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DESCRIPTION JP2014168200

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DESCRIPTION JP2014168200
Abstract: [Problem] To provide a hearing aid capable of sufficiently suppressing the muffled
noise in the ear canal that is unpleasant for the user without adversely affecting the hearing aid
processing. A hearing aid according to the present invention includes an external microphone 2,
a hearing aid processing means 20 for performing a hearing aid process on an output signal of
the external microphone 2 to generate a signal s (n), and a signal u1 (n) = s (s). n) an earphone 4
which converts -y (n) into sound and outputs it to a space in the ear canal, an in-ear microphone
5 which converts sound traveling in the ear canal into an electric signal, and Signal processing
means including an adaptive filter 26 for adaptively estimating unnecessary components other
than the sound output from the earphone 4 based on a predetermined transfer function
corresponding to the path to the output side to generate a signal y (n) (21 to 26), and is
configured to remove the component of the booming sound d (n) from the aforementioned signal
s (n) based on the signal y (n). [Selected figure] Figure 2
Hearing aid and muddy sound suppression device
[0001]
The present invention relates to a hearing aid and a muddy sound suppression device having a
configuration capable of suppressing mumbling noise generated in the ear canal.
[0002]
A general hearing aid used by a moderate to severe deaf person is worn with the ear canal
sealed, and it is a problem that the user of the hearing aid has an unpleasant feeling of
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1
stagnation.
That is, when reaching the ear canal in which the self-voice and the stuttering sound (hereinafter
referred to as "the booming sound") transmitted in the ear canal are closed, the booming sound
unnaturally increases and gives the user a sense of discomfort (stagnation). Sometimes. As a
measure to eliminate such a feeling of stagnation, it is conceivable to use a structure in which a
hearing aid is provided with a vent, or an open type hearing aid that does not seal the ear canal.
There is a drawback that it is easy to return and inevitably causes howling to occur.
[0003]
Conventionally, a technology has been proposed for removing unnecessary components from a
desired signal by applying digital signal processing to an output signal of an in-ear microphone
provided on the side of the ear canal of a hearing aid (Patent Document 1, 2). For example, in
Patent Document 1, the sound in the ear canal is collected by the in-ear microphone, and the
output signal of the digital signal processor (signal after hearing aid processing) is controlled
based on the output signal of the in-ear microphone A hearing aid is disclosed. For example,
Patent Document 2 discloses a hearing aid that collects the sound of the ear canal by an in-ear
microphone and controls low-frequency components of the output signal of the in-ear
microphone to be fed back to the earphone.
[0004]
Japanese Patent Application Publication No. 2002-530034 US Patent No. 7477754
[0005]
However, there are various disadvantages in order to realize a configuration for removing the
unpleasant roaring sound for the user by applying the techniques disclosed in Patent Documents
1 and 2.
First, in the hearing aid disclosed in Patent Document 1, a process of removing unnecessary
components such as a booming sound is integrated with a normal hearing aid process. In this
case, since the hearing aid processing in the hearing aid is digital signal processing that adjusts
the level and frequency characteristics of the audio signal appropriately according to the
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2
characteristics of the user's hearing ability and the use environment, it is necessary to
incorporate processing to remove unnecessary components. A significant impact on the hearing
aid process can not be avoided, and the user may find that the adjustment of the hearing aid is
inadequate. Further, the hearing aid disclosed in Patent Document 2 is not preferable in that the
low frequency component of the normal sound signal necessary for the user is also suppressed
when the low frequency component of the booming sound is suppressed. Moreover, since the
transfer function of the path from the earphone to the in-ear microphone through the space in
the ear canal is not taken into consideration, it is difficult to obtain a sufficient effect of canceling
the muddy sound. As described above, according to the conventional hearing aid, there is a
problem that it is difficult for the user to sufficiently suppress unpleasant muddy sound without
greatly affecting the hearing aid processing when the hearing aid is attached.
[0006]
The present invention has been made to solve these problems, and a hearing aid that can
sufficiently suppress the muffled noise in the ear canal that is unpleasant for the user without
adversely affecting the hearing aid processing when the hearing aid is worn. Intended to be
provided.
