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DESCRIPTION JP2014183392

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DESCRIPTION JP2014183392
PROBLEM TO BE SOLVED: To provide a frequency characteristic correction device capable of
automatically correcting the frequency characteristic of a received signal output by a speaker
without the user's awareness. SOLUTION: The present invention has frequency characteristic
correction means and correction characteristic information formation means. The correction
characteristic information forming means is configured to output a sound from the speaker and
to receive voice that has arrived to the microphone through the echo path, and to obtain a
frequency characteristic of a transmission signal obtained by capturing the microphone and a
received signal to be output from the speaker. Based on the difference from the frequency
characteristic, correction information of the frequency characteristic to be executed by the
frequency characteristic correction means is formed. [Selected figure] Figure 1
Frequency characteristic correction device and program
[0001]
The present invention relates to a frequency characteristic correction apparatus and program,
and is applicable to, for example, a smartphone.
[0002]
Currently, IP phones using VoIP (Voice over IP) are in widespread use.
There is one that realizes this as an application such as a personal computer (PC), and it is
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1
generally called a soft phone. 2. Description of the Related Art In recent years, portable
information terminals called smartphones have become widespread, and the case where soft
phones are realized as applications on smartphones has become mainstream.
[0003]
However, smartphones, like PCs, are not devices specialized for voice communication, so the
frequency characteristics of audio signal output devices (earpieces and speakers) are different for
each model, and the models are the same. However, the variation between products is also large,
and it is necessary to correct the frequency characteristics for each product.
[0004]
In order to solve such a problem, for example, a frequency characteristic automatic correction
method as described in Patent Document 1 is applicable.
The conventional method as described in Patent Document 1 reproduces a signal having
frequency characteristics such as white noise (M-sequence signal in Patent Document 1) from a
speaker, and captures it with a measurement microphone provided at a predetermined position.
The captured signal is analyzed to obtain frequency characteristics and the like, parameters to be
set in the equalizer are determined, and the parameters are set in the frequency correction
equalizer.
[0005]
Japanese Patent Application Laid-Open No. 7-74565
[0006]
However, the prior art as described in Patent Document 1 requires a specific reference signal as
a premise to analyze the frequency, or requires an installation operation of an instrument for
measurement, etc. There were large restrictions on the environment and application conditions.
For example, it is unsuitable as a method applied when the user of a smart phone corrects the
frequency characteristic of a smart phone.
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2
[0007]
The present invention has been made in view of the above points, and an object thereof is to
provide a frequency characteristic correction apparatus and program capable of automatically
correcting the frequency characteristic of a sound signal without the user's awareness .
[0008]
According to a first aspect of the present invention, there is provided a frequency characteristic
correction apparatus for correcting the frequency characteristic of an output sound signal which
is a signal of sound output from a sound generation output device, (1) correcting the frequency
characteristic of the output sound signal; (2) Frequency characteristics of the input sound signal
obtained by the sound capturing means capturing the sound coming from the sound output
device and coming through the echo path And correction characteristic information forming
means for forming correction information of frequency characteristics to be executed by the
frequency characteristic correction means based on the difference between the frequency
characteristics of the output sound signal.
[0009]
A second aspect of the present invention is a frequency characteristic correction program for
correcting the frequency characteristic of an output sound signal which is a sound signal output
from a sound generation output device, which comprises: Frequency characteristic correction
means for correcting the frequency characteristic and outputting it to the sound output device
side, (2) Sound output from the sound output device, the sound acquisition means captures the
sound coming through the echo path It is characterized in that it functions as correction
characteristic information forming means for forming correction information of the frequency
characteristic to be executed by the frequency characteristic correction means based on the
difference between the frequency characteristic of the input sound signal and the frequency
characteristic of the output sound signal. Do.
[0010]
According to the present invention, it is possible to provide a frequency characteristic correction
apparatus and program capable of automatically correcting the frequency characteristic of a
sound signal without the user's awareness.
[0011]
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3
It is a block diagram showing functional composition of a frequency characteristic amendment
device of a 1st embodiment.
It is an explanatory view showing various frequency characteristics used for operation
explanation of a frequency characteristic amendment device of a 1st embodiment.
It is a block diagram which shows the functional structure of the frequency characteristic
correction | amendment apparatus of 2nd Embodiment.
