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JP2010154563

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DESCRIPTION JP2010154563
A correction is performed to reduce resonance characteristics. An acoustic characteristic
correction device suppresses a primary resonance peak in a frequency band including a primary
resonance frequency taking a primary resonance peak of the frequency characteristic from a
frequency characteristic representing an acoustic characteristic of a user's ear canal. An acoustic
model adaptive filter 311 having an acoustic model adaptive filter 311 having a characteristic of
suppressing a secondary resonance peak in a frequency band including a secondary resonance
frequency taking a secondary resonance peak of the frequency characteristic at a non-integer
multiple of the primary resonance frequency; And a sound source output mode processing unit
302 that performs filter processing using an acoustic model adaptive filter 311 on the signal.
[Selected figure] Figure 15
Sound reproduction device
[0001]
The present invention relates to a sound reproduction apparatus.
[0002]
2. Description of the Related Art Conventionally, a sound reproduction device excellent in
portability that can hear reproduction sound such as music using headphones has been widely
spread.
08-05-2019
1
In such a sound reproducing apparatus, the user often listens to music etc. at his / her favorite
volume. As a result, there is a situation where a relatively loud sound is heard for a long time.
Under such circumstances, there is a risk of reducing the hearing ability of the user listening to
music or the like. Therefore, various techniques have been proposed to prevent this.
[0003]
For example, in the technique described in Patent Document 1, a technique of dividing the
frequency band to facilitate correction is described.
[0004]
WO1995/020866パンフレット
[0005]
However, the prior art of the above-mentioned Patent Document 1 is merely a technique for
correcting for reflection noise, and is not a technique for considering even resonance
characteristics.
[0006]
The present invention has been made in view of the above, and provides an acoustic
reproduction apparatus capable of performing processing based on resonance characteristics of
an object to be measured.
[0007]
In order to solve the problems described above and to achieve the object, the sound reproducing
apparatus according to the present invention has a first resonance that takes a first resonance
peak of the frequency characteristic from a frequency characteristic representing the acoustic
characteristic of the object to be measured. The characteristic in which the first resonance peak
is suppressed in a frequency band including a frequency, and the high-order resonance
frequency in a frequency band including a second resonance peak of the frequency characteristic
at a non-integer multiple of the first resonance frequency It is characterized by comprising: filter
means having a second resonance peak suppressing characteristic; and processing means for
performing filter processing on the acoustic signal using the filter means.
[0008]
According to the present invention, by combining the acoustic models generated for each
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2
frequency band, it is possible to perform correction processing suitable for the acoustic
characteristics of the object to be measured even if the interval between the resonance peaks is
not an integral multiple. Play.
[0009]
FIG. 1 is a diagram showing an example of the sound reproduction device according to the first
embodiment.
FIG. 2 is a conceptual diagram showing an earphone used for correction of resonance
characteristics and the surrounding environment in the first embodiment.
FIG. 3 is a block diagram showing the configuration of the acoustic characteristic correction
device according to the first embodiment.
FIG. 4 is a conceptual diagram showing the ear canal when the earphone is not attached.
FIG. 5 is a diagram showing frequency characteristics of the ear canal when the earphone is not
attached.
FIG. 6 is a conceptual view showing the ear canal when wearing the earphone.
FIG. 7 is a diagram showing frequency characteristics of the ear canal when the earphone is
worn. FIG. 8 is a view showing a concept in which the ear canal on which the earphone is
mounted is assumed to be a uniform resonance tube blocked by the earphone and a wall
(tympanic membrane). FIG. 9 is a conceptual diagram showing fundamental vibration in a
uniform resonance tube. FIG. 10 is a conceptual diagram showing double oscillation in a uniform
resonance tube. FIG. 11 is a diagram showing frequency characteristics of a uniform resonance
tube representing the ear canal. FIG. 12 is a conceptual diagram showing the inverse
characteristic of the resonance generated in the uniform resonance tube. FIG. 13 is a diagram
showing the configuration of a comb filter showing the inverse characteristic of resonance. FIG.
