a resonance frequency f0 as a cutoff
frequency and has an upper frequency limit f1 which substantially cuts off an input signal
component. is there.
[0038]
Therefore, the low-pass filter 63 outputs the doubled and quadrupled harmonic component S63
08-05-2019
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(hatched portion) of the addition signal S62 without giving a sense of incongruity. Then, the
harmonic component S63 is supplied to the adding circuit 3, and the output signal S3 of the
adding circuit 3 is supplied to the speaker 5 through the power amplifier 4.
[0039]
According to such a configuration, as in the apparatus of FIG. 1, the pitch shift circuits 22 and 42
form the harmonic component S22 or S42 having a frequency twice or four times that of the low
frequency component S21 or S41. As described above, the speaker 5 is perceived as if a sound
having a resonance frequency f 0 or less is output, and therefore, even if the speaker 5 has a
small aperture, it can obtain a bass feeling. it can.
[0040]
Then, in this case, the harmonic component S63 of 2 times and 4 times is added to the middle
high frequency component S2 in the adding circuit 3, but the level of the harmonic component
S63 is reduced by the low pass filter 63 as it approaches the upper limit frequency f1. Therefore,
even if the overtone component S63 includes a signal component exceeding the upper limit
frequency f1, for example, the sense of discomfort can be suppressed.
As a result, even if f0> f1 / 2, for example, it is possible to obtain a bass feeling without giving a
sense of incongruity.
[0041]
[3] Third Example FIG. 6 shows a third example of the configuration of the present invention, and
an audio signal S1 is supplied to the high pass filter 2 through the input terminal 1 and the
speaker 5 is A mid-high frequency component S2 higher than the resonance frequency f0 is
extracted, and the mid-high frequency component S2 is supplied to the adding circuit 3. Also, the
audio signal S1 from the input terminal 1 is supplied to the low pass filter 10 whose passband is
the frequency f1 or less, in this example, 200 Hz or less, and the low frequency component S10
having the upper frequency f1 or less is extracted. The component S10 is supplied to the adding
circuit 3 through the attenuator circuit 13 and is added to the middle / high frequency
component S2 at a predetermined ratio.
08-05-2019
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[0042]
Further, band pass filters 21 and 41 similar to the apparatus of FIG. 1 and pitch shift circuits 22
and 42 form double and quadruple harmonic components S22 and S42, and these harmonic
components S22 and S42 are attenuator circuits 23 and 43. Are supplied to the addition circuit 3
and added to the middle / high frequency component S2 at a predetermined ratio.
[0043]
Thus, as shown in FIG. 7A, from the adding circuit 3, as shown in FIG. 7A, the low-frequency
component S11, the double harmonic component S22, and the quadruple harmonic component
S42 are added to the middle frequency component S2, and the attenuator circuits 13, 23, The
audio signal S3 added at a predetermined rate is taken out by 43.
[0044]
Then, the addition signal S3 is supplied to the low pass cut filter 6, and as shown in FIG. 7B, a
heavy low pass component harmful to the small diameter speaker 5 in the audio signal S3, that
is, supplied to the speaker 5. When the low-frequency component such that a large amount of
distortion component (harmonic component) is output is taken as an audio signal S6 from which
a normal low frequency sound is not output, and this audio signal S6 is output to the speaker 5
through the power amplifier 4 Supplied.
[0045]
According to such a configuration, although the sound of the low frequency component S11 is
hardly output from the speaker 5, the sounds of the harmonic components S22 and S42 of the
low frequency component S11 are output, so as described above, The sound of the low-frequency
component S11 is perceived as if it is being output, and therefore, even if the speaker 5 has a
small aperture, a bass feeling can be obtained.
[0046]
Further, as shown in FIG. 7B, the low frequency component S11 is also left to the audio signal S6
to a certain extent, so that the bass feeling can be made natural.
At this time, since the low-frequency cut filter 6 eliminates the low-frequency component S11
which is harmful to the small-aperture speaker 5 of the low-frequency component S11, the
distortion component ( A large amount of harmonic components is not output.
