Hearing aid

Abstract

To provide a hearing ability auxiliary device capable of suppressing discomfort due to a howl with a simple constitution.SOLUTION: A filter part 15 of a hearing capability auxiliary device 10 preferentially passes a howling component of an audio signal input from a microphone part 11. A detection part 16 detects a level of the howling component. A waveform formation part 17 differentiates a rise part of a detection output voltage that the detection part 16 outputs so as to generate a trigger pulse indicating that a howl is generated. A hold part 18 generates a predetermined-period hold signal on the basis of, the trigger pulse. A muting part 13 is interposed between the microphone part 11 and an earphone part 14, and blocks transmission of the audio signal from the microphone part 11 to the earphone part 14 for a certain time on the basis of the hold signal output from the howl detection part 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hearing aid, and more particularly to a hearing aid capable of suppressing the discomfort caused by howling.

Background Art

[0002] In recent years, digital hearing aids and sound collectors for the hearing-impaired have been increasingly popular, and many models claim to have feedback cancellation.

[0003] Howling is an oscillatory sound generated by a feedback loop that occurs when the microphone sound is amplified and the sound emitted from the earphone speaker is reflected and fed back to the microphone, causing the loop-specific frequency signal to be amplified infinitely until it reaches the dynamic range of the circuit. Howling occurs in hearing aids and sound collectors because when the earphone is brought close to the ear, the sound emitted from the earphone speaker is reflected by the auricle and fed back to the nearby microphone, forming a loop. This is a very annoying sound, and the howling suppression performance is an important factor representing the performance of hearing aids and sound collectors.

[0004] Expensive hearing aids effectively suppress the occurrence of howling. On the other hand, in inexpensive hearing aids and sound collectors, even if they claim to suppress howling, there are many products in which malfunctions occur or the cancellation of howling components is not sufficient, and the howling cancellation performance is not satisfactory.

[0005] Patent Document 1 describes an invention related to a hearing aid that suppresses howling components.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the howling suppression technology related to the background art described above, there is room for improvement from the viewpoint of suppressing the discomfort caused by howling.

[0008] Specifically, the howling suppression technology widely used in digital hearing aids and sound collectors related to the background art described above is a howling cancellation method, which synthesizes signals generated at the same frequency and level as howling in the opposite phase to cancel the generated howling. However, the problem is how accurately a signal for canceling an unstable howling signal can be instantaneously generated. Digital signal processing requires a finite amount of time, and it is quite difficult to adaptively generate an unstable howling signal. Therefore, when the howling component cannot be canceled accordingly, there are problems such as remaining howling or generation of distortion and noise. Furthermore, the characteristic elements for following unstable howling are not simple, and there is difficulty in distinguishing between howling that changes in both level and frequency and speech in the same band.

[0009] The present invention has been made in view of such problems, and an object thereof is to provide a hearing aid that can suppress discomfort caused by howling with a simple configuration.

Means for Solving the Problems

[0011] Moreover, the hearing aid of the present invention is a hearing aid that amplifies and outputs sound collected from the outside, and includes a microphone unit, a howling detection unit, a mute unit, and an earphone unit. The howling detection unit has a filter unit, a detection unit, a waveform shaping unit, and a hold unit. The filter unit preferentially passes the howling component among the voice signals input from the microphone unit. The detection unit detects the level of the howling component. The waveform shaping unit generates a trigger pulse indicating the occurrence of howling by differentiating the rising part of the detection output voltage output by the detection unit. The hold unit generates a hold signal for a predetermined period based on the trigger pulse. The mute unit is interposed between the microphone unit and the earphone unit, and cuts off the transmission of the voice signal from the microphone unit to the earphone unit for a certain period based on the hold signal output from the howling detection unit.

[0012] Moreover, in the hearing aid of the present invention, the filter unit is characterized by attenuating the voice signal in the human voice band.

[0013] Moreover, in the hearing aid of the present invention, the mute unit is characterized by canceling the cut-off after the lapse of the certain time.