[0007]
In order to solve the above problems, the hearing aid of the present invention is a hearing aid to
be attached to the external ear canal, for an external microphone (2) that converts external sound
into an electrical signal, and an output signal of the external microphone (2). Hearing aid
processing means (20) for performing a hearing aid process to generate a first signal (s (n)), and
a second signal (u1 (u (a)) generated based on the first signal (s (n)) n) an earphone (4) for
converting the sound into a sound and outputting it to the space in the external ear canal, and an
in-ear microphone provided facing the space in the external ear canal and converting the sound
transmitted through the external ear canal into an electrical signal Sound input to the in-ear
microphone (5) based on a predetermined transfer function corresponding to a path from the
input side of the earphone (4) to the output side of the in-ear microphone (5) From the earphone
(4) of e (n) Signal processing means (21 to 26) including an adaptive filter (26) for adaptively
estimating unnecessary components (d (n)) other than the sound to be forced to generate a third
signal (y (n)) , And the second signal obtained by adding a component for canceling the
unnecessary component (d (n)) to the first signal (s (n)) based on the third signal (y (n)). It is
characterized by generating (u1 (n)).
[0008]
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According to the hearing aid of the present invention, the sound output to the external ear canal
through the external microphone, the hearing aid processing means, and the earphone is input to
the in-ear microphone after adding unnecessary components such as booming noise in the space
in the external ear canal However, due to the feedback operation of the adaptive filter of the
signal processing means, unnecessary components can be canceled out in the space in the ear
canal based on the adaptively estimated unnecessary components.
At this time, even if a signal having a phase opposite to that of the mumbling sound sampled
simply by the in-ear microphone is generated and fed back to the sound output from the
earphone, the path from the input of the earphone to the output of the in-ear microphone
Although the muffled sound can not be canceled appropriately because it is affected by the
transfer function of the hearing noise, according to the present invention, the muffled sound is
transmitted along the path of the aforementioned transfer function using an adaptive filter
provided separately from the hearing aid processing means. It is possible to cancel out the
muffled sound in the space in the ear canal precisely by estimating the signal when it is
propagated.
[0009]
In the hearing aid of the present invention, in addition to the adaptive filter, the signal processing
means subtracts the third signal from the first signal to output the second signal; and A first
estimation filter that receives a second signal and outputs a fourth signal estimated based on the
predetermined transfer function, and subtracts the fourth signal from the output signal of the inear microphone A second subtractor that outputs a fifth signal that is an input signal of the
adaptive filter, and the fifth signal that is input, and outputs a sixth signal estimated based on the
predetermined transfer function And a coefficient updating unit that adaptively updates the filter
coefficient of the adaptive filter based on the second estimation filter and the sixth signal and the
output signal of the in-ear microphone.
With such a configuration, using the first estimation filter and the second subtractor, the fifth
signal including only the component of the muffled sound is input to the adaptive filter, and the
second estimation filter and the coefficient updating unit are used. Thus, the filter coefficients of
the adaptive filter can be adaptively updated, and finally the first subtractor can be used to add a
component that cancels the muffled sound to the necessary sound signal.
[0010]
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In the hearing aid of the present invention, the coefficient updating unit may be configured to
update the filter coefficient of the adaptive filter in accordance with a Least Mean Square (LMS)
algorithm. The basis of the LMS algorithm is the steepest descent method, in which the filter
coefficients are updated so as to minimize the mean square error, and the convergence speed can
be improved with a simple configuration.