14 is a diagram showing the frequency characteristics of the ear canal having acoustic
characteristics that are not flat on the frequency axis and the inverse characteristics of the
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uniform resonance tube. FIG. 15 is a block diagram showing each configuration for constructing
an acoustic model in the acoustic model adaptive filter. FIG. 16 is a diagram showing the concept
of an acoustic model constructed in an acoustic model adaptive filter. FIG. 17 is a flowchart
showing an overall processing procedure of the acoustic characteristic correction device. FIG. 18
is a flowchart showing the processing procedure in the correction setting mode in the acoustic
characteristic correction device according to the first embodiment. FIG. 19 is a flowchart showing
a processing procedure until an acoustic signal is output in the acoustic characteristic correction
device according to the first embodiment. FIG. 20 is a diagram showing the concept of an
acoustic model constructed in an acoustic model adaptive filter according to a modification. FIG.
21 is a diagram showing a hardware configuration of the acoustic characteristic correction
device.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, with reference to the
accompanying drawings, the best mode for carrying out the sound reproduction apparatus
according to the present invention will be described in detail.
[0011]
First Embodiment FIG. 1 is a diagram showing an example of a sound reproduction device 100 to
which the sound characteristic correction device of the first embodiment is applied.
In the example shown in FIG. 1, the sound reproduction device 100 is configured of a sound
characteristic correction device 150 and a mobile phone terminal 110. Then, the acoustic
characteristic correction device 150 includes the earphone 120 and the housing unit 130.
[0012]
In the mobile phone terminal 110, an internal (not shown) audio data generation unit generates
(reproduces) audio data and outputs the audio data to the acoustic characteristic correction
device 150. The acoustic characteristic correction device 150 corrects the resonance
characteristic of the input voice data (sound source signal), and then outputs the corrected
acoustic signal from the earphone 120 to the non-target measurement object. In the present
embodiment, the non-target measurement object is an example of the user's ear canal. Also, the
earphone 120 has a built-in microphone. Next, the earphone 120 will be described.
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4
[0013]
FIG. 2 is a conceptual view showing the earphone 120 used for the correction of the resonance
characteristic and the surrounding environment in the present embodiment. As shown in FIG. 2,
an earphone 120 is attached to the entrance of the ear canal. In the vicinity of the sound output
unit 201 (sound tube unit) of the earphone 120, the sound input unit 202 of the microphone is
disposed. The acoustic output unit 201 of the earphone 120 and the acoustic input unit 202 of
the microphone are electrically connected to the housing 130 of the acoustic characteristic
correction device 150, respectively. The acoustic signal output from the acoustic output unit 201
is delivered to the eardrum position 250 of the ear canal.
[0014]
In addition, in FIG. 2, the sound input part 202 of a microphone was expressed as another
structure with the sound output part 201 of the earphone 120 so that it was easy to visually
recognize. In fact, it is assumed that it is provided inside the earphone 120 and in the vicinity of
the sound output unit 201.
[0015]
FIG. 3 is a block diagram showing the configuration of the acoustic characteristic correction
device 150 according to the first embodiment. As shown to this figure, the acoustic characteristic
correction apparatus 150 is comprised by the housing | casing part 130 and the earphone 120.
As shown in FIG.
[0016]
The earphone 120 includes an electric / acoustic converter 303, an acoustic output unit 201, and
a microphone 330. The microphone 330 includes an acoustic input unit 202 and an acoustic /
electric conversion unit 306.
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[0017]
The electrical / acoustic conversion unit 303 converts a sound source signal, which is an
electrical signal input from the housing unit 130, into an acoustic signal. The sound output unit
201 outputs a sound signal.
[0018]
The acoustic input unit 202 of the microphone 330 inputs and processes an acoustic signal from
inside the human ear canal. In the present embodiment, when a sound signal for measurement
(hereinafter referred to as a measurement sound signal) is output from the sound output unit
201, a response sound signal corresponding to the measurement sound signal is input-processed.
As described above, the sound input unit 202 is provided in the vicinity of the sound output unit
201.
[0019]
The acoustic / electrical conversion unit 306 converts the input processed acoustic signal
(response acoustic signal) into an electrical signal. In this embodiment, the response acoustic
signal converted into the electrical signal is used as the response signal.
[0020]
By the way, if it is possible to cancel the resonance frequency of the tympanic membrane
position, it means that the user has made appropriate correction, but it is difficult to arrange the
microphone at the tympanic position of the user every time it is used. Therefore, in the present
embodiment, the microphone is disposed in the vicinity of the earphone 120.
[0021]
In the present embodiment, the resonance characteristic of the ear canal is measured while the
earphone 120 is thus worn. FIG. 4 is a conceptual view showing the ear canal when the earphone
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is not attached. As shown in FIG. 4, the ear canal can be represented as a one-sided closed tube
when the earphone is not worn. FIG. 5 is a diagram showing frequency characteristics of the ear
canal when the earphone is not attached. As shown in FIG. 5, there are a plurality of resonance
peaks as frequency characteristics of the ear canal.
