JP4010968B2 - Hearing aid with howling suppression - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hearing aid having a function of suppressing howling caused by an acoustic feedback path formed between an earphone and a microphone of the hearing aid.
[0002]
[Prior art]
As a method of suppressing howling caused by an acoustic feedback path (leakage path) formed between an earphone and a microphone in a conventional programmable hearing aid, when a howling occurs, the peak value is detected and howling is performed using a notch filter. A method for removing the peak is the mainstream (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP-A-5-207596 [0004]
[Problems to be solved by the invention]
However, since the howling suppression method using the notch filter suppresses howling with a local high gain, if the howling frequency does not match, it does not have a howling suppression effect and also has an adverse effect on the frequency characteristics of the hearing aid processing. .
In addition, howling frequency detection accuracy and howling suppression with a notch filter may cause howling at a frequency other than the suppressed frequency. It has become difficult.
Further, in such a howling suppression method using a notch filter, since howling is performed after howling occurs, howling always occurs.
[0005]
In-ear hearing aids, the ear-type hearing aid is equipped with a conduit for balancing the auricular side-external pressure and the external auditory canal side-intra-ear pressure, which is called "vent", in order to suppress the increase in the pressure in the ear canal when the hearing aid is worn by the wearer. In some cases, it is formed in advance from the ear canal side to the pinna side.
When making adjustments for highly deaf people, it is generally necessary to first increase the acoustic output and gain level of the hearing aid to the hearing level of the wearer without causing howling.
However, in an in-ear hearing aid having a “vent”, sound leaks from this pre-formed duct, and howling easily occurs.
[0006]
The present invention has been made in view of such problems of the prior art, and the object of the present invention is to provide a howling suppression function capable of performing howling suppression processing according to the wearing condition of a hearing aid. It is intended to provide a hearing aid.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problem, an invention according to claim 1 is directed to a hearing aid including an external microphone, a hearing aid processing unit, and an earphone, and an in-ear microphone that is provided in the vicinity of the earphone to detect an output change of the earphone. Sound leakage component estimation means for estimating the sound leakage component input to the external microphone from the output signal and the input signal of the earphone via the acoustic feedback path, and the sound leakage component estimated by the sound leakage component estimation means to the outside A howling suppression processing means for subtracting from the output signal of the microphone and outputting to the hearing aid processing section is provided , and the acoustic leakage component estimating means is configured to output the earphone output signal and the input signal of the in-ear microphone by forming an acoustic feedback path. From the change of the internal transfer function that gives the relationship to the That gives the relationship between the acoustic leak component estimates the leakage transfer function, and calculates the acoustic leakage component.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a schematic diagram showing the wearing state of the in-ear hearing aid, FIG. 2 is a block diagram of a hearing aid having a howling suppression function according to the present invention, and FIG. 3 is a block diagram of acoustic leakage component estimation means. .
[0010]
When the in-ear hearing aid 1 is worn, an acoustic feedback path (leakage path) 3 may be formed between the hearing aid 1 and the external auditory canal 2 by jaw movement such as mastication as shown in FIG.
Further, the wearer may preliminarily form a conduit from the outer ear side to the outer ear canal side in order to balance the increase in the external ear canal pressure that occurs during insertion with the external atmospheric pressure, and this is the acoustic feedback path 3. In some cases.
When such an acoustic feedback path 3 is formed, howling generally occurs. 4 is an auricle and 5 is an eardrum.
[0011]
As shown in FIG. 2, a hearing aid 1 having a howling suppression function according to the present invention includes an external microphone 6 that detects external sound and converts it into an electrical signal, and a hearing aid processing unit 7 that processes the output of the external microphone 6 and the like. And an earphone 8 for electroacoustic conversion of the output of the hearing aid processing unit 7 to emit sound in the ear canal 2, an in-ear microphone 9 provided in the vicinity of the earphone 8, and an acoustic leakage component estimation for estimating an acoustic leakage component. Means 10 and howling suppression processing means 11 for outputting a signal that suppresses howling to the hearing aid processing unit 7.
[0012]
G (s) is an actual internal transfer function that gives the relationship between the output signal of the earphone 8 and the input signal of the in-ear microphone 9 due to the acoustic leakage component formed by the external auditory canal 2 and the acoustic feedback path 3, and H (s ) Is an actual leakage transfer function that gives the relationship between the output signal of the earphone 8 by the external auditory canal 2, the acoustic feedback path 3, and the pinna 4 and the input signal (acoustic leakage component) of the external microphone 6. G (s) and H (s) are transfer functions representing the input / output ratio in the s region (Laplace transform region).
[0013]
The in-ear microphone 9 is emitted from the earphone 8 to detect an acoustic leak component that returns to the external microphone 6 through the acoustic feedback path 3 formed between the earphone 8 and the external microphone 6 shown in FIG. Detect sound output.
[0014]
The acoustic leakage component estimation means 10 estimates the acoustic leakage component input to the external microphone 6 via the acoustic feedback path 3 from the input signal of the earphone 8 and the output signal of the in-ear microphone 9.
[0015]
The howling suppression processing unit 11 subtracts the sound leakage component calculated by the sound leakage component estimation unit 10 from the output signal of the external microphone 6 to obtain an input signal to the hearing aid processing unit 7.
[0016]
As shown in FIG. 3, the acoustic leak component estimating means 10 includes a leak-free internal transfer function setting unit 12, an internal transfer function estimating unit 13, an estimated internal transfer function setting unit 14, and leak transmission. It comprises a function estimation unit 15 and an estimated leakage transfer function setting unit 16.
