JP3794881B2 - Hearing aid - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hearing aid apparatus that can listen to sound clearly in consideration of the quality of environmental noise.
[0002]
[Prior art]
The noise present in the environment of use has a great influence on the hearing ability of the hearing aid wearer and the comfort of the output sound.
In order to solve this problem, a so-called non-linear amplification hearing aid (nonlinear hearing aid) in which an automatic gain limiting circuit (AGC circuit) is provided in the hearing aid and the acoustic gain or the like is appropriately adjusted according to the level of the input signal by the automatic gain limiting circuit. ) Has been proposed.
[0003]
The non-linear amplification hearing aid has an input / output characteristic that has a large gain for small sounds and a small gain for loud sounds, so a small input level that exists outside the audible area of the hearing impaired person is amplified in the audible area. At the same time, it is said that an unpleasant loud sound is suppressed without being amplified, and it is often said that the user's discomfort can be reduced in a noisy environment.
[0004]
[Problems to be solved by the invention]
However, the non-linear amplification hearing aid is easy to hear in the presence of environmental noise that is above a certain level and has a high degree of stationaryness, but in a good listening environment where there is almost no noise, the hearing aid follows the power fluctuation of the sound. The sound gain of the sound will change in a short time, so when listening to words deteriorates or when there is no voice, there is a problem that this noise is emphasized if the overall noise level is low .
Here, the stationarity is a scale representing a short-time fluctuation in power, and there is little power fluctuation like an air conditioner, and stationary noise has a high stationarity. In addition, the stationary degree is low in the noise in which the power fluctuates violently like a sheet metal factory.
[0005]
Nonlinear amplification hearing aids are better under low stationary noise levels, but linear amplification hearing aids are considered better under high stationary noise levels, but there are no analyzers that can measure this “steadiness level”. Moreover, there was no hearing aid that adaptively changes the characteristics according to such a scale.
[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 clearly hear the sound to be listened to regardless of the quality of the environmental noise. It is intended to provide a hearing aid device.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 includes an external sound detecting means for outputting an electric signal corresponding to an external sound, a signal processing means for processing an output signal of the external sound detecting means, and the signal processing means. In the hearing aid device comprising sound output means for converting the output signal of the sound into the sound signal, the signal processing means detects the stationary degree of noise included in the external sound from the signal output from the external sound detection means at a predetermined time interval. Stationary degree detection means, input / output characteristic processing means for compressing and amplifying the output signal of the external sound detection means, and compression amplification characteristic parameter table storing compression amplification characteristic parameters suitable for a hearing aid wearer, the stationarity detection The input / output characteristic of the input / output characteristic processing means is determined based on the compression amplification characteristic parameter corresponding to the stationary degree output from the means.
[0008]
The invention according to claim 2 is the hearing aid according to claim 1, wherein the compression amplification characteristic parameter is a compression ratio.
[0009]
The invention according to claim 3 is the hearing aid according to claim 1, wherein the compression amplification characteristic parameter is a knee point.
[0010]
According to a fourth aspect of the present invention, in the hearing aid device according to the first aspect, the compression amplification characteristic parameter is a linear gain.
[0011]
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 block diagram of the hearing aid according to the present invention, FIG. 2 is an explanatory diagram regarding frame division processing, FIG. 3 is an input / output characteristic diagram showing the relationship between the input sound pressure level and the output sound pressure level, and FIG. Is an input / output characteristic table, FIG. 5 is a flowchart showing the operation of the hearing aid according to the present invention, FIGS. 6 to 8 are frequency distribution diagrams used to explain the operation of the hearing aid, and FIG. 9 is another embodiment of the hearing aid. It is a frequency distribution figure with which it uses for description.
[0012]
As shown in FIG. 1, the hearing aid according to the present invention includes an external sound detection unit 1, a signal processing unit 2, and an output unit 3.
