JP2004032387A - Howling control unit and hearing aid - Google Patents

Howling control unit and hearing aid Download PDF

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Publication number
JP2004032387A
JP2004032387A JP2002186113A JP2002186113A JP2004032387A JP 2004032387 A JP2004032387 A JP 2004032387A JP 2002186113 A JP2002186113 A JP 2002186113A JP 2002186113 A JP2002186113 A JP 2002186113A JP 2004032387 A JP2004032387 A JP 2004032387A
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Prior art keywords
howling
gain
band
audio signal
control
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JP2002186113A
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Japanese (ja)
Inventor
Yasuhiro Terada
寺田 泰宏
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Matsushita Electric Ind Co Ltd
松下電器産業株式会社
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Abstract

An object of the present invention is to provide a howling control device and a hearing aid that can stably suppress howling even when a situation where howling is likely to occur continues.
A howling detecting unit detects a howling of an input acoustic signal, a time measuring unit measures a measuring time during which no howling continues, and a time measuring unit based on a length of the measuring time. Gain upper limit determining section 116 that determines the gain upper limit of the audio signal, gain determiner 117 that determines the gain of the audio signal within a range not exceeding the gain upper limit, and howling that applies a gain to the audio signal and suppresses howling. The suppression unit 118 is provided.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a howling control device and a hearing aid that suppress howling caused by acoustic coupling.
[0002]
[Prior art]
Conventionally, a howling control device determines that a howling has occurred when a sound signal output from a microphone is amplified and a level of the sound signal exceeds a predetermined threshold, and outputs the signal to a sounding body such as a speaker. Howling was suppressed by lowering the level of the acoustic signal.
[0003]
An example of such a conventional howling control apparatus is disclosed in Japanese Patent Application Laid-Open No. 5-207596. This conventional howling control device is applied to a hearing aid.
[0004]
[Problems to be solved by the invention]
However, in such a conventional howling control device, no consideration is given to the case where the howling easily occurs, and the howling suppression is generally released when the level of the acoustic signal becomes smaller than the threshold. Therefore, if a situation where howling is likely to occur continues, there has been a problem that howling, suppression, cancellation of suppression, occurrence, suppression, and cancellation of suppression are repeated. For example, in a hearing aid, if the hearing aid is slightly displaced due to mastication, etc., and howling tends to occur, the occurrence of howling, suppression, cancellation of suppression, occurrence, suppression, cancellation of suppression, which may be annoying to the user, may occur. There was a problem of being repeated.
[0005]
The present invention has been made to solve such a problem, and provides a howling control device and a hearing aid that can stably suppress howling even when a situation where howling is likely to occur continues. Is what you do.
[0006]
[Means for Solving the Problems]
The howling control device of the present invention is a howling detection unit that detects howling for an input sound signal, a time measurement unit that measures a measurement time that is a time during which howling does not continuously occur for the sound signal, A gain upper limit determining unit that determines a gain upper limit of the audio signal based on the length of the measurement time, a gain determiner that determines a gain of the audio signal within a range not exceeding the gain upper limit, and A howling suppression unit that gives the gain to suppress howling.
[0007]
With this configuration, even when a situation where howling is likely to occur continues, the gain upper limit value is determined based on the measurement time during which no howling occurs, and an appropriate value is set so that the gain does not cause howling. Therefore, howling can be suppressed stably.
[0008]
The howling control device according to the present invention includes a band dividing unit that divides the input audio signal into a plurality of frequency bands, and the howling detecting unit has a configuration to detect howling for each of the frequency bands.
[0009]
With this configuration, it is possible to accurately detect howling regardless of the distribution of the level of the level for each frequency band and suppress erroneous howling detection, and thus to stably suppress howling. Can be.
[0010]
The howling control device of the present invention is a band level calculation unit that calculates a plurality of band levels that are levels of the audio signal for each frequency band divided by the band division unit, and an average value of the plurality of band levels. A band level average value calculation unit for calculating a band level average value, wherein the howling detection unit has a configuration for detecting howling based on the magnitude of a ratio between the band level and the band level average value. .
[0011]
According to this configuration, it is possible to accurately detect howling regardless of an increase in the overall level over a plurality of frequency bands and suppress erroneous howling detection, and thus to stably suppress howling. be able to.