It is a block diagram which shows the functional structure of the frequency characteristic
correction | amendment apparatus of 3rd Embodiment.
[0012]
(A) First Embodiment Hereinafter, a first embodiment of a frequency characteristic correction
apparatus and program according to the present invention will be described with reference to the
drawings.
[0013]
(A-1) Configuration of First Embodiment FIG. 1 is a block diagram showing a functional
configuration of a frequency characteristic correction device according to a first embodiment.
[0014]
The frequency characteristic correction apparatus according to the first embodiment can be
configured as hardware such as a dedicated IC chip, or can also be built as software such as a
CPU and a program executed by the CPU. Functionally, it can be represented in FIG.
As an example of software configuration, an example of an application installed in a smartphone
can be given.
[0015]
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In FIG. 1, the frequency characteristic correction device 1 according to the first embodiment
includes a frequency characteristic correction unit 2 and a correction characteristic information
formation unit 3.
[0016]
The frequency characteristic correction unit 2 corrects the frequency characteristic of the
reception signal ri (n) (where n is a parameter representing time), which is a digital signal
received from the opposite device, from the correction characteristic information formation unit
3. It is corrected according to the information F (k) to obtain a received signal (hereinafter
referred to as an output received signal) ro (n) directed to a speaker (not shown).
The frequency characteristic correction unit 2 is, for example, a digital filter.
The output reception signal ro (n) is converted into an analog signal by a digital / analog
conversion unit (not shown), and then sounded and output from a speaker (not shown).
[0017]
To the correction characteristic information forming unit 3, in addition to the reception signal ri
(n), a transmission signal s (n) obtained by converting an analog / digital conversion unit (not
shown) into a digital signal is provided.
The correction characteristic information formation unit 3 has a frequency characteristic of the
reception signal ri (n) and a transmission signal s (n) (in other words, an echo signal) obtained by
capturing the reception signal output from the speaker by the microphone. The correction
characteristic information F (k) is formed based on the frequency characteristics of The
correction characteristic information F (k) is information for matching the frequency
characteristic of the original reception signal ri (n) with the frequency characteristic of the
transmission signal s (n).
[0018]
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In general, microphones have flat frequency characteristics, but the frequency characteristics of
speakers are not flat. In addition, the speaker has different frequency characteristics for each
model, and even if the models are the same, the variation for each product is large. Therefore,
when the original reception signal ri (n) (an analog signal) is output from the speaker, the
frequency characteristics of the sound output by the output are considerably different from the
frequency characteristics of the reception signal ri (n). .
[0019]
Therefore, in the first embodiment, the frequency characteristic of the reception signal ri (n) is
corrected so that the frequency characteristic of the sound output from the speaker matches the
frequency characteristic of the original reception signal ri (n). The output reception signal ro (n)
is formed by correction according to the information F (k).
[0020]
The correction characteristic information formation unit 3 includes a reception side power
normalization unit 10, a reception side FFT (fast Fourier transform) unit 11, a transmission side
power normalization unit 12, a transmission side FFT unit 13, a correlation determination unit
14, and a comparison analysis. It has a part 15.
[0021]
In the correction characteristic information forming unit 3, the transmission signal s (n), the
reception signal ri (n) and the output reception signal ro (n) may be referred to as the number of
samples for a fixed time (hereinafter referred to as a frame). ) Is cut out and processed.
[0022]
The reception side power normalization unit 10 normalizes the reception signal ri (n) with the
signal power of the reception signal itself, and the transmission side power normalization unit 12
transmits the transmission signal s (n) The signal power is used to normalize the signal itself.
Therefore, the normalized reception signal Ri (n) output from the reception side power
normalization unit 10 and the normalized transmission signal S (n) output from the transmission
side power normalization unit 12 are: It will be full of power.
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[0023]
The receiving side FFT unit 11 converts the normalized received signal Ri (n) into frequency
information (frequency characteristics) RF (k) (k represents a frame) in frame units, and the
transmitting side FFT unit 13 is to convert the normalized transmission signal S (n) into
frequency information SF (k) in frame units.
Note that the conversion method to frequency information is not limited to FFT.
The receiving side FFT unit 11 has a function of holding frequency information RF (k) to RF (k-N)
of a predetermined number of nearest frames.