[0011]
In the hearing aid of the present invention, the first estimation filter and the second estimation
filter are a transfer function R (z) representing the characteristic of the earphone, and the output
side of the earphone to the input side of the in-ear microphone It can be expressed as P (z) = R (z)
· F (z) · M (z) using the transfer function F (z) and the transfer function M (z) representing the
characteristics of the in-ear microphone It is configured to have a transfer function P (z). In this
case, R (z) and M (z) constituting the transfer function P (z) can be accurately determined based
on the characteristics of the earphone and the in-ear microphone, and F (z) related to the sound
propagation in the ear canal Well-known techniques for determining
[0012]
Further, in order to solve the above-mentioned problems, the booming noise suppression device
of the present invention is a booming noise suppression device having a housing mounted on an
ear canal, wherein an input signal is a first signal, An earphone for converting a second signal
generated on the basis of the signal into a sound and outputting the sound to a space in the ear
canal, and a space facing the space in the ear canal, wherein the sound transmitted through the
ear canal is an electric signal Of the sounds input to the in-ear microphone based on the in-ear
microphone to be converted and at least the transfer function corresponding to the path from the
input side of the earphone to the output side of the in-ear microphone And signal processing
means including an adaptive filter that adaptively estimates unnecessary components other than
the sound to generate a third signal, and the unnecessary components are removed from the first
signal based on the third signal. It is characterized in that to generate the second signal. Thus, the
present invention is not limited to hearing aids, but can be applied to various devices attached to
the ear canal of the user, and the user can sufficiently suppress unpleasant unpleasant noise
when the devices are attached. .
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[0013]
As described above, according to the present invention, when the hearing aid or the like is
attached and the external auditory canal is substantially sealed, the user feels stagnant
(discomfort) due to the roaring noise generated in the external ear canal. Can be prevented. In
this case, since the processing for canceling the booming sound is executed separately from the
hearing aid processing by the signal processing means including the adaptive filter, the hearing
aid processing does not affect the adjustment of the hearing aid. In addition, since the booming
sound can be canceled by appropriately considering the transfer function of the path from the
earphone to the in-ear microphone through the inside of the ear canal, the effect of canceling the
booming sound is improved, and a hearing aid of higher quality is realized. It can be realized.
[0014]
It is a block diagram which shows the schematic structure of the hearing aid of this embodiment.
In the hearing aid of this embodiment, it is a block diagram which shows the example of a
concrete structure relevant to digital signal processing. It is a figure which shows the example of
a structure of a general filtered-x LMS. It is a conceptual diagram when simplifying the structure
of this embodiment and applying it to the structure of filtered-x LMS of FIG. It is a figure
explaining the effect of the hearing aid to which the present invention is applied, and is a figure
showing the time waveform of input sound pressure, and the example of the time waveform of
the simulation signal of muddy sound. In the case where the configuration of the present
embodiment is not adopted and the case where the configuration of the present embodiment is
adopted by using the simulation signal of the booming sound in FIG. 5, the time waveform of the
sound pressure in the ear canal is compared and shown. FIG. It is a figure which shows the
structural example of the hearing aid which concerns on a 1st modification. It is a figure which
shows the structural example of the hearing aid which concerns on a 2nd modification.
[0015]
Hereinafter, embodiments of the present invention will be described with reference to the
attached drawings. The following embodiment is an example in which the present invention is
applied to a hearing aid attached to the ear canal of a user.
[0016]
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FIG. 1 is a block diagram showing a schematic configuration of the hearing aid of the present
embodiment. As shown in FIG. 1, the hearing aid of the present embodiment includes an external
microphone 2, a DSP (Digital Signal Processor) 3, and an earphone 4 in a case 1 as a housing
having a shape that can be inserted into the user's ear. , The in-ear microphone 5, the battery
holder 6, and the button battery 7 in the inside thereof. The case 1 comprises a face plate 1 a
facing the external space of the ear and a shell 1 b disposed along the ear canal 10. An external
microphone 2 is attached to the face plate 1a through a sound port, and an earphone 4 and an
intra-ear microphone 5 are provided in a portion of the shell 1b facing the space S between the
ear canal 10 and the eardrum 11 at the back. Each is attached via a sound port. Although not
shown in FIG. 1, the shell 1 b of the case 1 may be provided with a vent that communicates the
outside with the external ear canal 10. In this case, the role of the vent discharges the moisture
of the ear canal 10 to the outside and also has the effect of suppressing the booming noise, so
when this is insufficient, the effect of applying the present invention can be expected.