[0012]
In the howling control device according to the present invention, the howling detection unit compares a ratio between the band level and the band level average value with a predetermined threshold value for each frame of a fixed length, and the ratio is continuously calculated for a plurality of frames. When the threshold value is exceeded, howling is determined to have occurred.
[0013]
With this configuration, an excessive change in gain is suppressed, and howling can be suppressed more stably.
[0014]
In the howling control device of the present invention, the gain determination unit determines a gain for each frequency band for the audio signal divided into the plurality of frequency bands, and the howling suppression unit performs howling independently for each of the frequency bands. It has a configuration to suppress.
[0015]
With this configuration, howling is suppressed independently for each frequency band, and a sound that is easy to hear can be provided to the user.
[0016]
The howling control device of the present invention has a configuration in which the time measurement unit measures the measurement time for each frequency band, and the gain upper limit value determination unit determines the gain upper limit value for each frequency band. ing.
[0017]
With this configuration, the gain converges to an appropriate value for each frequency band in accordance with the easiness of howling occurring for each frequency band, and thus howling can be suppressed stably.
[0018]
The howling control device of the present invention has a configuration including a band combining unit that combines acoustic signals in which howling is suppressed independently for each frequency band.
[0019]
With this configuration, acoustic signals suppressed independently for each band are synthesized and output.
[0020]
The howling control device of the present invention has a configuration in which the howling suppression unit includes a filter coefficient calculation unit that calculates a coefficient by which the audio signal is multiplied based on the gain, and a parametric equalizer that multiplies the audio signal by the coefficient. are doing.
[0021]
With this configuration, even when a situation where howling is likely to occur continues, the gain upper limit value is determined based on the measurement time during which no howling occurs, and an appropriate value is set so that the gain does not cause howling. Therefore, howling can be suppressed stably.
[0022]
The hearing aid of the present invention includes a microphone that picks up a sound and outputs an audio signal, an amplifier that amplifies the audio signal, the howling control device that performs howling control on the amplified audio signal, and the howling control device. And a receiver that converts the acoustic signal output from the receiver into sound.
[0023]
With this configuration, even when the hearing aid is slightly shifted due to mastication or the like and howling is likely to occur, howling occurs, suppresses, suppresses cancellation, generates, suppresses, etc. The howling can be stably suppressed without the suppression cancellation being repeated.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0025]
(First Embodiment)
FIG. 1 shows a howling control device according to a first embodiment of the present invention. The howling control device 110 in FIG. 1 is applied to a hearing aid.
[0026]
The hearing aid 100 includes a microphone 101 that collects sound, a microphone amplifier 102 that amplifies an analog sound signal output from the microphone 101, and an AD converter that converts the sound signal amplified by the microphone amplifier 102 from analog to digital. 103, an amplifier 104 for amplifying the digital audio signal output from the AD converter 103, a howling control device 110 for performing howling control on the digital audio signal amplified by the amplifier 104, and an output from the howling control device 110. A digital-to-analog converter for converting the converted audio signal from digital to analog, and a receiver for converting the audio signal output from the DA converter 105 to sound.
[0027]
The howling control device 110 includes an input terminal 110a to which an audio signal output from the amplifier 104 is input, a band splitter 111 for splitting the audio signal input to the input terminal 110a into a plurality of frequency bands, and a band splitter 111. A band level calculator 112 that calculates a level (hereinafter, referred to as “band level”) for each frequency band, and an average value of the band levels (hereinafter, referred to as “band level average value”) for the audio signal for each frequency band output from Is calculated by comparing the ratio between each band level and the band level average value (hereinafter referred to as “band level ratio”) with a predetermined threshold value. A howling detection unit 114 that detects how much frequency is detected for each frequency band, and a time during which no howling continues (hereinafter referred to as a “measurement time”). Measuring unit 115 for measuring the frequency for each frequency band, gain upper limit determining unit 116 for determining the gain upper limit of the acoustic signal for each frequency band based on the length of the measurement time, and howling detection result in howling detecting unit 114 , A gain determining unit 117 that determines the gain of the audio signal for each frequency band within a range not exceeding the gain upper limit value, and howling by giving the gain determined by the gain determining unit 117 to the audio signal for each frequency band. , A band synthesizing unit 119 that synthesizes an audio signal for each frequency band output from the howling suppressing unit 118, and an output terminal 110b that outputs the synthesized audio signal.