[0024]
The correlation determination unit 14 selects the receiving side that has the highest correlation
with the transmitting side frequency information SF (k) of the current frame among the held
receiving side frequency information RF (k) to RF (k−N). The frequency information RF (x) is
searched for, and the frequency information RF (x) on the receiving side searched and the
frequency information SF (k) on the transmitting side are given to the comparison and analysis
unit 15. It should be noted that even if the frequency information RF (x) on the receiving side
with the highest correlation is less than a predetermined threshold, it may be treated as not being
able to be searched. This is because, for example, during the double talk, it is not appropriate to
perform the correction of the frequency characteristic according to the first embodiment. In
consideration of such a point, instead of comparison with the threshold value, a double talk
detection unit is provided, and the correction characteristic information formation unit 3
functions effectively only in the single talk period of only the reception signal ri (n). good.
[0025]
The comparison analysis unit 15 subtracts the frequency information SF (k) on the sending side
from the frequency information RF (x) on the receiving side for each frequency component, and
obtains the obtained frequency information as the correction characteristic information F (k). It is
given to the correction unit 2.
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[0026]
(A-2) Operation of First Embodiment Next, the operation of the frequency characteristic
correction device 1 of the first embodiment will be described with reference to the drawings.
[0027]
In the softphone of the smart phone on which the frequency characteristic correction device 1 is
installed, when the call with the opposite telephone terminal is started, the frequency
characteristic correction device 1 starts operation.
[0028]
The reception signal ri (n) from the opposing device is converted into an analog signal by a
digital / analog conversion unit (not shown) after passing through the correction characteristic
information forming unit 3, and is output from a speaker (not shown).
The received voice that has been sounded and output is looped into a microphone (not shown)
via an echo path, captured by the microphone, converted into a digital signal by an analog /
digital converter, and frequency characteristic correction as a transmission signal s (n) It is input
to the device 1.
[0029]
The reception signal ri (n) is normalized by the reception side power normalization unit 10 with
the signal power of the reception signal itself, and then converted by the reception side FFT unit
11 into frequency information RF (k) in frame units, The frequency information RF (k) to RF
(k−N) of the latest predetermined number of frames is held in the receiving side FFT unit 11.
[0030]
On the other hand, the transmission signal s (n) is normalized by the transmission power of the
transmission signal itself by the transmission side power normalization unit 12, and then the
transmission side FFT unit 13 performs frequency information SF in frame units. converted to k).
[0031]
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Then, among the frequency information RF (k) to RF (k−N) on the reception side held in the
reception side FFT unit 11 by the correlation determination unit 14, the frequency information
SF on the transmission side of the current frame The receiver frequency information RF (x)
having the highest correlation with the above is searched, and the searched receiver frequency
information RF (x) and the transmitter frequency information SF (k) are given to the comparison
analysis unit 15 Be
The comparison analysis unit 15 subtracts the frequency information SF (k) on the sending side
from the frequency information RF (x) on the receiving side for each frequency component, and
the obtained frequency information is used as the correction characteristic information F (k) as
the frequency characteristic It is given to the correction unit 2.
[0032]
Thereby, the correction characteristic information F (k) is set as the frequency characteristic of
the frequency characteristic correction unit 2, and the frequency characteristic of the reception
signal ri (n) is corrected according to the correction characteristic information F (k).
[0033]
For example, the transmitting side frequency information SF (k) of the current frame obtained
from the transmitting signal s (n) has a characteristic as shown by the broken line in FIG. 2A, and
is obtained from the receiving signal ri (n). If the receiving side frequency information RF (x)
having the highest correlation with the transmitting side frequency information SF (k) has a
characteristic as shown by the solid line in FIG. 2A, the correction characteristic information F (k)
is obtained. ) (= RF (x) -SF (k)) has a characteristic as shown in FIG.
[0034]
When the frequency characteristic of the reception signal ri (n) is corrected with this correction
characteristic information F (k), the frequency component attenuated by being generated and
output from the speaker is temporarily amplified by correction when viewed after power
normalization. The frequency component amplified by being output from the speaker is
attenuated by the correction, and when the output reception signal ro (n) subjected to such
correction is generated and output, the frequency component amplified by the correction is the
speaker The frequency component attenuated by the sound output by the speaker and the
frequency component attenuated by the correction is amplified by the sound output by the
speaker, and the frequency characteristic of the sound generated and output from the speaker is
similar to the frequency characteristic of the original reception signal ri (n) It becomes.