[0017]
In the configuration of FIG. 1, the external microphone 2 collects the sound transmitted from the
external space and converts it into an electrical signal. On the other hand, the in-ear microphone
5 collects the sound transmitted from the space S in the ear canal 10 and converts it into an
electric signal. Further, the earphone 4 adjacent to the in-ear microphone 5 converts an electric
signal into a sound and outputs the sound to the space S described above. The earphone 4 and
the in-ear microphone 5 located on the space S side in the ear canal 10 are members essential for
canceling out the muffled sound in the ear canal 10. That is, when the opening is blocked by the
case 1 when the hearing aid user's own voice or stuttering is transmitted to the ear canal 10,
these sounds can be loudly heard (a booming noise), which makes the user uncomfortable. There
is a risk of giving a feeling of stagnation. As a countermeasure therefor, in the present
embodiment, the process of canceling the muffled sound is executed in the hearing aid, but the
details will be described later.
[0018]
The DSP 3 performs digital signal processing including cancellation processing of the abovementioned booming sound on the electric signals respectively input from the external
microphone 2 and the in-ear microphone 5 and the electric signals output to the earphone 4.
Specific processing will be described later. The button battery 7 held inside the battery holder 6
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supplies power to each component of the hearing aid. The button battery 7 is configured to be
replaceable by opening and closing the opening of the battery holder 6 as necessary.
[0019]
Next, FIG. 2 is a block diagram showing a specific configuration example related to digital signal
processing in the hearing aid of the present embodiment. As shown in FIG. 2, the functional
elements of the DSP 3 include a hearing aid processing unit 20, two subtractors 21 and 22, two
estimation filters 23 and 24, a coefficient updating unit 25, and an adaptive filter 26. . Among
these, the functional elements other than the hearing aid processing unit 20 integrally function
as the signal processing means of the present invention. Further, in FIG. 2, the external
microphone 2, the earphone 4 and the in-ear microphone 5 in FIG. 1 are respectively shown, and
the sound reaching the in-ear microphone 5 from the earphone 4 in the space S in the external
ear canal 10 Each transmission path is shown.
[0020]
First, the output signal of the external microphone 2 is input to the hearing aid processor 20. The
hearing aid processing unit 20 is a hearing aid processing means for performing predetermined
hearing aid processing individually set for each user with respect to the output signal of the
external microphone 2, and generates a signal s (n). Hearing aid processing performed by the
hearing aid processing unit 20 includes, for example, multiband compression on the output
signal of the external microphone 2, noise reduction, tone control, volume control, output
restriction processing, etc. It is possible to apply various processes in accordance with Although
not shown in FIG. 2, an AD converter for converting an analog signal into a digital signal is
provided on the output side of the external microphone 2 and the in-ear microphone 5, and a
digital signal is provided on the input side of the earphone 4. It is necessary to provide a DA
converter that converts a signal into an analog signal.
[0021]
The signal s (n) output from the hearing aid processor 20 is input to a subtractor 21 (a first
subtractor of the present invention). The subtractor 21 subtracts the output signal y (n) of the
adaptive filter 26 from the signal s (n) to generate a signal u1 (n). In this case, the signal u1 (n) is
expressed by the following equation (1).
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[0022]
u1 (n) = s (n)-y (n) (1) The adaptive filter 26 is a filter that adaptively generates an output signal
y (n) for canceling a booming sound, and the details will be described later. . The signal u1 (n)
output from the subtractor 21 is input to each of the earphone 4 and the estimation filter 23. As
described in FIG. 1, the sound output from the earphone 4 propagates through the space S in the
ear canal 10 to reach the tympanic membrane 11 and is also input to the in-ear microphone 5. At
this time, a roaring sound reaching the space S is input to the in-ear microphone 5 through a
path different from the sound output from the earphone 4.
[0023]
Here, the transfer function of the earphone 4 is R (z), the transfer function of the path from the
output side of the earphone 4 to the input side of the in-ear microphone 5 is F (z), and the
transfer function of the in-ear microphone 5 is M (z) Each shall be represented as In this case, the
above-mentioned signal u1 (n) is converted to the output sound u2 (n) via the transfer function R
(z) and the transfer function F (z). Then, when the output sound u2 (n) from the earphone 4 and
the booming sound d (n) are input to the in-ear microphone 5 as a synthesized sound e (n) as a
result of being added by the virtual adder 12 I can think of it. In this case, the synthetic sound e
(n) is expressed by the following equation (2).