The external sound detection unit 1 includes a microphone 1a that detects an external sound and converts it into an electrical signal, and an A / D converter 1b that converts the output voltage of the microphone 1a into a digital signal. Output digital data based.
[0013]
The signal processing unit 2 includes an input / output characteristic processing unit 2a, a frame memory 2b, an average effective level calculation unit 2c, an average effective level memory 2d, an appearance frequency number distribution diagram calculation unit 2e, a peak position detection unit 2f, and a stationary degree calculation unit 2g. , An input / output characteristic reference unit 2h, an input / output characteristic table 2i, an input / output characteristic function generation unit 2j, and an input / output characteristic function memory 2k. The digital data output from the A / D converter 1b is signal-processed to output the output unit 3. Output to.
[0014]
The frame memory 2b sequentially stores digital data output from the external sound detection unit 1. That is, as shown in FIG. 2, when the storage of the digital data sequence belonging to the first time frame F0 is completed, the digital data sequence of the first time frame F0 is sequentially changed to the digital data sequence belonging to the next time frame F1. Rewrite and repeat this.
[0015]
The average effective level calculation unit 2c calculates the average effective level of the unit time frame from the digital data sequence belonging to the unit time frame when the storage of the digital data sequence belonging to the unit time frame output from the frame memory 2b is completed. .
[0016]
The average effective level memory 2d stores the average effective level p of the unit time frame output by the average effective level calculation unit 2c each time.
[0017]
The appearance frequency number distribution diagram calculation unit 2e creates a frequency distribution diagram indicating the number of time frames (frequency) corresponding to the average effective level p of the time frames sequentially calculated by the average effective level calculation unit 2c.
[0018]
The peak position detection unit 2f detects the mode value of the distribution appearing in the region having a small average effective level in the frequency distribution diagram created by the appearance frequency number distribution diagram calculation unit 2e.
[0019]
The stationarity calculation unit 2g calculates the kurtosis Kw (stationarity) of the frequency distribution within a predetermined range around the mode value detected by the peak position detection unit 2f. Here, the kurtosis Kw represents the sharpness of the distribution.
[0020]
The input / output characteristic reference unit 2h obtains the compression amplification characteristic parameter from the input / output characteristic table 2i in which the stationarity output from the stationarity calculation unit 2g, that is, the kurtosis Kw and the hearing aid fitting data obtained in advance are stored. .
[0021]
In the case of this embodiment, the compression amplification characteristic parameters are the gain g (i) of the linear part, the input level k1 (i), and the input level k2 (i). Here, a case will be described in which the calculated kurtosis Kw is divided into five levels of steadyness. The input / output characteristic table 2i also stores parameters corresponding to the five levels of steadyness.
[0022]
As shown in FIG. 3, the input / output characteristic indicating the relationship between the input sound pressure level and the output sound pressure level is such that the gain is increased for a low input level and is constant up to the input level k1. Linear amplification is performed. The gain is gradually decreased for an input level k1 or higher, and the gain is changed so as not to be amplified for an input level k2 or higher. Here, the input level k1 is called a knee point, and the slope of the characteristic in the portion from the input level k1 to the input level k2 is called a compression ratio.
[0023]
The hearing aid fitting data stored in the input / output characteristic table 2i is obtained as described below, for example. However, in this embodiment, the case where the stationary degree of environmental noise is divided into five stages is considered. Here, the stationarity (1) has a low stationarity (noise whose power fluctuates in a short time, noise in a sheet metal factory, etc.), and the stationarity (5) has a higher stationarity (noise with little fluctuation in power, an air conditioner) Noise).
[0024]
Hearing aid wearer listens most clearly by presenting to each hearing aid wearer a test sound that superimposes the sound of each of these steady-state noises (for example, a speech that reads out a speech sound clarity test term sound or arbitrary text). Input / output characteristic table by obtaining the gain g (i) of the linear part, the input level k1 (i) corresponding to the knee point, and the input level k2 (i) (which the hearing aid wearer feels most comfortable) 2i.