[0028]
In the present embodiment, howling suppression section 118 gives “gain” to the acoustic signal amplified by amplifier 104. For example, the value of “gain” is set to 1 or less. Note that the value of “gain” may be 1 or more. For example, when the howling suppression unit 118 is configured to also have the function of the amplifier 104 unlike the present embodiment, the “gain” Takes one or more values.
[0029]
Next, the operation of howling control device 110 of the present embodiment will be described. FIG. 2 is a flowchart showing howling control processing in howling control apparatus 110 of the present embodiment.
[0030]
As shown in FIG. 2, first, the band division unit 111 divides the acoustic signal input to the input terminal 110a into a plurality of frequency bands (S201). For example, the audio signal input to the input terminal 110a is buffered for each frame having a frame length of about 10 ms to about 100 ms, and is subjected to means such as a polyphase filter, a fast Fourier transform (FFT), a band pass filter, or the like. A sound signal (hereinafter, referred to as a “band division signal”) divided into a predetermined number of bands M (M is a positive integer) is generated. Subsequent processing is performed for each frame and independently for each frequency band. A band number for identifying a frequency band is hereinafter represented by “i”.
[0031]
Next, the band level calculator 112 sets the band level L for each frequency band. i (T) is calculated (S202). For example, with respect to the band division signal, the power or the amplitude of each frequency band is calculated as a band level. Note that, in order to remove the influence of the minute fluctuation of the level, the calculated band level L i (T) may be smoothed using a past level.
[0032]
Next, the average band level calculating unit 113 calculates the average band level Love (t) (S203). Specifically, M band levels L for each frequency band i By dividing the sum of (t) by the number M of bands, the average band level value Lave (t) is calculated.
[0033]
Next, in the howling detection unit 114, each band level L i By comparing the ratio between (t) and the average band level value Lave (t) (hereinafter referred to as “band level ratio”) with a predetermined threshold value, it is detected whether or not howling has occurred for each frequency band. (S204). FIG. 3 shows an example of such a process in the howling detection unit 114. The processing shown in FIG. 3 is executed for each frequency band.
[0034]
In FIG. 3, first, a howling detection flag dtct_flg indicating whether or not howling has been detected. i And confirms whether or not howling has been detected (S301). Howling detection flag dtct_flg i Is provided for each frequency band, is initially off, and is turned on when howling is detected, as described later. Howling detection flag dtct_flg i Is off, the band level L i (T) and the band level average value Lave (t) based on the band level ratio R i (T) is calculated (S302).
R i (T) = L i (T) / Lave (t) (Equation 1)
Next, the band level ratio R i (T) is compared with a predetermined threshold value TR (S303).
[0035]
Band level ratio R i (T) and the threshold value TR, the band level ratio R i When (t) is larger than the threshold value TR, the counter value dtct_cnt i Is compared with a predetermined number of times n (S304). Counter value dtct_cnt i Are provided for each frequency band, the initial value is “0”, and the band level ratio R i While (t) is larger than the threshold value TR, the value is incremented for each frame. The predetermined number n is equal to the band level ratio R continuously for a predetermined frame. i This is the threshold value of the counter for determining whether (t) has exceeded the threshold value TR. Counter value dtct_cnt i And a predetermined number n, the counter value dtct_cnt i Is larger than the predetermined number n, the average level Lave (t) of the current frame is changed to the reference level Lref. i (S305), and howling detection flag dtct_flg. i Is set to ON (S306). Note that the reference level Lref i Is stored for each frequency band. Counter value dtct_cnt i Is less than the predetermined number n, the counter value dtct_cnt i Is incremented by one (S311).
[0036]
Also, the band level ratio R i And the threshold TR (S303), the result is that the band level ratio R i When (t) is equal to or less than the threshold value TR, the counter value dtct_cnt i Is reset to "0" (S321).
[0037]
Next, in the time measuring unit 115, a measured time how_off_cnt which is a time during which the howling does not continuously occur. i Is measured for each frequency band (S205). Specifically, howling detection flag dtct_flg set by howling detecting section 114 i And howling detection flag dtct_flg i Is set to the measurement time how_off_cnt i Measured as
[0038]
Next, in the gain upper limit determination unit 116, the measurement time how_off_cnt i Gain Gmax of the audio signal based on the length of i Is determined for each frequency band (S206).