[0024]
e (n) = u2 (n) + d (n) (2) The above-mentioned synthesized sound e (n) is converted to a signal e
′ (n) via the transfer function M (z) of the in-ear microphone 5 Then, they are input to the
subtractor 22 and the coefficient updating unit 25 respectively. On the other hand, the abovedescribed estimation filter 23 (the first estimation filter of the present invention) is an estimated
signal u1 ′ (n in the case where it is assumed that the signal u1 (n) propagates from the
earphone 4 through the in-ear microphone 5). ) Is a filter that generates Therefore, the transfer
function P (z) of the estimation filter 23 is expressed by the following equation (3) using the
above-described transfer functions R (z), F (z) and M (z).
[0025]
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P (z) = R (z) F (z) M (z) (3) The estimated signal u1 '(n) output from the estimation filter 23 is
input to the subtractor 22. The subtractor 22 (the second subtractor of the present invention)
subtracts the estimated signal u1 ′ (n) from the above-mentioned signal e ′ (n) output from the
in-ear microphone 5, and inputs the signal to the adaptive filter 26. Generate a signal x (n). In
this case, the input signal x (n) is expressed by the following equation (4).
[0026]
x (n) = e '(n) -u1' (n) (4) Meanwhile, this input signal x (n) is also input to the estimation filter 24
in addition to the adaptive filter 26. The estimation filter 24 (the second estimation filter of the
present invention) estimates the estimated signal x ′ (n) when it is assumed that the input signal
x (n) propagates from the earphone 4 through the in-ear microphone 5. It is a filter to generate.
The estimation filter 23 has the same transfer function P (z) as the equation (3).
[0027]
Thus, the two estimation filters 23, 24 have equal transfer functions P (z) = R (z) F (z) M (z). On
the other hand, the estimated signal x ′ (n) output from the estimation filter 24 is input to the
coefficient updating unit 25. The coefficient updating unit 25 adaptively updates filter
coefficients used for the operation of the adaptive filter 26 in accordance with a Least Mean
Square (LMS) algorithm. That is, the coefficient updating unit 25 receives the above signal e ′
(n) and the estimated signal x ′ (n), and calculates a filter coefficient that minimizes the mean
square of the signal e ′ (n). .
[0028]
The adaptive filter 26 performs a filter operation based on the transfer function C (z) on the
input signal x (n) based on the filter coefficient determined by the coefficient updating unit 25 to
generate an output signal y (n). . At this time, due to the operation of the estimation filter 23 and
the subtracter 22, the input signal x (n) is a signal obtained by estimating the booming noise.
Therefore, the output signal y (n) of the adaptive filter 26 has a transfer function R (z) from the
earphone 4 to the in-ear microphone 5 by interposing the estimation filter 24, the coefficient
updating unit 25 and the adaptive filter 26. It is a signal including a booming sound in a state in
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which the influence of F (z) is taken into consideration. In addition, as the adaptive filter 26, for
example, FIR (Finite Impulse Response) having a predetermined number of taps (for example, 32
taps) can be used.
[0029]
As described above, by subtracting the output signal y (n) of the adaptive filter 26 from the
signal s (n) output from the hearing aid processing unit 20, the component of the muffled sound
reflects the influence of the transfer function. A signal u1 (n) can be generated to which a signal
to be effectively canceled is added, and this can be output as a sound from the earphone 4.
Therefore, the user wearing the hearing aid can hear a comfortable sound in the ear canal 10 in
which the muffled sound is sufficiently suppressed. In this case, as can be seen from FIG. 2, the
entire signal processing means necessary for canceling the muffled sound is disposed in the
subsequent stage of the hearing aid processing unit 20 in the DSP 3, which adversely affects the
hearing aid processing of the hearing aid processing unit 20. You can cancel the booming noise
without giving
[0030]
Here, the adaptive filter 26 of FIG. 2 and the periphery thereof have a configuration of so-called
filtered-x LMS. FIG. 3 shows an example of a typical filtered-x LMS configuration. That is, in FIG.