[0025]
There are five types of inspection sounds [1] to [5] shown below.
[1] Noise of normality (1) + speech [2] Noise of normality (2) + speech [3] Noise of normality (3) + speech [4] Noise of normality (4) + speech [5 ] Steadyness level (5) noise + speech sound
The input / output characteristics at each stationary degree are determined by the above method, and the compression amplification characteristic parameters stored in the input / output characteristics table 2i are as shown in FIG. In FIG. 4, the leftmost column is arranged from the top in ascending order of noise continuity. The second column stores the gain g (i) of the linear portion, the third column stores the input level k1 (i) corresponding to the knee point, and the fourth column stores the input level k2 (i).
[0027]
The input / output characteristic function generator 2j outputs the gain g (i) of the linear part, the input level k1 (i) corresponding to the knee point, and the input level at a certain degree of continuity (i) output from the input / output characteristic reference unit 2h. An input / output characteristic function f (k) is generated based on k2 (i), and the input / output characteristic function f (k) is stored in the input / output characteristic function memory 2k.
The input / output characteristic function f (k) generated here takes three forms according to the input level k of sound or noise to the hearing aid .
[0028]
That is, when the input level k is lower than the input level k1 (i) corresponding to the knee point, f (k) = g (i) [dB].
[0029]
When the input level k is higher than the input level k1 (i) corresponding to the knee point and lower than the input level k2 (i), the following equation is obtained.
[0030]
f (k) = g (i) × (k2 (i) −k) / (k2 (i) −k1 (i)) [dB]
[0031]
When the input level k is higher than the input level k2 (i), f (k) = 0 [dB].
[0032]
The input / output characteristic processing unit 2a substitutes the average effective level p of the unit time frame obtained from the average effective level memory 2d for the input / output characteristic function f (k) stored in the input / output characteristic function memory 2k. The gain f (p) of the unit time frame is calculated, multiplied by the digital data Xb in the frame memory 2b, and output to the output unit 3.
[0033]
The output unit 3 includes a D / A converter 3a, an amplifier 3b that amplifies the output signal of the D / A converter 3a with a predetermined gain, and an earphone 3c that performs electroacoustic conversion of the output signal of the amplifier 3b. The digital data signal output from the characteristic processing unit 2a is converted into an analog acoustic signal of a desired level.
[0034]
The operation of the hearing aid device according to the present invention configured as described above will be described with reference to the flowchart shown in FIG.
[0035]
First, in step SP1, the hearing aid device initially sets the average effective level memory 2d, the input / output characteristic function memory 2k, and the frame memory 2b. For example, the input / output characteristic function memory 2k is set with the input / output characteristic function f (k) at the stationary degree (3), and the average effective level memory 2d has a gain of 0 dB at the stationary degree (3). Set k2 (3). All 0 is set in the frame memory 2b.
[0036]
Next, in step SP2, a predetermined total number of time frames (total frequency = Z) necessary for creating the appearance frequency number distribution map is set in the counter (Z), and is necessary for calculating the average effective level p. The number of samples (total number Zf) in a predetermined unit time frame is set in the counter (Zf).
[0037]
Next, in step SP3, the counter (a) for counting the number of time frames for creating the appearance frequency number distribution chart is reset (a = 0).
[0038]
Next, in step SP4, the counter (b) for counting the number of samples in the unit time frame is reset (b = 0).
[0039]
Next, in step SP5, the microphone signal from the microphone 1a is A / D converted at a predetermined sampling frequency by the A / D converter 1b to obtain digital data X′b.
[0040]
In step SP6, the average effective level p stored in the average effective level memory 2d is read.
[0041]
Next, in step SP7, the input / output characteristic function f (k) is read from the input / output characteristic function memory 2k.