[0039]
Gain upper limit Gmax i Is basically determined by measuring time how_off_cnt i Is longer, it is determined that howling is unlikely to occur, and the gain upper limit Gmax is determined. i Is updated so as to approach “1” corresponding to 0 dB, and the measurement time how_off_cnt i Is short, it is determined that howling is likely to occur, and the gain upper limit Gmax is determined. i Is updated to approach, for example, "0.1" corresponding to -20 dB, so that the gain eventually converges to an appropriate value that does not cause howling.
[0040]
For example, the gain upper limit Gmax i Is determined corresponding to each state (first state 401, second state 402, and third state 403) shown in FIG.
[0041]
In FIG. 4, in a first state 401, which is an initial state, the gain upper limit Gmax is calculated according to Equation 2. i To determine.
Gmax i = Gmax i × Gmaxup (Equation 2)
Here, Gmaxup is a gain upper limit value Gmax. i , And takes a value of Gmaxup> 1. For example, the update amount Gmaxup is set to “1.06” corresponding to 0.5 dB. Also, Gmax i Is "1".
[0042]
In the first state 401, the measurement time how_off_cnt i However, when the time is equal to or longer than a predetermined first time, the first state 401 is maintained (411), and when the time is less than the first time, the state moves to the second state 402 (412).
[0043]
In the second state 402, the gain upper limit Gmax i Is maintained without updating.
[0044]
In the second state 402, the measurement time how_off_cnt i Returns to the first state 401 (413) when the measured time exceeds the first time, and the measured time how_off_cnt i When the time is less than a predetermined second time smaller than the first time, the process moves to the third state 403 (414), otherwise, the second state 402 is maintained (415).
[0045]
In the third state 403, the gain upper limit Gmax is calculated according to the following equation (3). i To determine.
Gmax i = Gmax i × Gmaxdn (Equation 3)
Here, Gmaxdn is the gain upper limit Gmax. i , And takes a value of 0 <Gmaxdn <1. For example, the update amount Gmaxdn is set to “0.94” corresponding to −0.5 dB. Also, generally, the gain upper limit Gmax i Is set so as not to lower too much.
[0046]
In the third state 403, the measurement time how_off_cnt i Is longer than the second time, the process returns to the second state 402 (416), otherwise, the third state 403 is maintained (417).
[0047]
Note that the first time and the second time use values in units of frames.
[0048]
Next, the gain determination unit 117 determines the gain of the audio signal for each frequency band (S207). FIG. 5 shows an example of processing in such a gain determination unit 117. The processing shown in FIG. 5 is executed for each frequency band.
[0049]
In FIG. 5, first, howling detection flag dtct_flg i , It is confirmed whether or not howling is detected by the howling detecting unit 114 (S501). Howling detection flag dtct_flg i Is off, the updated gain G updated according to equation 4 i (T) is the gain upper limit Gmax determined by the gain upper limit determiner 116 i Is determined (S502), and the gain upper limit Gmax is determined. i If less, the gain G according to Equation 4 i (T) is updated (S503).
G i (T) = G i (T-1) × Gup1 (Equation 4)
Here, the update amount Gup1 is the gain G i This is an update amount when (t) is increased, and takes a value of Gup1> 1. Gain G after update i (T) is the gain upper limit Gmax i Is determined within a range not exceeding.
[0050]
Howling detection flag dtct_flg i Is on, the gain G is used to release the suppression. i To increase (t) or to suppress howling G i Gain control flag ctrl_gain_flg indicating whether to decrease (t) i Is referred to (S511). Gain control flag ctrl_gain_flg i Is provided for each frequency band, and has a band level L as described later. i It is set to ON when (t) increases and a predetermined condition is satisfied.
[0051]
Gain control flag ctrl_gain_flg i Is off, howling is suppressed according to Equation 5 to suppress howling. i (T) is updated (S512).
G i (T) = G i (T−1) × Gdown (Equation 5)
Here, the update amount Gdown is the gain G i This is the update amount when (t) is lowered, and takes a value of 0 <Gdown <1. Further, by setting the lower limit of the gain, unnecessary suppression is prevented. Next, the band level L i (T) and reference level Lref i (Ie, average band level at the time of howling detection) ratio L i (T) / Lref i Is compared with a predetermined threshold TGC for gain control (S513). As a result of the comparison, the ratio L i (T) / Lref i Is less than the threshold TGC, it is determined that the howling has ceased, and the gain G i The gain control flag ctrl_gain_flg is set so that the step (S521) of returning (t) is performed. i Is set to ON (S514).