3, an adaptive filter 30 which receives an input signal x (n) and outputs an output signal y (n),
and an error signal e (an output signal y (n) subtracted from the signal d (n) In addition to the
LMS coefficient updating unit 31 for obtaining the updated value ΔWn of the filter coefficient
Wn so as to minimize the root mean square of n), the filter 32 is placed before the LMS
coefficient updating unit 31 to which the input signal x (n) is input. It is inserted.
[0031]
On the other hand, FIG. 4 is a conceptual diagram when the configuration of the present
embodiment (FIG. 2) is simplified and applied to the configuration of the filtered-x LMS of FIG. In
FIG. 4, assuming a basic signal path in which the components in FIG. 2 are omitted, the transfer
function M (z) of the in-ear microphone 5 is also ignored. In FIG. 4, the adaptive filter 26 and the
coefficient updating unit 25 correspond to the adaptive filter 30 and the LMS coefficient
updating unit 31 in FIG. 3, respectively. Then, the filter 32 having the transfer function A (z) is
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provided similarly to the configuration of FIG. 3, but in addition to this, it has the transfer
function A (z) inserted in the output signal y (n) It differs from FIG. 3 in that a filter 33 is
provided. This filter 33 corresponds to the path from the earphone 4 to the adder 12 in FIG. 2,
and assumes that the output signal of the filter 33 is synthesized with the booming sound. The
transfer function A (z) of the filters 32 and 33 can be expressed as A (z) = R (z) F (z).
[0032]
In general, it is known that if a filter is inserted at the output of the adaptive filter 26, the
adaptive filter 26 does not operate properly. However, in the configuration of FIG. 4, the
positions of the adaptive filter 26 and the filter 33 can be interchanged in consideration of the
linearity of the system. Also, in the path after the input signal x (n) is branched, the form in which
the two filters 32 and 33 are inserted in parallel is one with a transfer function A (z), considering
the linearity of the system Is inserted before the branching of the input signal x (n), and the path
is branched to the adaptive filter 26 and the coefficient updating unit 25 at a position after that.
Therefore, in the configuration of the present embodiment, it can be considered that the
estimation filter 24 ensures proper operation of the adaptive filter 26.
[0033]
On the other hand, in FIG. 4, the in-ear microphone 5 shown in FIG. 2 is not taken into
consideration, but the transfer function M (z) of the in-ear microphone 5 is actually in the path of
the error signal e (n) in FIG. The inserted configuration is assumed. In this case, for the normal
operation of the adaptive filter 26, a path from the input signal x (n) to the coefficient updating
unit 25 via the adaptive filter 26 and the filter 33, and a filter 32 from the input signal x (n). It is
premised that the relative phase delay is only a phase delay due to the adaptive filter 26 between
the path leading to the coefficient updating unit 25 via. Here, assuming that the phase delay of
each of the two filters 32 and 33 having the transfer function A (z) is τA and the phase delay of
the transfer function M (z) is τM, the adaptive filter 26 of the former path is The phase delay
excluding the phase delay due to V.sub.A is .tau.A + .tau.M, and the phase delay of the latter path
is .tau.A. Therefore, in order to eliminate the phase delay, the transfer function of the filter 32
may be A (z) M (z) = R (z) F (z) M (z), and the estimation filter 24 corresponding to the filter 32. It
can be seen that (Figure 2) satisfies this relationship. However, if the in-ear microphone 5 has a
flat frequency characteristic, the phase delay does not matter, so the transfer function of the
estimation filter 24 may be set to A (z).