[0042]
Next, in step SP8, the gain f (p) is obtained by substituting the average effective level p read from the effective level memory 2d for the input / output characteristic function f (k) read from the input / output characteristic function memory 2k.
[0043]
That is, when the average effective level p is smaller than the input level k1 (3) corresponding to the knee point, f (p) = g (3) [dB].
[0044]
When the average effective level p is larger than the input level k1 (3) corresponding to the knee point and smaller than the input level k2 (3), the following equation is obtained.
[0045]
f (p) = g (3) × (k2 (3) −p) / (k2 (3) −k1 (3)) [dB]
[0046]
When the average effective level p is larger than the input level k2 (3), f (p) = 0 [dB].
[0047]
Next, in step SP9, the input / output characteristic processing unit 2a multiplies the digital data Xb in the frame memory 2b by the gain f (p) to generate an output value R = Xb × f (p).
[0048]
Next, in step SP10, the input / output characteristic processing 2a outputs the generated output value R to the D / A converter 3a of the output unit 3. The output of the D / A converter 3a is amplified by the amplifier 3b, and the output of the amplifier 3b is electroacoustic converted by the earphone 3c and output as an acoustic signal in the ear canal of the hearing aid wearer.
[0049]
In step SP11, the digital data X′b obtained in step SP5 is stored in the frame memory 2b as Xb = X′b.
[0050]
Next, in step SP12, the counter (b) for counting the number of samples within the frame length is incremented (+1).
[0051]
Next, in step SP13, the value of the counter (b) is compared with the value of the counter (Zf) to determine whether or not b ≧ Zf. In the case of b <Zf, since the digital data string per unit time frame has not yet been reached, the process returns to step SP5 to accumulate digital data. On the other hand, when b ≧ Zf, all the digital data strings per unit frame (x ₀ , x ₁ , x ₂ ,..., X _Zf−1 ) are obtained, and the process proceeds to step SP14.
[0052]
In step SP14, the average effective level calculation unit 2c calculates the average effective level p of the unit time frame from the digital data sequence (x ₀ , x ₁ , x ₂ ,..., X _Zf-1 ) belonging to the unit time frame. To do. The average effective level p is calculated by the following equation. In the following equation, n is the number of digital data strings belonging to the unit frame.
[0053]
p = {(x ₀ ² + x ₁ ² + x ₂ ² ... x _Zf-1 ² ) / n} ^1/2
[0054]
Next, proceeding to step SP15, the average effective level p of the unit time frame obtained at step SP14 is stored in the average effective level memory 2d.
[0055]
In step SP16, in order to create a frequency distribution chart in which the horizontal axis has the average effective level p and the vertical axis has the average effective level p, the frequency distribution corresponds to the average effective level p calculated in step SP14. The counter is incremented every time the average effective level p is calculated, and the number of time frames having the average effective level p is counted.
[0056]
Next, in step SP17, the counter (a) is incremented (+1).
[0057]
Next, in step SP18, the value of the counter (a) is compared with a predetermined total frequency Z value to determine whether or not a ≧ Z. In the case of a ≧ Z, since a frequency distribution diagram corresponding to a predetermined total frequency (Z) is obtained, the process proceeds to step SP19. On the other hand, if a <Z, a complete frequency distribution diagram has not been obtained, so the process returns to step SP4, and after setting the counter (b) to b = 0, a predetermined loop is repeated.
[0058]
Frequency distribution diagrams obtained under the condition of a ≧ Z are, for example, as shown in FIGS. Here, FIG. 6 is an example of a frequency distribution diagram when conversational speech is included in noise with a low degree of stationary, and FIG. 7 is a frequency distribution diagram when conversational speech is included in noise with a high degree of stationary. It is an example. In both FIG. 6 and FIG. 7, a distribution A due to environmental noise appears in a region with a low average effective level, and a distribution B due to speech appears in a region with a high average effective level.