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[0035]
That is, by the above correction, the frequency characteristic of the sound produced and output
from the speaker is the frequency characteristic of the original reception signal ri (n) regardless
of the dispersion of the frequency characteristic of each speaker model and the dispersion of
each product. Would be similar to
[0036]
The operation in the frequency characteristic correction device 1 may be ended when a
predetermined period (for example, 10 seconds) which has been determined in advance has
elapsed from the call start time.
Further, the operation in the frequency characteristic correction device 1 may be performed
during a call.
Furthermore, the operation in the frequency characteristic correction device 1 may be ended
when the levels of all frequency components in the correction characteristic information F (k) fall
within a predetermined narrow range.
[0037]
In the above description, although what automatically makes the operation in the frequency
characteristic correction device 1 effective upon the start of a call is shown, it is possible for the
user to select whether or not the operation in the frequency characteristic correction device 1 is
effective. Alternatively, the operation of the frequency characteristic correction device 1 may be
enabled during a call in a state where it is selected to be enabled (selection by dip switch,
selection from application, etc.).
[0038]
(A-3) Effects of the First Embodiment According to the first embodiment, the user automatically
compensates for the influence of the frequency characteristic of the speaker without being aware
of the correction of the frequency characteristic during a call. The frequency characteristic of the
incoming call signal can be corrected and sound can be output.
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[0039]
Moreover, according to the first embodiment, no special reference signal is necessary because of
the frequency characteristics of the reception signal, and the reception signal itself can be used
as a reference signal, and generation of a special reference signal such as a white noise signal
The circuit can be eliminated.
[0040]
Note that providing a reference signal generation circuit and generating a reference signal to
obtain correction characteristic information F (k) constitutes a modified embodiment of the first
embodiment.
For example, a frequency characteristic correction function may be provided as one of setting
functions immediately after purchasing a smartphone, etc. In such a case, a white noise signal or
the like can be used to correct the frequency characteristic.
[0041]
(B) Second Embodiment Next, a second embodiment of the frequency characteristic correction
apparatus and program according to the present invention will be described with reference to the
drawings.
[0042]
FIG. 3 is a block diagram showing the functional configuration of the frequency characteristic
correction apparatus of the second embodiment, and the same or corresponding parts are given
the same or corresponding parts as in FIG. 1 according to the first embodiment. It shows.
[0043]
The frequency characteristic correction device 1A of the second embodiment is installed in a
smartphone.
The frequency characteristic correction apparatus 1A of the second embodiment has a second
frequency characteristic correction unit 16 and a user attribute determination unit 17 in addition
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to the same configuration as the frequency characteristic correction apparatus 1 of the first
embodiment.
[0044]
The user attribute determination unit 17 takes in user information from an application that
manages user information of a smartphone in which the frequency characteristic correction
device 1A is installed, obtains an attribute of the user (user), and The second correction
characteristic information F2 to be set in the frequency characteristic correction unit 16 is
obtained.
[0045]
The second frequency characteristic correction unit 16 is, for example, a digital filter, and
corrects the frequency characteristic of the reception signal ri (n) from the opposite device
according to the second correction characteristic information F2, and corrects the reception
signal ri2 (n ) To the frequency characteristic correction unit 2 and the correction characteristic
information formation unit 3.
[0046]
For example, the user attribute determination unit 17 includes a table in which the second
correction characteristic information F2 is associated with the age of the user, determines
whether the user's age is several tens from the user information, and the age The second
correction characteristic information F2 suitable for the above is read out from the table and
given to the second frequency characteristic correction unit 16.
As a result, the post-correction reception signal ri2 (n) output from the second frequency
characteristic correction unit 16 has frequency characteristics that can be easily heard by people
of that age.
For example, if the user is in his 60s, the high frequency component is lifted.
[0047]
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The attribute of the user is not limited to the age.
For example, it may be a combination of age and gender.
[0048]
According to the second embodiment, the correction of the frequency characteristic in
consideration of the frequency characteristic of the speaker and the correction of the frequency
characteristic in consideration of the attribute of the user can coexist without adversely affecting
each other.