08-05-2019
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[0047]
[4] An example of the pitch shift circuits 22 and 42 The overtone components S22 and S42
having a frequency twice or four times the low frequency components S21 and S41 can be
formed, for example, by a method as shown in FIG.
That is, as shown in FIG. 8A, it is assumed that digital data DA that can be D / A converted in one
cycle of the sine wave signal SA is stored in the memory.
The symbol ● indicates the sample point.
The period TA is one cycle period of the sine wave signal SA, and the period 1 / fc is one sample
period.
[0048]
Then, when the digital data DA is read out from the memory, one cycle of the sine wave signal SA
can be obtained in the period TA by reading out one sample at a time at a clock frequency fc
equal to that at the time of writing.
[0049]
When digital data DA is read from memory, as shown in FIG. 8B, it is thinned out at a clock
frequency fc equal to that at the time of writing and is read out at a rate of 1 for every 2
addresses. Two cycles of a sine wave signal SB having a frequency twice that of the sine wave
signal SA can be obtained at TA.
That is, the harmonic component SB having a frequency twice that of the sine wave signal SA can
be obtained in the period TA.
[0050]
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13
Furthermore, when reading digital data DA from the memory, as shown in FIG. 8C, while thinning
out and reading at a rate of 1 for every 4 addresses at a clock frequency fc equal to the time of
writing, and repeating the reading four times, Four cycles of a sine wave signal SC having a
frequency four times that of the sine wave signal SA can be obtained at TA. That is, the harmonic
component SC having a frequency four times that of the sine wave signal SA can be obtained in
the period TA.
[0051]
Therefore, the pitch shift circuit 22 (and 42) can be configured, for example, as shown in FIG.
That is, in FIG. 9, reference numeral 22M indicates a memory circuit which is configured by, for
example, a ring buffer and has an address (capacity) of a substantially sufficient size. Also, it is
assumed that the low-frequency component S21 is, for example, a waveform as shown in FIG.
10A, a signal obtained by A / D converting this is digital data D21, and its sampling frequency
(clock frequency) is fc.
[0052]
Further, a point in time when the polarity of the digital data D21 (low range component S21)
inverts, for example, from negative to positive is taken as time tx. In addition, a period from a
certain time point tx to the next time point tx, that is, one cycle period of the low-frequency
component S21 is a period Tx.
[0053]
Then, in FIG. 9, the digital data D21 is supplied to the memory circuit 22M through the input
terminal 22A, and as shown in FIG. 10A, the digital data D21 is sequentially written in each
address of the memory circuit 22M every one sample. Go. Therefore, the period Tx in FIG. 10
corresponds to the period TA in FIG. 8, and FIG. 10A corresponds to FIG. 8A.
[0054]
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14
At the same time as this writing, the digital data D21 written to the memory 22 is read out. In
FIG. 10, for the sake of simplicity, it is assumed that the period Tx on the write side and the
period Tx on the read side are simultaneous.
[0055]
The reading from the memory 22 is executed in the same manner as in FIG. 8B, that is, it is read
by thinning out the ratio of the first address to the second address at the clock frequency fc equal
to that at the time of writing. In addition, the reading is repeated twice in the period Tx.
Therefore, if the read out digital data D22 is D / A converted, it is possible to obtain the harmonic
component S22 having a frequency twice that of the original low frequency component S21.
[0056]
Furthermore, the low frequency component S41 is also A / D converted and written to the
memory in the same way, and if it is read as in FIG. 8C, that is, the clock frequency fc is equal to
that at the time of writing. If thinning out and reading out are repeated four times in the period
Tx, when the read out digital data is D / A converted, it is possible to obtain the harmonic
component S42 having a frequency four times that of the original low frequency component S41.
.