[0059]
In general, in a noise, a conversation person talks at a level higher than the noise level in order to avoid the conversation sound being masked by the noise. Therefore, the distribution A caused by the environmental noise is present in a region where the average effective level is low. Appears and a distribution B due to speech appears in a region with a high average effective level.
[0060]
FIG. 8 shows the frequency distribution when the noise distribution and the conversation voice distribution are close to each other and the boundary between the noise distribution and the conversation voice distribution is unclear. Since a part of the distribution of the conversational voice is included on the right side of the noise distribution (the portion of the region where the average effective level is high), it is difficult to calculate the correct steady state. In order to avoid this, in the frequency distribution diagram shown in FIG. 8, the distribution diagram shape of the region of the region where the average effective level is low as viewed from the mode of the noise distribution is folded back toward the high region, and FIG. Step SP19 may be executed after re-creating the symmetrical distribution figure shown.
[0061]
In addition, the distribution A due to noise in FIG. 7 is sharper than the distribution A due to noise in FIG. This is because the noise in FIG. 6 includes various miscellaneous acoustic components as compared with the noise in FIG. 7 as described in the problem to be solved by the invention.
[0062]
Next, in step SP19, the peak position detection unit 2f determines the frequency distribution that appears in the region with the lowest average effective level from the frequency distribution obtained by the appearance frequency distribution map calculation unit 2e, that is, the highest frequency distribution due to noise. The frequent value (LL in FIGS. 6 and 7) is detected.
[0063]
In step SP20, the stationarity calculation unit 2g calculates the kurtosis Kw based on data within a predetermined range centered on the mode of distribution in the range A of FIG. 6 detected by the peak position detection unit 2f. . The kurtosis Kw is defined by the following equation. Where n is the total frequency within a predetermined range, Zi (i = 1, 2,..., N) is the average effective level of each time frame, Zave is the average value of Zi, and V is the variance.
[0064]
Kw = Σ (Zi−Zave) ⁴ / (nV ² ) −3
[0065]
The value of the kurtosis Kw obtained from this equation is used as a scale representing the stationary degree. Further, the greater the value of the kurtosis Kw, the higher the stationarity, and the smaller the value of the kurtosis Kw, the lower the stationarity. The value of the kurtosis Kw is divided into five stages, and the five degrees of stationary degrees from the stationary degree 1 to the stationary degree 5 are obtained.
[0066]
Next, in step SP21, the input / output characteristic reference unit 2h obtains the degree of continuity of the environmental noise output from the stationary degree calculation unit 2g, refers to the input / output characteristic table 2i, and obtains the steady state of the environmental noise obtained here. The compression amplification characteristic parameters corresponding to the degree (the gain g (i) of the linear portion, the input level k1 (i) corresponding to the knee point, and the input level k2 (i)) are obtained from the input / output characteristic table 2i. For example, when the stationary degree of the environmental noise is (5), the gain g (5), the input level k1 (5) corresponding to the knee point, and the input level k2 (5) are obtained.
[0067]
Next, in step SP22, the input / output characteristic function generator 2j sets the compression amplification characteristic parameter (the gain g (5) of the linear part, the input level k1 (5) corresponding to the knee point) currently held by the input / output characteristic reference unit 2h. , The input / output characteristic function f (k) is generated based on the input level k2 (5)).
[0068]
Next, in step SP23, the input / output characteristic function f (k) generated by the input / output characteristic function generator 2j is written into the input / output characteristic function memory 2k.
[0069]
Next, in step SP24, the frequency distribution chart is cleared and the process returns to step SP3. In step SP3, the counter (a) is set to a = 0 as described above.
[0070]
Further, the same processing as described above is executed from step SP4.