Advantages of the Invention

[0015] Furthermore, the hearing aid of the present invention is a hearing aid that amplifies and outputs sound collected from the outside, and includes a microphone unit, a howling detection unit, a mute unit, and an earphone unit. The howling detection unit has a filter unit, a detection unit, a waveform shaping unit, and a hold unit. The filter unit preferentially passes a howling component among the audio signals input from the microphone unit. The detection unit detects the level of the howling component. The waveform shaping unit generates a trigger pulse indicating the occurrence of howling by differentiating the rising part of the detection output voltage output from the detection unit. The hold unit generates a hold signal for a predetermined period based on the trigger pulse. The mute unit is interposed between the microphone unit and the earphone unit, and based on the hold signal output from the howling detection unit, cuts off the transmission of the audio signal from the microphone unit to the earphone unit for a certain period of time. Therefore, according to the hearing aid of the present invention, only when the howling detection unit detects howling, by cutting off the transmission of the audio signal from the microphone unit to the earphone unit for a certain period of time, continuous generation of howling sound during wearing can be suppressed, and the discomfort of the user can be greatly reduced.

[0016] Also, in the hearing aid of the present invention, the filter unit is characterized by attenuating an audio signal in the human voice band. Therefore, according to the hearing aid of the present invention, it is possible to prevent misidentifying human voice as howling sound.

[0017] Also, in the hearing aid of the present invention, the mute unit is characterized by releasing the cut-off after the end of the certain period of time. Therefore, according to the hearing aid of the present invention, the output from the earphone unit can be stopped only during the period when howling occurs, and sound can be output from the earphone unit during the period after the earphone wearing is completed.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

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Figure 7B

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Figure 9

Embodiments for Carrying Out the Invention

[0019] Hereinafter, the hearing aid device 10 according to the embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same members are basically denoted by the same reference numerals, and repeated descriptions are omitted.

[0020] FIG. 1 is a block diagram of the hearing aid device 10.

[0021] The hearing aid 10 is a device that amplifies and outputs sounds collected from the outside, and has a mute unit 13 that stops the output for a certain period of time when howling occurs. Specifically, the hearing aid 10 mainly includes a microphone unit 11, a howling detection unit 12, a mute unit 13, and an earphone unit 14. The hearing aid 10 is, for example, a device that assists the hearing function of elderly people with weakened ear functions, and may also be referred to as a hearing aid or a sound collector, etc.

[0022] Here, the specific connection configuration of the hearing aid 10 will be described. The microphone unit 11, the preamplifier 19, the buffer 20, the mute unit 13, the volume 21, the power amplifier 22, and the earphone unit 14 are connected in series. The input terminal of the howling detection unit 12 is connected to the midpoint between the preamplifier 19 and the buffer 20. The output terminal of the howling detection unit 12 is connected to the mute unit 13. In this embodiment, the loop through which the sound output from the earphone unit 14 is fed back to the microphone unit 11 is referred to as the feedback loop.

[0023] The howling detection unit 12 includes a filter unit 15, a detection unit 16, a waveform shaping unit 17, and a hold unit 18. The filter unit 15, the detection unit 16, the waveform shaping unit 17, and the hold unit 18 are connected in series.

[0024] Here, the functions of each part of the hearing aid 10 will be briefly described.

[0025] The microphone unit 11 generates an audio signal based on the magnitude of the sound input from the outside.

[0026] The preamplifier 19 amplifies the audio signal input from the microphone unit 11.

[0027] The buffer 20 is, for example, an amplifier or a resistor, and has a function of reducing the influence of the output load from feeding back to the input.

[0028] The filter unit 15 preferentially passes the howling component among the audio signals input from the microphone unit 11.

[0029] The detection unit 16 detects the level of the howling component.

[0030] The waveform shaping unit 17 generates a trigger pulse indicating the occurrence of howling by differentiating the rising part of the detected output voltage output by the detection unit 16.

[0031] The hold unit 18 generates a hold signal for a predetermined period based on the trigger pulse.

[0032] The mute unit 13 is interposed between the microphone unit 11 and the earphone unit 14, and blocks the transmission of the audio signal from the microphone unit 11 to the earphone unit 14 for a certain period based on the hold signal output from the howling detection unit 12. Here, the mute unit 13 can be arranged at any position as long as it is between the preamplifier 19 and the earphone unit 14.

[0033] The volume 21 is, for example, a variable resistor, and increases or decreases the output sound according to the user's operation.