[0057]
[4] Summary According to the above-described apparatus, even if the frequency of the low
frequency component is lower than the resonance frequency f0 of the speaker 5, the pitch shift
circuits 22 and 42 cause the harmonic component S22 of a frequency higher than the resonance
frequency f0 of the speaker 5; Since S42 is formed, and this is added to the middle high
frequency component S2 and supplied to the speaker 5, a bass feeling can be obtained even if the
diameter of the speaker 5 is small.
[0058]
Also, when the low frequency component is multiplied, the harmonics component of the
multiplication result is doubled or quadrupled so that it falls within the band between the
resonance frequency f0 of the speaker 5 and the upper limit frequency f1. Does not cause
discomfort.
08-05-2019
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[0059]
Furthermore, as shown in FIG. 7B, the original low-frequency component S11 is also left to the
audio signal S6 to a certain extent, so that the bass can be made natural.
At this time, the heavy low band component harmful to the small diameter speaker 5 among the
low band component S11 is removed by the low band cut filter 6, so a large amount of distortion
is generated although a normal low sound is not output. There is no such thing as being output
to
[0060]
Also, for example, the harmonic component of the frequency of 3 times is not in an octave
relation to the original fundamental sound component, and thus gives a sense of discomfort, but
the harmonic component of the frequency of 2 or 4 times is the original basic The frequency
component is higher by one octave or two octaves with respect to the wave component, and the
reproduced sound does not have a sense of discomfort.
[0061]
[5] Others In the above, the signal system from the input audio signal S1 to the output audio
signal S6 is actually realized by digital processing using a DSP or dedicated hardware, so for
example, a band pass filter 21 and the pitch shift circuit 22 can share a memory, and the band
pass filter 21 and the band pass filter 41 can share a memory.
For example, when one cycle's worth of digital data is processed by the band pass filter 21 and
the processing result is supplied to the pitch shift circuit 22, the buffer memory can be shared.
[0062]
Also, in the above description, as shown in FIG. 10, the pitch shift circuit 22 doubles the input
low-frequency component D21 (S21) in one cycle as a unit (division), but a unit of a fixed period
Alternatively, it can be processed as if it were connected smoothly, in which case the last part of
the waveform of a certain period and the first part of the waveform of the next period will be
connected smoothly.
08-05-2019
16
[0063]
Furthermore, since low-frequency components with considerably low frequencies may be
recorded in CD, SACD, etc., in addition to the double and quadruple harmonic components when
obtaining bass feeling from these low-frequency components as well. Is an overtone component
such as 8 times, 16 times, 32 times, etc., that is, an overtone component whose frequency does
not exceed the upper limit frequency f1 and N times the low frequency component for which a
low-pitched feeling is desired (N = 2 <n>).
A harmonic component of n = 1 to 6 can be added.
[0064]
[List of Abbreviations] A / D: Analog to Digital CD: Compact Disc D / A: Digital to Analog DSP:
Digital Signal Processor SACD: Super Audio CD
[0065]
It is a systematic diagram showing one form of this invention.
It is a frequency characteristic figure for demonstrating this invention.
It is a frequency characteristic figure for demonstrating this invention.
It is a systematic diagram which shows the other form of this invention. It is a frequency
characteristic figure for demonstrating this invention. It is a systematic diagram which shows the
other form of this invention. It is a frequency characteristic figure for demonstrating this
invention. It is a wave form diagram for explaining this invention. It is a systematic diagram
showing one form of a circuit which can be used for this invention. It is a wave form diagram for
demonstrating FIG. It is a systematic diagram for explaining this invention. It is a frequency
characteristic figure for demonstrating the circuit of FIG. It is a frequency characteristic figure for
demonstrating the circuit of FIG.
08-05-2019
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Explanation of sign
[0066]
DESCRIPTION OF SYMBOLS 1 ... Input terminal, 2 ... High pass filter, 5 ... Speaker, 11, 21 and 41
... Band pass filter, 13, 23 and 43 ... Attenuator circuit, 22 and 42 ... Pitch shift circuit
08-05-2019
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