[0071]
As described above, in the hearing aid according to the present invention, the test sound obtained by mixing the sound with various noises having different degrees of normality is heard, and the compression amplification characteristic parameter in which the sound included in these test sounds is most easily heard The input / output characteristic table 2i is prepared, and the compression amplification characteristic parameter is called from the input / output characteristic table 2i in accordance with the steady state of the noise in the actual environment. Since the compression amplification characteristic of the input / output characteristic processing unit 2a is set based on the effective level p, it is possible to clearly hear the word sound in various noises having different degrees of normality.
[0072]
In addition, this invention is not limited to the above-mentioned embodiment, Various modified embodiment can be considered.
In the above-described embodiment, the input / output characteristic function is based on the gain g (i) of the linear portion, the input level k1 (i) corresponding to the knee point, and the input level k2 (i) as the compression amplification characteristic parameters. The case where it is configured to generate f (k) has been described.
[0073]
However, since it is only necessary to be able to hear the speech clearly in noise, one of the above three parameters may be selected as a parameter, and other parameters such as attack time and release time may be selected. You may choose. Of course, a combination of these parameters may be selected. In this case, the parameter stored in the input / output characteristic table 2i is the selected parameter.
[0074]
In the embodiment of the present invention, the value of the kurtosis Kw is used as a scale representing the degree of stationarity. However, since the degree of stationarity can be calculated, the standard deviation of the distribution is calculated, and this value may be used as the stationarity. . In this case, as the value of the standard deviation is greater constancy is low, it comes to the higher constancy value of the standard deviation is small.
Further, the most frequent number in the appearance frequency number distribution chart may be set as the stationary degree. In this case, the higher the most frequent number, the higher the stationary degree, and the smaller the most frequent number, the lower the stationary degree.
[0075]
【The invention's effect】
As described above, according to the present invention, it is possible to clearly hear the sound to be listened to regardless of the quality of the environmental noise.
[Brief description of the drawings]
FIG. 1 is a block diagram of a hearing aid according to the present invention. FIG. 2 is an explanatory diagram related to frame division processing. FIG. 3 is an input / output characteristic diagram showing a relationship between an input sound pressure level and an output sound pressure level. FIG. 5 is a flowchart showing the operation of the hearing aid according to the present invention. FIG. 6 is a frequency distribution diagram for explaining the operation of the hearing aid. FIG. 7 is a frequency distribution diagram for explaining the operation of the hearing aid. 8: Frequency distribution diagram for explaining the operation of the hearing aid device [FIG. 9] Frequency distribution diagram for explaining other embodiments [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... External sound detection part, 1a ... Microphone, 1b ... A / D converter, 2 ... Signal processing part, 2a ... Input / output characteristic processing part, 2b ... Frame memory, 2c ... Average effective level calculation part, 2d ... Average effective Level memory, 2e... Appearance frequency distribution diagram calculation unit, 2f... Peak position detection unit, 2g... Steady degree calculation unit, 2h... Input / output characteristic reference unit, 2i. 2k: input / output characteristic function memory, 3: output unit, 3a: D / A converter, 3b: amplifier, 3c: earphone.

Claims (4)

An external sound detecting means for outputting an electric signal corresponding to an external sound, a signal processing means for processing an output signal of the external sound detecting means, and an acoustic output means for converting the output signal of the signal processing means into an acoustic signal In the hearing aid apparatus, the signal processing means detects a steadyness degree of noise included in the external sound from a signal output from the external sound detection means at a predetermined time interval, and an output signal of the external sound detection means Input / output characteristic processing means for compressing and amplifying, and a compression amplification characteristic parameter table storing compression amplification characteristic parameters suitable for a hearing aid wearer, the compression amplification characteristic parameter corresponding to the stationarity output by the stationarity detecting means A hearing aid device that determines input / output characteristics of the input / output characteristics processing means based on The hearing aid according to claim 1, wherein the compression amplification characteristic parameter is a compression ratio. The hearing aid according to claim 1, wherein the compression amplification characteristic parameter is a knee point. The hearing aid according to claim 1, wherein the compression amplification characteristic parameter is a linear gain.

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