[0034] The power amplifier 22 amplifies the input audio signal according to the setting in the volume 21.

[0035] The earphone unit 14 emits a predetermined sound based on the audio signal input from the power amplifier 22.

[0036] To explain the basic functions of the hearing assistance device 10, the sound input to the microphone unit 11 is converted into an audio voltage, power-amplified by the power amplifier 22 via the preamplifier 19, the buffer 20, and the volume 21, and then converted into sound by the earphone unit 14 (earphone) and output as sound pressure.

[0037] On one hand, the howling detection unit 12 extracts a howling signal by the filter unit 15 based on the audio signal input from the preamplifier 19, and the detection unit 16 detects the occurrence of howling by detecting the howling signal. Then, the detection output is held by the hold unit 18 for a certain period of time, and the mute unit 13 is disconnected for a certain period of time by the hold output to eliminate howling. By doing so, it is muted during that period, and no howling audio is output from the earphone unit 14 during the muted period.

[0038] FIG. 2 is a diagram showing the situation where the hearing aid 10 is worn. Here, the wearing part 26 constituting the hearing aid 10 has an earpiece 27, an earphone unit 14, and a microphone unit 11.

[0039] When the user tries to insert the wearing part 26 into the ear canal 28, as described above, a loop is formed in which the sound emitted from the earphone unit 14 and the earpiece 27 is reflected by the auricle 25 and fed back to the nearby microphone unit 11, which may cause howling.

[0040] In the present embodiment, due to the configuration of the hearing aid 10 described above, when howling is detected, a mute that stops the output is executed for a certain period of time. Therefore, when the user tries to wear the hearing aid 10, even if howling occurs, the continuous generation of howling sound can be prevented, and the discomfort caused by howling can be suppressed.

[0041] Referring to the figures after FIG. 3, the functions of each part constituting the hearing aid 10 described above will be described in detail.

[0042] FIG. 3 is a graph showing the function of the filter unit 15 that preferentially passes howling components. In the graph of FIG. 3, the vertical axis represents the magnitude of the audio signal input to the filter unit 15, and the horizontal axis represents the frequency.

[0043] When extracting the howling signal by the hearing aid 10, malfunction may occur in the howling suppression operation due to the influence of voice. Therefore, the voice band is attenuated by the filter unit 15 so that howling and voice can be distinguished. The filter unit 15 is a high-pass filter that hardly attenuates components with frequencies higher than the cutoff frequency of the voice band and attenuates components with frequencies lower than the cutoff frequency. The frequency band of voice is approximately 100 Hz to 2 kHz, and the howling frequency of the hearing aid occurs in the range of 2 kHz to 5 kHz. Therefore, the voice signal in the voice band is attenuated by the filter unit 15. Specifically, the filter unit 15 has a cutoff frequency of 2 kHz and attenuates the voice band from 100 Hz to 500 Hz by about 20 dB. By doing so, the level difference between the howling and the voice signal widens, and a howling signal with less influence of voice can be extracted. Furthermore, malfunction in detecting the howling signal due to voice such as a scream can be prevented. Here, the voice signal before attenuation by the filter unit 15 is shown by a broken line, and the voice signal after attenuation is shown by a dashed line.

[0044] FIG. 4 is a diagram showing the function of the detector unit 16 that detects the level of the howling component. FIG. 4 shows a howling signal, a voice signal, a bias voltage, and a detected output waveform.

[0045] When detecting the howling signal level, the detector unit 16 sets a detection level between the voice level and the howling level in order to eliminate the influence of voice. Specifically, the detector unit 16 is provided with a bias circuit of Vb, blocks signals with a voice signal level of Vb or less, and detects (passes) howling signals with a level of Vb or more.

[0046] FIG. 5 is a diagram showing the functions of the detector unit 16 and the waveform shaping unit 17. FIG. 5 shows a howling signal, the detector unit 16, the waveform after detection, the waveform shaping unit 17, and a trigger pulse.

[0047] The detector unit 16 detects the input howling signal in order to detect the occurrence of howling, and specifically detects the level of the howling component. A detected waveform with the level detected is output from the detector unit 16.