[0022]
FIG. 6 is a conceptual view showing the ear canal when wearing the earphone. As shown in FIG.
6, at the stage of wearing the earphone, the ear canal can be represented as a both-side closed
tube. FIG. 7 is a diagram showing frequency characteristics of the ear canal when the earphone is
worn. As shown in FIG. 7, there are a plurality of resonance peaks as frequency characteristics of
the ear canal.
[0023]
Then, comparing the frequency characteristics of the ear canal shown in FIG. 5 with the
frequency characteristics of the ear canal shown in FIG. 7, the resonance frequency taken as the
resonance peak and the gain of the resonance frequency are between the non-wearing and
wearing of the earphone. It can confirm that it is different. Thus, the ear canal changes from a
one-sided closed tube to a two-sided closed tube by the attachment of the user's earphone, and a
change in the spectral structure can be seen.
[0024]
In such changes in spectral structure, particularly changes in the resonance frequency may
adversely affect hearing. Therefore, in the present embodiment, in the case where the object to
be measured is the ear canal, the resonance frequency changed due to the arrival of the
earphone is corrected.
[0025]
FIG. 8 shows a concept in which the ear canal on which the earphone is mounted is assumed to
be a uniform resonance tube blocked by the earphone and a wall (tympanic membrane). In this
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case, innumerable resonance frequencies occur such as the resonance frequency (first resonance
peak) of the fundamental vibration as shown in FIG. 9 and the resonance frequency (second
resonance peak) of the double vibration as shown in FIG.
[0026]
FIG. 11 is a diagram showing frequency characteristics of a uniform resonance tube representing
the ear canal. As shown in FIG. 11, the acoustically harmful resonance frequency exists at an
integral multiple of the fundamental vibration. It is necessary to make corrections to remove
these resonance frequencies. In the case of such frequency characteristics, the resonance can be
suppressed by using the inverse characteristic of the uniform resonance tube as shown in FIG.
[0027]
The filter having the frequency characteristic shown in FIG. 12 is generally called a comb filter.
FIG. 13 is a diagram showing the configuration of the comb filter. As shown in FIG. 13, the comb
filter can be realized by a combination of n delay elements (z1 to zn) and amplification elements
(b1 to bn).
[0028]
However, the ear canal has a complicated shape including a constriction portion, and the
resonance frequency may not appear in integral multiples as in a uniform acoustic tube. As
described above, when the ear canal has acoustic characteristics that are not flat on the
frequency axis, a model that assumes a uniform acoustic tube can not cope with it, and even if
the inverse characteristic of the uniform resonance tube described above is used, the resonance
can not be achieved. It is difficult to deter properly.
[0029]
FIG. 14 is a diagram showing the frequency characteristics of the ear canal having acoustic
characteristics that are not flat on the frequency axis and the inverse characteristics of the
uniform resonance tube. In the example shown in FIG. 14, when the frequency of the
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fundamental vibration is n, the frequency of the double vibration is not 2n, and the frequency of
the triple vibration is not 3n. That is, when the inverse characteristic of the uniform resonance
tube shown in FIG. 14 is used, the resonance of the first resonance peak can be suppressed, but
the resonance of the second and subsequent resonance peaks can not be suppressed.
[0030]
That is, in the method described above, when the ear canal has acoustic characteristics that are
not flat on the frequency axis, it is not possible to suppress the resonance of all the resonance
peaks. In order to suppress the resonance, identification of the frequency of the resonance
characteristic of the ear canal may be performed, but the calculation process becomes heavy and
the cost becomes high. Furthermore, because there is a possibility of picking up factors other
than the characteristics of the ear, it is not always possible to identify the exact frequency of the
ear canal.
[0031]
Therefore, in the present embodiment, in order to solve the above-described problems, different
acoustic models are constructed for each frequency band. First, referring back to FIG. 3, each
configuration will be described.
[0032]
The housing unit 130 includes a sound source input unit 301, a sound source output mode
processing unit 302, a correction setting mode processing unit 307, and a switching unit 308.
[0033]
The acoustic characteristic correction device 150 according to the present embodiment includes
two types of processing modes.