[0052]
Also, the gain control flag ctrl_gain_flg i Is on, the gain G according to equation (6) i (T) is updated (S521).
G i (T) = G i (T-1) × Gup2 (Equation 6)
Here, the update amount Gup2 is an update amount when increasing the gain, and takes a value of Gup2> 1. Next, the gain G i It is determined whether (t) has exceeded the gain threshold (S522), and the gain G i When (t) exceeds the gain threshold, howling detection flag dtct_flg i And gain control flag ctrl_gain_flg i Are turned off, and howling detection is restarted (S523). Here, the gain threshold is, for example, a gain upper limit Gmax. i Gain upper limit Gmax 3.0 dB lower than i × 0.7.
[0053]
Next, howling suppressing section 118 multiplies band divided signal Xi (t) divided by band dividing section 111 according to equation 7 by gain Gi (t) determined by gain determining section 117 to obtain howling. Is obtained (S208).
Yi (t) = Xi (t) × Gi (t) (Equation 7)
[0054]
Next, the band synthesizing unit 119 synthesizes an acoustic signal for each frequency band (S209). The sound signal output from the band synthesis unit 119 is input to the DA converter 105 via the output terminal 110b, and the sound with suppressed howling is output from the receiver 106.
[0055]
As described above, in the howling control device according to the present embodiment, a howling detection unit 114 that detects howling, a time measurement unit 115 that measures a measurement time that is a time during which no howling occurs, A gain upper limit determining unit 116 that determines the gain upper limit of the audio signal based on the length of the measurement time; a gain determiner 117 that determines the gain of the audio signal within a range not exceeding the gain upper limit; By providing the howling suppression unit 118 that suppresses howling by giving, even when a situation where howling is likely to occur continues, the gain upper limit value is determined based on the measurement time during which no howling occurs. As a result, the gain converges to an appropriate value that does not cause howling, and thus howling is suppressed stably. It can be.
[0056]
In addition, a band dividing unit 111 that divides the input acoustic signal into a plurality of frequency bands is provided, and the howling detecting unit 114 detects howling for each frequency band. It is possible to accurately detect howling regardless of the distribution state and suppress erroneous howling detection. Therefore, it is possible to stably suppress howling.
[0057]
Also, a band level calculator 112 that calculates a band level that is a level for each frequency band for an audio signal divided into a plurality of frequency bands, and a band level average that calculates an average band level that is an average of the band levels Calculation section 113, and howling detection section 114 detects howling based on the magnitude of the ratio between the band level and the average band level, thereby increasing the overall level over a plurality of frequency bands. Regardless, howling can be accurately detected, and erroneous howling detection can be suppressed. Therefore, howling can be suppressed stably.
[0058]
Also, the gain determination unit 117 determines the gain for each frequency band for the audio signal divided into a plurality of frequency bands, and the howling suppression unit 118 suppresses howling independently for each frequency band. It is possible to provide a user with a sound that is easy to hear.
[0059]
In addition, the time measurement unit 115 measures the measurement time for each frequency band, and the gain upper limit determination unit 116 determines the gain upper limit for each frequency band. The gain converges to an appropriate value for each frequency band in accordance with the ease, so that howling can be suppressed stably.
[0060]
Note that, in the present embodiment, an example has been described in which howling is detected for each frequency band, the time during which no howling occurs is measured, the gain upper limit is determined, the gain is determined, and howling is suppressed. The present invention is not limited to this, and howling is detected according to the overall level of the acoustic signal, not for each frequency band, in accordance with the environment where the howling occurs, the demand for the manufacturing cost, and the like, without departing from the spirit of the present invention. May be configured to measure as one measurement time instead of every frequency band, and may be configured to determine one gain upper limit value instead of each frequency band. It may be configured to determine one gain instead of each band, may be configured to suppress howling collectively instead of each frequency band, It may be configured by appropriately combining those performed for each frequency band.
[0061]
Further, in the present embodiment, an example has been described in which howling is suppressed after amplifying an acoustic signal output from the microphone 101 and converted from analog to digital. However, the present invention is not limited to this, and the howling suppressing unit is not limited to this. It may be configured to also have the function of amplification (the function of the amplifier 104 in FIG. 1).