[0048] The waveform shaping section 17 has a capacitor and a resistor. Here, the capacitor is interposed in the connection line connecting the detection section 16, the waveform shaping section 17, and the hold section 18. The resistor is interposed between the connection line and the ground. The waveform shaping section 17 generates a trigger pulse indicating the occurrence of howling by differentiating the rising portion of the detection output voltage output by the detection section 16.

[0049] FIG. 6 is a diagram showing the function of the hold section 18 that generates a hold signal for a predetermined period based on the trigger pulse. In FIG. 6, the trigger pulse, the hold section 18, and the generated pulse are shown.

[0050] The hold section 18 is composed of, for example, a monostable multivibrator circuit. When a trigger pulse is input to the hold section 18, the hold section 18 generates a hold signal which is a pulse for setting the time to cut off the feedback loop. The time T of the hold signal is the time required for the user to insert the wearing portion 26 into the external auditory canal 28, and is, for example, 800 msec. Also, the upper limit value of the time T of the hold signal is preferably 1000 msec, more preferably 900 msec, and particularly preferably 850 msec. On the other hand, the lower limit value of the time T of the hold signal is preferably 600 msec, more preferably 700 msec, and particularly preferably 750 msec. By setting the time T of the hold signal within such a range, the howling sound generated when the user wears the wearing portion 26 can be effectively blocked, and the discomfort caused by the howling sound can be reduced.

[0051] FIG. 7A is a diagram showing the function of the mute section 13. Here, the mute section 13 has a transistor 23. The transistor 23 is disposed between the buffer 20 and the power amplifier 22, and its control electrode is connected to the howling detection section 12.

[0052] Therefore, when the aforementioned hold unit 18 included in the howling detection unit 12 applies a hold signal to the control electrode of the transistor 23, the transistor 23 enters a cut-off state. As a result, the audio signal passing through the preamplifier 19, the capacitor 24, and the buffer 20 does not reach the power amplifier 22. That is, based on the hold signal output from the howling detection unit 12, the transmission of the audio signal from the microphone unit 11 to the earphone unit 14 is blocked for a certain period of time.

[0053] FIG. 7B is a graph showing the function of the mute unit 13, where the horizontal axis represents time and the vertical axis represents the loudness of sound.

[0054] Referring to this graph, the period up to time T1 is the period when the user is trying to insert the wearing unit 26 into the external auditory canal 28. The period from time T1 to time T2 is the period after the insertion of the wearing unit 26 into the external auditory canal 28 is completed. In this embodiment, in particular, by muting the howling that occurs during the period up to time T1, the discomfort caused by the muting to the user is reduced.

[0055] When howling is detected at time T3, the hearing aid 10 cuts off the audio signal transmission with the transistor 23 of the mute unit 13. As a result, the audio signal is not transmitted to the power amplifier 22, and the howling sound does not continuously occur from the earphone unit 14. The transistor 23 continues to block the audio signal transmission for the time from time T3 to time T4, for example, 800 msec. By doing so, the generation of the howling sound from the earphone unit 14 is suppressed, and the discomfort of the user can be suppressed. Note that, before the howling is detected, a slight howling sound is generated from the earphone unit 14, but the period during which the howling sound is generated is very short, for example, about 30 msec, and the sound is like a "pip", so it is considered that the discomfort given to the user is small.

[0056] Thereafter, when time T4 is reached, the mute unit 13 transmits the audio signal. Therefore, for a short period after time T4, the feedback loop is connected, creating an environment in which howling can grow.

[0057] When howling grows again at time T5, the mute unit 13 blocks voice signal transmission again until time T6, stops the generation of howling sound from the earphone unit 14, and suppresses the discomfort of the user.

[0058] That is, in the present embodiment, even if howling occurs multiple times during the period when the user wears the wearing unit 26 on the ear, each time the generation of howling can be stopped and the discomfort of the user can be suppressed by blocking the voice signal transmission.

[0059] FIG. 8 is a graph showing the effect of the hearing aid device 10. In this graph, the horizontal axis represents time, and the vertical axis represents the loudness of the sound output from the earphone unit 14 of the hearing aid device 10.