One of these processing modes is a correction setting mode, in which the frequency
characteristic of the user's ear canal is measured, and the acoustic model parameter used in the
acoustic model adaptive filter 311 is specified. The other mode is set as a sound source output
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mode, and after correction processing of a sound source signal is performed by an acoustic
model adaptive filter 311 using an acoustic model to which the above parameters are applied, a
mode is output as an acoustic signal.
[0034]
The acoustic model is assumed to model the frequency characteristics of the user's ear canal. The
acoustic model according to the present embodiment is generated on the basis of, in particular, a
resonance peak among frequency characteristics of the user's ear canal.
[0035]
The switching unit 308 switches between the correction setting mode and the sound source
output mode. Then, in the case of the correction setting mode, processing for constructing an
acoustic model used by the correction filter by the correction setting mode processing unit 307
is performed. On the other hand, in the case of the sound source output mode, after the sound
source output mode processing unit 302 processes the sound source signal input to the sound
source input unit 301, an acoustic signal is output to the object to be measured. .
[0036]
In the present embodiment, an electrical signal input from the mobile phone terminal 110 as
voice data is used as a sound source signal. The sound signal is the sound output from the sound
output unit 201 of the earphone 120.
[0037]
The correction setting mode processing unit 307 includes a measurement signal generation unit
321, a parameter specification unit 322, a characteristic specification unit 323, and a response
data acquisition unit 324. In the present embodiment, when the switching unit 308 switches to
the sound source output mode, processing of each configuration is performed using generation
of the measurement reference signal of the measurement signal generation unit 321 as a trigger.
08-05-2019
10
[0038]
The measurement signal generation unit 321 generates a measurement reference signal
indicating an electrical signal for measuring the resonance characteristic (frequency
characteristic) of the ear canal. The measurement reference signal is an electrical signal
predetermined to measure the resonance characteristic of the ear canal.
[0039]
Then, the measurement reference signal generated by the measurement signal generation unit
321 is converted into an acoustic signal by the electric / acoustic conversion unit 303. The
measurement reference signal converted into the acoustic signal is taken as a measurement
acoustic signal. The measurement acoustic signal according to this embodiment includes a
plurality of sine waves including at least one of unit pulses, time-stretched pulses, white noise,
band noise including a measurement band, and sine waves in the measurement band. Let it be a
signal synthesized by waves.
[0040]
Then, the measurement acoustic signal converted by the electric / sound conversion unit 303 is
output from the sound output unit 201. Thereafter, the acoustic input unit 202 performs an
input process on the response acoustic signal (which is a reflected sound) corresponding to the
output measurement acoustic signal. Then, the response acoustic signal subjected to the input
processing is converted into an electrical signal by the acoustic / electrical conversion unit 306.
The converted electrical signal is used as a response signal.
[0041]
The response data acquisition unit 324 acquires a response signal. The response signal is a signal
obtained by converting the response acoustic signal reflected by the ear canal into an electrical
signal.
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11
[0042]
The characteristic specifying unit 323 analyzes the frequency characteristic of the acquired
response signal to specify the resonance characteristic of the ear canal. The characteristic
specifying unit 323 according to the present embodiment specifies the resonance frequency for
each resonance peak by analyzing the response signal. As a method of specifying the resonance
frequency, any method may be used regardless of a known method.
[0043]
Characteristic specifying unit 323 according to the present embodiment specifies resonance
characteristics for each frequency band. For example, the property specifying unit 323 specifies
the resonance property of the frequency band including the first resonance peak, and specifies
the resonance property of the frequency band including the second resonance peak. The
characteristic specifying unit 323 according to the present embodiment specifies the gain of each
resonance peak, the resonance frequency, and the like as the resonance characteristic.
[0044]
The parameter specifying unit 322 specifies a parameter to be set in the acoustic model for each
frequency band based on the resonance characteristic (frequency characteristic) for each
frequency band specified by the characteristic specifying unit 323. The parameter specifying unit
322 according to the present embodiment specifies a parameter set in an acoustic model based
on the first resonance peak and a parameter set in an acoustic model based on the second
resonance peak. Hereinafter, an acoustic model constructed on the basis of each resonance peak
is referred to as a partial acoustic model.
[0045]
The parameter specifying unit 322 according to the present embodiment specifies the
propagation time for each acoustic model as a parameter for setting the acoustic model for each
frequency band. Specifically, the parameter specifying unit 322 specifies the propagation time to
be set in the first partial acoustic model based on the first resonance peak, from the resonance
characteristics of the frequency band including the first resonance peak. Furthermore, the
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parameter specifying unit 322 specifies the propagation time to be set to the second acoustic
model based on the second resonance peak from the resonance characteristics of the frequency
band including the second resonance peak. The propagation time is specified using a known
method.