[0049]
(C) Third Embodiment Next, a third embodiment of the frequency characteristic correction
apparatus and program according to the present invention will be described with reference to the
drawings.
[0050]
FIG. 4 is a block diagram showing the functional configuration of the frequency characteristic
correction apparatus of the third embodiment, and the same or corresponding parts are given the
same or corresponding parts as in FIG. 1 according to the first embodiment. It shows.
[0051]
The frequency characteristic correction device 1B of the third embodiment has a noise canceller
unit 18 in addition to the same configuration as the frequency characteristic correction device 1
of the first embodiment.
[0052]
The noise canceller unit 18 receives a transmission signal s (n) obtained by converting an analog
/ digital conversion unit (not shown) into a digital signal by a signal (not shown) acquired by a
microphone (not shown).
The noise canceller unit 18 removes the noise component contained in the transmission signal s
(n) and supplies the transmission characteristic signal forming unit 3 with the transmission
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signal s2 (n) after the removal.
[0053]
The correction characteristic information forming unit 3 basically uses the fact that the
transmission signal in which the reception signal has passed through the echo path has a very
high correlation with the reception signal, and the frequencies of the reception signal and the
transmission signal Based on the idea that the difference in characteristics is based on the
frequency characteristics of the speaker, the correction characteristic information F (k) is formed.
[0054]
However, when the smartphone equipped with the frequency characteristic correction device is
under background noise, the frequency characteristic of the background noise is also included in
the transmission signal s (n).
When the correction characteristic information F (k) is formed without removing the background
noise component, the sound to be output is the one in which the frequency characteristic of the
speaker and the frequency characteristic of the background noise are corrected, and the
reception signal It is far from ri (n).
On the other hand, as in this embodiment, when the correction characteristic information F (k) is
formed based on the transmission signal s2 (n) after the noise canceller unit 18 removes the
noise component, the first embodiment As described above, the sound to be produced and output
is very close to the reception signal ri (n) in which the frequency characteristic of the speaker is
canceled.
[0055]
Note that whether or not to enable the function of the noise canceller unit 18 may be left to the
user's selection.
[0056]
According to the third embodiment, the effects described in the first embodiment can be
exhibited even in an environment where the background noise is large.
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14
[0057]
(D) Other Embodiments In the description of each of the above embodiments, various modified
embodiments are referred to, but further, modified embodiments as exemplified below can be
mentioned.
[0058]
In each of the above embodiments, the microphone for speech is applied as the microphone for
obtaining the transmission signal s (n) for correction of the frequency characteristic, but the
microphone for correction of frequency characteristic is the microphone for the speech and It
may be provided separately.
[0059]
In each of the above embodiments, the frequency information after conversion by the FFT unit
for searching for the synchronization (correlation) between the transmission signal and the
reception signal has been described. The synchronization (correlation) with the reception signal
may be determined.
In this case, frame extraction and FFT conversion may be performed after that, and further,
normalization based on signal power may be performed after obtaining correlation.
[0060]
Although the case where one microphone is provided is shown in each of the above
embodiments, the present invention can be applied to the case where there are a plurality of
microphones.
For example, correction characteristic information may be obtained for each capture signal of
each microphone, and average correction characteristic information obtained by averaging a
plurality of correction characteristic information for each frequency component may be given to
the frequency characteristic correction unit 2.
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[0061]
In each of the above embodiments, the frequency characteristic correction apparatus of the
present invention is mounted on a smartphone. However, the frequency characteristic correction
apparatus of the present invention can be applied to other voice communication apparatuses
such as a television conference apparatus.
Furthermore, the frequency characteristic correction device of the present invention can be
applied to a device that handles musical tone signals such as a music player and a karaoke
device, an acoustic signal, and the like.
What is expressed as "sound signal" in the claims means "sound signal", "musical tone signal",
"acoustic signal", etc. which are output by the sound output device.
[0062]
1, 1A, 1B: frequency characteristic correction device, 2: frequency characteristic correction unit,
3: correction characteristic information formation unit, 10: reception side power normalization
unit, 11: reception side FFT unit, 12: transmission side power normalization 13: transmission side
FFT unit 14: correlation determination unit 15: comparison analysis unit 16: second frequency
characteristic correction unit 17: user attribute determination unit 18: noise canceler unit
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