[0060] As shown in FIG. 2, when the user tries to wear the wearing unit 26 in the external auditory canal 28, howling occurs due to the reverberation of sound by the auricle 25. In the graph of FIG. 8, multiple howlings occur immediately before the insertion of the wearing unit.

[0061] As described above, in the present embodiment, when howling is detected by the howling detection unit 12, the mute unit 13 temporarily blocks the voice output to the earphone unit 14. Therefore, the continuous output of howling sound from the earphone unit 14 is suppressed.

[0062] However, it is also conceivable that the user inserts the wearing unit 26 into the external auditory canal 28 immediately before inserting the wearing unit. In this case, since the sound until the detection of howling audible to the user is as short as several tens of msec as described above, it is a light sound like "pip" and does not matter. Also, if the wearing unit 26 is not worn and howling occurs, howling grows again, and detection and voice muting are repeated, so that the detection sound like "pip, pip" is repeatedly heard. Such a detection sound causes much less discomfort to the user compared to the high-pitched howling sound like "peep".

[0063] After the user wears the wearing part 26, the hearing aid 10 exhibits its original function, amplifies the audio signal input from the microphone part 11, and generates a sound based on the amplified audio signal from the earphone part 14.

[0064] FIG. 9 is a graph showing howling that occurs in a comparative example without the mute function of the present invention. In this graph, the horizontal axis represents time, and the vertical axis represents the magnitude of the sound output from the earphone part 14 of the hearing aid 10.

[0065] In the comparative example, continuous howling sounds are generated immediately before the insertion of the wearing part. Therefore, the user continuously hears the howling sound of "peep peep" generated from the earphone part 14, resulting in a great sense of discomfort. In particular, the howling sound close to the ear canal 28 is irritating and causes a great sense of discomfort to the user.

[0066] On the other hand, in the present embodiment, as described above, by cutting off the howling loop for a certain period of time to stop the howling oscillation, and inserting the wearing part 26 into the ear canal 28 during that time, the wearing part 26 can be worn without hearing unpleasant howling.

[0067] As described above, the embodiments of the present invention have been described. However, the present invention is not limited thereto, and modifications can be made without departing from the gist of the present invention. In addition, the above-described embodiments can be combined with each other.

[0068] This embodiment provides a satisfactory howling suppression technique using a mute method instead of a cancellation method in an inexpensive analog hearing aid or sound collector. Since this embodiment is a fundamental element technology for howling suppression, the howling suppression function can be realized not only by an analog circuit but also by digital signal processing using a DSP.

[0069] Furthermore, in the present embodiment, there are two wearing parts 26 to be worn on the right ear and the left ear, and the hearing aid 10 can be configured individually for each wearing part 26. By doing so, howling sounds generated when inserting the wearing parts 26 into the left and right ears respectively can be suppressed individually.

Explanation of Signs

[0070] 10 Hearing aid 11 Microphone unit 12 Howling detection unit 13 Mute unit 14 Earphone unit 15 Filter unit 16 Detection unit 17 Waveform shaping unit 18 Hold unit 19 Preamplifier 20 Buffer 21 Volume 22 Power amplifier 23 Transistor 24 Capacitor 25 Auricle 26 Wearing part 27 Ear tip 28 External auditory canal

Claims

Claim 1 A hearing aid device that amplifies and outputs sounds collected from the outside, comprising a microphone unit, a howling detection unit, a mute unit, and an earphone unit, wherein the howling detection unit has a filter unit, a detection unit, a waveform shaping unit, and a hold unit, the filter unit preferentially passes howling components among the voice signals input from the microphone unit, the detection unit detects the level of the howling components, the waveform shaping unit generates a trigger pulse indicating the occurrence of howling by differentiating the rising part of the detection output voltage output by the detection unit, the hold unit generates a hold signal for a predetermined period based on the trigger pulse, the mute unit is interposed between the microphone unit and the earphone unit, and blocks the transmission of the voice signal from the microphone unit to the earphone unit for a certain period based on the hold signal output from the howling detection unit. A hearing aid device characterized by this. Claim 2 The hearing aid device according to claim 1, wherein the filter unit attenuates voice signals in the human voice band. Claim 3 The hearing aid device according to claim 1 or claim 2, wherein the mute unit releases the block after the lapse of the certain period.

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