[0046]
Furthermore, the parameter specifying unit 322 specifies the reflectance for each acoustic model
from the detected resonance frequency and the size of each resonance peak. Specifically, the
parameter specifying unit 322 specifies the reflectance to be set in the first partial acoustic
model from the size of the first resonance peak. Furthermore, the parameter specifying unit 322
specifies the reflectance to be set to the second partial acoustic model from the size of the second
resonance peak. In addition, the said reflectance can also be specified using a well-known
method.
[0047]
As described above, the parameter specifying unit 322 sets parameters for each partial acoustic
model from the resonance characteristics specified by the property specifying unit 323. Thereby,
it is possible to perform correction processing appropriate for the frequency band. As a result,
for example, even when the resonance frequency of the fundamental vibration is not n times the
resonance frequency of the n-th vibration, appropriate correction can be performed.
[0048]
The sound source input unit 301 inputs and processes a sound source signal as a source of an
acoustic signal supplied to the ear canal.
[0049]
The sound source output mode processing unit 302 includes an acoustic model adaptive filter
311.
When switched to the sound source output mode, the sound source signal input by the sound
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source input unit 301 is subjected to processing by the acoustic model adaptive filter 311, the
electric / sound conversion unit 303, and the sound output unit 201 described below.
[0050]
The acoustic model adaptive filter 311 performs a filtering process on the sound source signal
subjected to the input processing by combining a plurality of partial acoustic models in which
parameters are set. Thereby, correction processing can be performed. FIG. 15 is a diagram
showing an example in which an acoustic model is adapted in the acoustic model adaptive filter
311. As shown in FIG.
[0051]
As shown in FIG. 15, the acoustic model adaptive filter 311 includes a first partial acoustic model
adaptation unit 1401, a first frequency band division filter 1402, a second partial acoustic model
adaptation unit 1403, and a second frequency. A band division filter 1404 and a combination
unit 1406 are provided.
[0052]
The first partial acoustic model adaptation unit 1401 generates, based on the setting of the
parameter by the parameter specification unit 322, a first partial acoustic model that is the
inverse characteristic of the resonance peak, based on the first resonance peak.
The second partial acoustic model adaptation unit 1403 generates, based on the setting of the
parameter by the parameter specification unit 322, a second partial acoustic model that is the
inverse characteristic of the resonance peak, based on the second resonance peak.
[0053]
The first frequency band division filter 1402 extracts the frequency component of the frequency
band including the first resonance peak from the first partial acoustic model generated by the
first partial acoustic model adaptation unit 1401. In this embodiment, a low pass filter for
extracting a low frequency band is used.
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[0054]
The second frequency band division filter 1404 extracts frequency components of the frequency
band including the second and subsequent resonance peaks from the second partial acoustic
model generated by the second partial acoustic model adaptation unit 1403. In this embodiment,
a high pass filter for extracting a high frequency band is used.
[0055]
The frequency dividing the frequency band including the first resonance peak and the frequency
band including the second and subsequent resonance peaks is the first resonance frequency as
the fundamental vibration and the second resonance frequency as the double vibration. An
appropriate frequency may be set from the frequency between and.
[0056]
The combination unit 1406 combines the frequency components of the frequency band including
the first resonance peak from the first partial acoustic model adaptation unit 1401 and the
second and subsequent resonance peaks from the second partial acoustic model adaptation unit
1403. And the frequency component of the included frequency band.
In other words, the combination unit 1406 includes the frequency component of the frequency
band including the first resonance peak in the first partial acoustic model, and the frequency
component of the frequency band including the second resonance peak in the second partial
acoustic model. , Is combined to mean that an acoustic model is generated.
[0057]
FIG. 16 is a diagram showing the concept of the acoustic model constructed in the acoustic
model adaptive filter 311. As shown in FIG. The first partial acoustic model 1601 shown in FIG.
16 is the first partial acoustic model generated by the first partial acoustic model adaptation unit
1401, and the second partial acoustic model 1602 is the second partial acoustic model. It is a
second partial acoustic model generated by the model adaptation unit 1403.