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[0034]
Next, with reference to FIGS. 5 and 6, the effect of the hearing aid to which the present invention
is applied will be described. In FIG. 5 and FIG. 6, simulation was performed under predetermined
conditions with respect to the configuration example of FIG. 2 to confirm the effect that booming
noise is actually suppressed. First, FIG. 5 (A) shows an example of the time waveform of the
sound pressure input to the external microphone 2, and FIG. 5 (B) is applied to the ear canal 10
based on the audio signal of FIG. 5 (A). It shows a time waveform of a signal generated by
simulating the dazzling sound d (n). For example, by applying a low pass filter to a predetermined
audio signal recorded, it is possible to generate a simulation signal of the booming sound d (n)
shown in FIG. 5 (B). On the other hand, FIG. 6A shows the inside of the ear canal 10 in the case
where the configuration of the present embodiment is not adopted using the simulation signal of
the booming sound d (n) of FIG. 5B for comparison with the present embodiment. Shows the time
waveform of the sound pressure at. Also, FIG. 6 (B) shows the sound pressure time in the ear
canal 10 when the configuration of the present embodiment (FIG. 2) is adopted using the
simulation signal of the booming sound d (n) of FIG. 5 (B). The waveform is shown. As apparent
from comparison of FIGS. 6A and 6B, it can be seen that the magnitude of the booming sound d
(n) can be sufficiently suppressed by adopting the configuration of the present embodiment.
[0035]
As mentioned above, although the hearing aid of this embodiment was demonstrated using FIGS.
1-6, the application object of this invention is not limited to a hearing aid. That is, the present
invention can be applied to various devices provided with a housing attached to the ear canal and
a configuration for outputting sound from the earphone to the ear canal. For example, the
present invention can be applied to an earphone device for audio. For example, in FIG. 2, without
providing the hearing aid processing unit 20, an input unit to which an audio signal output from
the audio apparatus is input is provided, and the signal output from this input unit is the signal s
(n) of FIG. The present invention can be applied as Further, without providing this input means,
an inverting amplifier for inverting the output signal y (n) of the adaptive filter 26 is provided,
and the output thereof is the signal u1 (n) of FIG. The present invention can be applied to ear
plugs that have Besides the above, the present invention can be applied as a muffled sound
suppression device to various devices that can be attached to the ear canal.
[0036]
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Furthermore, the present invention is not limited to the above-described embodiment, and there
are various modifications. For example, FIG. 7 shows a configuration example of a hearing aid
according to a first modification. As shown in FIG. 7, in the first modification, a transfer function
setting unit 27 is provided which sets the transfer function P (z) of each of the estimation filters
23 and 24 to the configuration of FIG. According to the first modification, the transfer function
setting unit 27 is appropriately set in accordance with the shape and size of the user's ear canal
10 and the tympanic membrane 11, and a desired transfer function P (z Can be given. On the
other hand, FIG. 8 shows a configuration example of a hearing aid according to a second
modification. As shown in FIG. 8, in the second modification, the estimation filter 23 is replaced
with the adaptive filter 23 a in the configuration of FIG. 2, and the coefficient updating unit 28
associated with the adaptive filter 23 a is provided. The transfer function P (z) obtained by the
adaptive filter 23 a is copied to the estimation filter 24. The functions of the adaptive filter 23a
and the coefficient updating unit 28 are as described using the adaptive filter 26 and the
coefficient updating unit 25 in FIG. According to the second modification, the accuracy of the
transfer function P (z) used in the adaptive filter 23a and the estimation filter 24 can be
enhanced, and the cancellation effect of the booming sound can be improved, and the
performance is improved even if the transfer function F (z) changes. You can keep
[0037]
As mentioned above, although the contents of the present invention were concretely explained
based on this embodiment, the present invention is not limited to each above-mentioned
embodiment, A various change can be given in the range which does not deviate from the
summary. . For example, in FIG. 2, regarding the configuration of the subsequent stage of the
hearing aid processing unit 20, a transfer function corresponding to a path from the input side of
the earphone 4 to the output side of the in-ear microphone 5 is considered. On the premise of the
above, various configurations can be adopted to remove unnecessary components including a
booming noise.
[0038]
DESCRIPTION OF SYMBOLS 1 ... Case 2 ... External microphone 3 ... DSP 4 ... Earphone 5 ... Ear
microphone 6 ... Battery holder 7 ... Button battery 10 ... Ear canal 11 ... Eardrum 12 ... Adder 20
... Hearing processing part 21, 22 ... Subtractor 23, 24 ... estimation filter 25, 28 ... coefficient
update unit 26, 23a ... adaptive filter 27 ... transfer function setting unit
11-04-2019
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