[0062]
(Second embodiment)
FIG. 6 shows a howling control device according to a second embodiment of the present invention. The howling control device 610 in FIG. 6 is applied to the hearing aid 600. In FIG. 6, the same components as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals and have been described in the first embodiment. .
[0063]
In FIG. 6, howling control device 610 is multiplied by a parametric equalizer 621 for multiplying a sound signal input to input terminal 610 a by a coefficient and a parametric equalizer 621 based on a gain determined by gain determining section 117. A filter coefficient calculator 622 for calculating coefficients.
[0064]
The parametric equalizer 621 shown in FIG. 7 includes a plurality of filters 701 called an IIR (Infinite Impulse Response) filter that performs a filtering process on an audio signal in a time domain, which are connected in series in M stages corresponding to the number of frequency bands. . As shown in FIG. 8, each filter 701 includes a plurality of delay units 811, 812, 813, 814, a plurality of adders 821, 822, 823, and a plurality of multipliers 831, 832, 833, 834, 835. And The filter coefficients calculated by the filter coefficient calculator 622 are set in the multipliers 831, 832, 833, 834, and 835, respectively.
[0065]
The filter coefficient calculation unit 622 performs, for each frequency band, a parametric based on the gain determined by the gain determination unit 117 and a predetermined frequency bandwidth and a value of Q (Quality factor) that determines the characteristics of the filter. The coefficients of the M filters 701 included in the equalizer 621 are calculated.
[0066]
Next, the operation of the howling control device according to the present embodiment will be described. FIG. 9 is a flowchart showing howling control processing in howling control device 610 of the present embodiment.
[0067]
In FIG. 9, the same steps as those in the first embodiment shown in the flowchart of FIG. 2 are denoted by the same reference numerals and have been described in the first embodiment, and thus detailed description will be omitted.
[0068]
The gain upper limit determining unit 116 determines a gain upper limit based on the measured time, which is a time during which no howling continues (S206). Is determined (S207), the filter coefficient calculation unit 622 calculates the filter coefficient (S908). Next, the parametric equalizer 621 multiplies the acoustic signal input from the input terminal 610a by the filter coefficient calculated by the filter coefficient calculator 622 (S909). The acoustic signal output from the parametric equalizer 621 is input to the DA converter 105 via the output terminal 610b, and the howling-controlled sound is output from the receiver 106.
[0069]
As described above, the howling control device according to the present embodiment, like the howling control device according to the first embodiment, generates howling even when a situation where howling is likely to occur continues. The gain upper limit value is determined based on the measurement time that is not present, and the gain converges to an appropriate value that does not cause howling. Therefore, howling can be suppressed stably.
[0070]
【The invention's effect】
Advantageous Effects of Invention According to the present invention, it is possible to provide a howling control device and a hearing aid having an excellent effect that howling can be stably suppressed when howling occurs in a state where howling is likely to occur.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a howling control device according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing howling control processing in the howling control device according to the first embodiment of the present invention;
FIG. 3 is a flowchart illustrating an example of howling detection processing of the howling control device according to the first embodiment of this invention;
FIG. 4 is a state transition diagram for explaining an example of a gain upper limit value determining process of the howling control device according to the first embodiment of the present invention.
FIG. 5 is a flowchart illustrating an example of a gain determination process of the howling control device according to the first embodiment of this invention;
FIG. 6 is a block diagram showing a howling control device according to a second embodiment of the present invention.
FIG. 7 is a diagram showing an example of a parametric equalizer in a howling control device according to a second embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of a filter constituting a parametric equalizer in a howling control device according to a second embodiment of the present invention.
FIG. 9 is a flowchart showing howling control processing in the howling control device according to the second embodiment of the present invention;
[Explanation of symbols]
100, 600 hearing aid
101 microphone
102 microphone amplifier
103 AD converter
104 amplifier
105 DA converter
106 receiver
110,610 Howling control device
111 Band division unit
112 Band level calculator
113 Band Level Average Value Calculation Unit
114 Howling detector
115 Time measurement unit
116 Gain upper limit determination unit
117 Gain determination unit
118 Howling suppression unit
119 Band synthesis unit
621 Parametric equalizer
622 Filter coefficient calculation unit

Claims (9)

  1. A howling detection unit that detects howling for the input sound signal, a time measurement unit that measures a measurement time that is a time during which the howling does not continuously occur for the sound signal, and the time measurement unit that measures the length of the measurement time. A gain upper limit determining unit that determines a gain upper limit of an audio signal, a gain determiner that determines a gain of the audio signal within a range not exceeding the gain upper limit, and suppresses howling by giving the gain to the audio signal. A howling control device comprising:
  2. 2. The howling according to claim 1, further comprising a band division unit that divides the input audio signal into a plurality of frequency bands, wherein the howling detection unit detects howling for each of the frequency bands. 3. Control device.