[0017]
The internal transfer function setting unit 12 without leakage gives a relationship between the output signal of the earphone 8 and the input signal of the in-ear microphone 9 in a state where the acoustic feedback path 3 is not formed and there is no acoustic leakage component. An internal transfer function G0 (s) with no leakage is set. The internal transfer function G0 (s) having no leakage is obtained and set in advance.
[0018]
The internal transfer function calculation unit 13 calculates a calculated internal transfer function G ′ (s) from the input signal of the earphone 8 and the output signal of the in-ear microphone 9. The calculated internal transfer function setting unit 14 sets the calculated internal transfer function G ′ (s) calculated by the internal transfer function calculating unit 13.
[0019]
The leakage transfer function estimation unit 15 determines the ear from the difference between the output signals of the internal transfer function G0 (s) and the calculated internal transfer function G ′ (s) without any leakage when the input signal of the earphone 8 is an input signal. An estimated leakage transfer function H ′ (s) corresponding to the frequency response of the acoustic leakage component viewed from the inner microphone 9 is calculated.
[0020]
Here, since the acoustic leak component detected by the in-ear microphone 9 and the external microphone 6 corresponds to the peak in the frequency characteristic, the estimated leak transfer function H ′ (s) is obtained from the in-ear microphone 9. It can be calculated by paying attention to the frequency response of the seen acoustic leakage component.
[0021]
The estimated leakage transfer function setting unit 16 sets the estimated leakage transfer function H ′ (s) calculated by the leakage transfer function estimating unit 15. The output signal of the estimated leakage transfer function H ′ (s) when the input signal of the earphone 8 is used as an input signal becomes an acoustic leakage component viewed from the in-ear microphone 9.
[0022]
The operation of the hearing aid 1 having the above-configured howling suppression function according to the present invention will be described.
As shown in FIG. 1, when an acoustic signal is steadily output from the earphone 8 in a state where the acoustic feedback path 3 is formed between the hearing aid 1 and the external auditory canal 2, the sound generally passes through the acoustic feedback path 3. The leakage component is input to the external microphone 6 to generate howling. However, the hearing aid 1 having the howling suppression function according to the present invention operates as follows to suppress howling.
[0023]
First, when an acoustic signal is constantly output from the earphone 8, the internal transfer function calculation unit 13 calculates a calculated internal transfer function G ′ (s) from the input signal of the earphone 8 and the output signal of the in-ear microphone 9. The calculated internal transfer function setting unit 14 sets the calculated internal transfer function G ′ (s) calculated by the internal transfer function calculating unit 13.
[0024]
Next, the leakage transfer function estimating unit 15 calculates the output signal of the internal transfer function G0 (s) set in advance and the output signal of the calculated internal transfer function G ′ (s) set by the calculated internal transfer function setting unit 14. From the difference, an estimated leakage transfer function H ′ (s) corresponding to the frequency response of the acoustic leakage component viewed from the in-ear microphone 9 is calculated, and the estimated leakage transfer function setting unit 16 includes a leakage transfer function estimation unit. The estimated leakage transfer function H ′ (s) calculated in 15 is set.
[0025]
Next, the estimated leakage transfer function setting unit 16 inputs an input signal of the earphone 8 and outputs an acoustic leakage component viewed from the in-ear microphone 9. The acoustic leakage component output by the estimated leakage transfer function setting unit 16 is input to the howling suppression processing means 11. Then, the howling suppression processing means 11 subtracts the acoustic leak component from the output signal of the external microphone 6. Then, a signal obtained by subtracting the acoustic leakage component from the output signal of the external microphone 6 becomes an input signal of the hearing aid processing unit 7.
[0026]
Therefore, in a case where an acoustic signal is steadily output from the earphone 8 in a state where the acoustic feedback path 3 is formed, howling that occurs when an acoustic leakage component that has passed through the acoustic feedback path 3 is input to the external microphone 6. Can be suppressed.
[0027]
Further, a howling suppression effect can be obtained with a vented hearing aid by a similar method.
[0028]
【The invention's effect】
As described above, according to the present invention, it is possible to perform howling suppression processing that does not degrade the frequency characteristics of hearing aid processing according to the wearing situation of the hearing aid.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the wearing state of an in-ear hearing aid. FIG. 2 is a block diagram of a hearing aid having a howling suppression function according to the present invention. FIG. 3 is a block diagram of acoustic leakage component estimation means. ]
DESCRIPTION OF SYMBOLS 1 ... Hearing aid, 2 ... External ear canal, 3 ... Acoustic feedback path, 6 ... External microphone, 7 ... Hearing aid processing part, 8 ... Earphone, 9 ... In-ear microphone, 10 ... Acoustic leak component estimation means, 11 ... Howling suppression processing means .

Claims (1)

In a hearing aid comprising an external microphone, a hearing aid processing unit, and an earphone, an in-ear microphone that is provided in the vicinity of the earphone to detect an output change of the earphone, and an external signal through the acoustic feedback path from the output signal of the in-ear microphone and the input signal of the earphone Sound leakage component estimation means for estimating the sound leakage component input to the microphone, and the sound leakage component estimated by the sound leakage component estimation means are subtracted from the output signal of the external microphone and output to the hearing aid processor. The acoustic leakage component estimating means is provided with acoustic feedback from a change in an internal transfer function that gives a relationship between an output signal of an earphone and an input signal of an in-ear microphone due to formation of an acoustic feedback path. A leakage transfer function that gives the relationship between the output signal of the earphone by the path and the acoustic leakage component input to the external microphone. Estimating a, with a howling suppression function and calculates the acoustic leakage component hearing aid.

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