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[0058]
Then, in the first partial acoustic model 1601, only the frequency component of the low
frequency band including the first resonance peak is extracted by the first frequency band
division filter 1603. On the other hand, in the second partial acoustic model 1602, only
frequency components in the high frequency band including the second resonance peak are
extracted by the second frequency band division filter 1604. Then, the acoustic model 1605 used
in the acoustic model adaptive filter 311 is generated by combining the partial acoustic models
of the extracted frequency components by the combination unit 1406. Then, in the acoustic
model adaptive filter 311, the sound source signal is filtered using the generated acoustic model
1605.
[0059]
Specifically, the first partial acoustic model adaptation unit 1401 generates a first comb filter
based on the generated first partial acoustic model. A value based on the specified propagation
time and reflectance is set to the delay element (z1 to zn) and the amplification element (b1 to
bn) of the comb filter. On the other hand, the second partial acoustic model adaptation unit 1403
generates a second comb filter based on the generated second partial acoustic model.
[0060]
The sound source signal input to the first partial acoustic model adaptation unit 1401 is
corrected by the first comb filter, and then input to the first frequency band dividing filter 1402
and includes the first resonance peak. Only the source signal of the frequency band is extracted.
[0061]
On the other hand, the sound source signal input to the second partial acoustic model adaptation
unit 1403 is filtered by the second comb filter, and then input to the second frequency band
division filter 1404, and the second and subsequent resonance peaks are Only the source signal
of the included frequency band is extracted.
[0062]
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Thereafter, in the combining unit 1406, the sound source signal of the frequency band including
the first resonance peak and the sound source signal of the frequency band including the second
and subsequent resonance peaks are combined.
Thus, it is possible to generate a sound source signal that has been corrected so as to suppress
the resonance of each resonance peak.
[0063]
Next, an overall processing procedure of the acoustic characteristic correction device 150
according to the present embodiment will be described.
FIG. 17 is a flowchart showing the above-described processing procedure of the acoustic
characteristic correction device 150.
[0064]
First, the switching unit 308 determines whether to measure the frequency characteristic (step
S1701). If it is determined that the acoustic characteristic is to be measured (step S1701: YES),
the correction setting mode processing unit 307 performs processing in the correction setting
mode (step S1702).
[0065]
On the other hand, when it is determined that the frequency characteristic is not measured (step
S1701: No), or after the process of step S1702 ends, the sound source output mode processing
unit 302 performs the process in the sound source output mode (step S1703). Processing
according to each mode is performed according to the above-described processing procedure.
[0066]
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Next, processing in the correction setting mode in the acoustic characteristic correction device
150 according to the present embodiment will be described. FIG. 18 is a flowchart showing the
procedure of the above-described process in the acoustic characteristic correction device 150
according to the present embodiment.
[0067]
First, the measurement signal generation unit 321 generates a measurement reference signal
indicating an electrical signal for measuring the resonance characteristic (frequency
characteristic) of the ear canal (step S1801). Next, the electrical / acoustic conversion unit 303
converts the measurement reference signal into a measurement acoustic signal (step S1802).
Thereafter, the sound output unit 201 outputs the measurement sound signal to the ear canal
(step S1803).
[0068]
Thereafter, the sound input unit 202 performs input processing on the response sound signal
reflected from the ear canal (step S1804). Next, the acoustic / electrical conversion unit 306
converts the response acoustic signal into a response signal that is an electrical signal (step
S1805).
[0069]
Then, the response data acquisition unit 324 acquires a response signal. Next, the characteristic
specifying unit 323 specifies, from the response signal, resonance characteristics including the
resonance frequency of each resonance peak (first resonance peak, second resonance peak, etc.)
(step S1806). After that, the parameter specifying unit 322 specifies the parameter of the partial
acoustic model of each acoustic model from the specified resonance characteristics (step S1807).
Thereafter, the parameter specifying unit 322 sets the specified parameters in each partial
acoustic model, whereby a plurality of partial acoustic models are generated in the acoustic
model adaptive filter 311 (step S1808). In the present embodiment, an acoustic model having an
inverse characteristic of each resonance peak is generated.
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[0070]
According to the above-described processing procedure, a partial acoustic model for making an
appropriate correction to the user's ear canal was generated. Further, since the acoustic model
adaptive filter 311 is provided with a configuration for combining frequency components of each
partial acoustic model according to frequency bands, it means that an acoustic model combining
the respective frequency components of the partial acoustic model is constructed. Do.
[0071]
Next, the processing up to the output of an acoustic signal in the acoustic characteristic
correction device 150 according to the present embodiment will be described. FIG. 19 is a
flowchart showing the procedure of the above-described process in the acoustic characteristic
correction device 150 according to the present embodiment.