  3. A band level calculator that calculates a plurality of band levels that are levels of the audio signal for each frequency band divided by the band divider, and a band that calculates an average band level that is an average of the plurality of band levels 3. The apparatus according to claim 2, further comprising a level average value calculation unit, wherein the howling detection unit detects howling based on a magnitude of a ratio between the band level and the band level average value. 4. Howling control device.
  4. The howling detection unit compares a ratio between the band level and the band level average value with a predetermined threshold value for each frame of a fixed length, and when the ratio continuously exceeds the threshold value in a plurality of frames, howling is performed. 4. The howling control device according to claim 3, wherein it is determined that an error has occurred.
  5. The gain determiner determines a gain for each frequency band for the audio signal divided into the plurality of frequency bands, and the howling suppression unit suppresses howling independently for each frequency band. The howling control device according to any one of claims 2 to 4, wherein
  6. The method according to claim 5, wherein the time measurement unit measures the measurement time for each of the frequency bands, and the gain upper limit determination unit determines the gain upper limit for each frequency band. The howling control device according to the above.
  7. The howling control device according to claim 5, further comprising a band synthesis unit that synthesizes an acoustic signal in which howling is suppressed independently for each frequency band.
  8. The method according to claim 1, wherein the howling suppression unit includes a filter coefficient calculation unit that calculates a coefficient by which the audio signal is multiplied based on the gain, and a parametric equalizer that multiplies the audio signal by the coefficient. 5. The howling control device according to any one of 4.
  9. 9. The howling control device according to claim 1, wherein a microphone that picks up a sound and outputs an audio signal, an amplifier that amplifies the audio signal, and howling control on the amplified audio signal. A hearing aid comprising: a receiver that converts an acoustic signal output from the howling control device into a sound.
JP2002186113A 2002-06-26 2002-06-26 Howling control unit and hearing aid Pending JP2004032387A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005081577A1 (en) * 2004-02-20 2005-09-01 Matsushita Electric Industrial Co., Ltd. Howling detection method, device, and acoustic device using the same
WO2006043367A1 (en) * 2004-10-19 2006-04-27 Matsushita Electric Industrial Co., Ltd. Howling suppressor
JP2008199193A (en) * 2007-02-09 2008-08-28 Starkey Japan Co Ltd Hearing aid, and method of manufacturing hearing aid
JP2008199192A (en) * 2007-02-09 2008-08-28 Starkey Japan Co Ltd Hearing aid, and method of manufacturing hearing aid
JP2009508423A (en) * 2005-09-13 2009-02-26 フランス テレコム Spectral characterization for communication equipment
JP2011135485A (en) * 2009-12-25 2011-07-07 Audio Technica Corp Howling suppression apparatus
US8428274B2 (en) 2008-07-01 2013-04-23 Sony Corporation Apparatus and method for detecting acoustic feedback

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005081577A1 (en) * 2004-02-20 2005-09-01 Matsushita Electric Industrial Co., Ltd. Howling detection method, device, and acoustic device using the same
US7796767B2 (en) 2004-02-20 2010-09-14 Panasonic Corporation Howling detection method, device, and acoustic device using the same
WO2006043367A1 (en) * 2004-10-19 2006-04-27 Matsushita Electric Industrial Co., Ltd. Howling suppressor
JP2009508423A (en) * 2005-09-13 2009-02-26 フランス テレコム Spectral characterization for communication equipment
JP2008199193A (en) * 2007-02-09 2008-08-28 Starkey Japan Co Ltd Hearing aid, and method of manufacturing hearing aid
JP2008199192A (en) * 2007-02-09 2008-08-28 Starkey Japan Co Ltd Hearing aid, and method of manufacturing hearing aid
US8428274B2 (en) 2008-07-01 2013-04-23 Sony Corporation Apparatus and method for detecting acoustic feedback
JP2011135485A (en) * 2009-12-25 2011-07-07 Audio Technica Corp Howling suppression apparatus

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