[0072]
First, the sound source input unit 301 inputs a sound source signal, which is an electric signal,
from the mobile phone terminal 110 (step S1901).
[0073]
Next, the first partial acoustic model adaptation unit 1401 and the second partial acoustic model
adaptation unit 1403 perform correction processing on the input sound source signal with the
filter using the generated partial acoustic model. The operation is performed (step S1902).
After that, the first frequency band division filter 1402 and the second frequency band division
filter 1404 extract frequency components of each frequency band with respect to the sound
source signal after the correction processing by the filter using each acoustic model. Step S1903.
After that, the combination unit 1406 combines the sound source signals of the frequency
components of the extracted frequency bands (step S1904). As a result, the sound source signal
in which the appropriate correction is performed for each frequency band is generated.
[0074]
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Thereafter, the electrical / acoustic conversion unit 303 converts the combined sound source
signal into an acoustic signal (step S1905). Thereafter, the sound output unit 201 outputs the
sound signal to the ear canal (step S1906).
[0075]
According to the above-described processing procedure, even if the external ear canal has a
complicated shape including a narrowed portion and the resonance frequency does not appear at
integral multiples like a uniform sound tube, an acoustic signal subjected to correction
processing according to the external ear canal Can be output.
[0076]
In the present embodiment, an example in which the earphone 120 is applied has been
described, but the present invention is not limited to the earphone, and may be, for example,
headphones.
[0077]
The acoustic characteristic correction device 150 according to the present embodiment makes it
possible to perform correction in accordance with the characteristics of an individual's ear.
In addition, the acoustic characteristic correction device 150 can also perform correction in
accordance with the difference between the left and right ears and the insertion state.
[0078]
Furthermore, since the acoustic characteristic correction device 150 according to the present
embodiment performs the correction for suppressing the resonance peak, it is possible to
perform the correction with less deterioration of the sound quality.
In addition, since resonance characteristics are used and identification results of resonance
characteristics are not used, tuning can be easily performed with a small number of parameters.
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In addition, arithmetic processing can be reduced.
[0079]
The acoustic characteristic correction device 150 according to the present embodiment combines
partial acoustic models generated with reference to each resonance peak. As a result, the
processing load can be reduced and the cost of the device can be reduced, as compared to the
case of identifying the resonance characteristic of the user.
[0080]
The acoustic characteristic correction device 150 according to the present embodiment can
perform simple and flexible correction on the resonance characteristic of the object to be
measured having acoustic characteristics that are not flat on the frequency axis. It can be
improved. Further, as compared with the case where resonance characteristics are identified, no
factor other than the ear enters, so that the accuracy of correction can be improved and the
sound quality characteristics can be improved.
[0081]
Modified Example In the first embodiment, the case where the filter to which the acoustic model
for removing the resonance peak is applied is generated is described. However, the present
invention is not limited to the generation of such an acoustic model, and an acoustic model
representing each resonance peak may be generated. Thus, as a modification, an example of
constructing an acoustic model representing each resonance peak will be described. In addition,
about another structure, description is abbreviate | omitted as it is the same as that of 1st
Embodiment.
[0082]
FIG. 20 is a diagram showing the concept of the acoustic model constructed in the acoustic
model adaptive filter 311 according to the present modification. The first partial acoustic model
2001 shown in FIG. 20 is an acoustic model generated by the first partial acoustic model
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adaptation unit 1401, and the second partial acoustic model 2002 is a second partial acoustic
model adaptation unit 1403. Is a generated acoustic model.
[0083]
Then, in the first partial acoustic model 2001, only the frequency component of the low
frequency band including the first resonance peak is extracted by the first frequency band
division filter 2003. On the other hand, in the second partial acoustic model 2002, only the
frequency component of the high frequency band including the second resonance peak is
extracted by the second frequency band division filter 2004. Then, the acoustic model 2005 used
in the acoustic model adaptive filter 311 is generated by combining the partial acoustic models
of the extracted frequency components by the combination unit 1406. Then, the acoustic model
adaptive filter 311 performs filtering of the sound source signal using the generated acoustic
model 2005.
[0084]
Then, the first partial acoustic model generated by the first partial acoustic model adaptation unit
1401 is input to the first frequency band division filter 1402, and only the acoustic model of the
frequency band including the first resonance peak is extracted. Ru. On the other hand, the second
partial acoustic model input to the second partial acoustic model adaptation unit 1403 is input to
the second frequency band division filter 1404, and only the acoustic model of the frequency
band including the second and subsequent resonance peaks is extracted Be done.
[0085]
Thereafter, in the combining unit 1406, the first partial acoustic model of the frequency band
including the first resonance peak and the second partial acoustic model of the frequency band
including the second and subsequent resonance peaks are combined. This makes it possible to
generate an acoustic model corrected so as to suppress the resonance of each resonance peak.
[0086]
Since an acoustic model that appropriately represents each resonance peak can be constructed
by the process described above, the acoustic model can be applied to various applications such
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as removal of resonance characteristics.
[0087]
In the acoustic characteristic correction device 150 according to the present embodiment and
the modification, an example in which the external ear canal at the time of wearing the earphone
is generated as an acoustic model has been described.
With this system, the characteristics when the earphone is attached are intentionally added, and
the characteristics when the earphone is not attached are generated as an acoustic model, and
those with the characteristics when the earphone attached are removed are added and added
when the earphone is not attached. Acoustic characteristics can be realized.
[0088]
Furthermore, in the acoustic characteristic correction apparatus 150 according to the present
embodiment and the modification, it is possible to perform simple and flexible correction on the
resonance characteristic of the object to be measured having acoustic characteristics that are not
flat on the frequency axis. . Furthermore, since the present invention can be applied to objects
having adverse conditions and complex characteristics in terms of hardware resources etc., the
application range has been broadened.
[0089]
Assuming that the ear canal when wearing the earphones is a uniform acoustic tube with
countless resonance frequencies blocked by the earphones and tympanic membrane (wall) as
shown in FIG. 8, the resonance frequency harmful to the sense of hearing is removed It can be
difficult to do. On the other hand, in the present modification, since it is possible to construct an
acoustic model that appropriately represents each resonance peak, it is possible to appropriately
remove the acoustically harmful resonance frequency by generating a filter or the like based on
the acoustic model. .
[0090]
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23
Even when the acoustic model and the inverse filter model shown in the above-described
modified example are applied, the same effect as that of the first embodiment can be obtained.
[0091]
The acoustic characteristic correction apparatus 150 shown in FIG. 21 includes a CPU 2101, a
ROM (Read Only Memory) 2102, a RAM 2103, a sound source interface 2104, and a bus 2105
connecting these, and a normal computer is used. It has a hardware configuration.
[0092]
The acoustic characteristic correction program to be executed by the acoustic characteristic
correction device 150 according to the above-described embodiment is provided by being
incorporated in advance in the ROM 2102 or the like.
[0093]
The acoustic characteristic measurement program to be executed by the acoustic characteristic
correction program to be executed by the acoustic characteristic correction device 150 according
to the above-described embodiment is a CD-ROM, a flexible disk (FD , And may be provided by
being recorded on a computer-readable recording medium such as a CD-R, a DVD (Digital
Versatile Disk), or the like.
[0094]
Furthermore, an acoustic characteristic correction program executed by the acoustic
characteristic correction device 150 according to the above-described embodiment is stored on a
computer connected to a network such as the Internet and provided by being downloaded via the
network. You may.
The acoustic characteristic correction program executed by the acoustic characteristic correction
device 150 according to the above-described embodiment may be provided or distributed via a
network such as the Internet.
[0095]
The acoustic characteristic correction program executed by the acoustic characteristic correction
device 150 according to the embodiment described above has a module configuration including
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the above-described components. As an actual hardware, the CPU 2101 executes the acoustic
characteristic correction program from the ROM 2102 Is read out and executed to load the
above-described units onto the RAM 2103, and the above-described components are generated
on the RAM 2103.
[0096]
DESCRIPTION OF SYMBOLS 100 sound reproduction apparatus 110 mobile phone terminal 120
earphone 130 case part 150 sound characteristic correction apparatus 201 sound output unit
202 sound input unit 301 sound source input unit 302 sound source output mode processing
unit 303 electric / acoustic conversion unit 306 acoustic / electric conversion unit 307
Correction setting mode processing unit 308 Switching unit 311 Acoustic model adaptive filter
321 Measurement signal generating unit 322 Parameter specifying unit 323 Characteristic
specifying unit 324 Response data acquisition unit 330 Microphone 1401 Partial acoustic model
adaptation unit 1402 First frequency band division filter 1403 Second Partial acoustic model
adaptation unit 1404 second frequency band division filter 1406 combination unit 2101 CPU
2102 ROM 2103 RAM 2104 sound source interface 2105 bus
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