Hearing aids

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 assistance device, and particularly to a hearing assistance device capable of suppressing discomfort caused by howling. [[Background Art]]

[0002] In recent years, digital products have become increasingly popular among hearing aids and sound collectors for hearing-impaired people, and an increasing number of models advertise howling cancellation functionality.

[0003] Howling is an oscillation sound generated when a feedback loop is formed after microphone sound is amplified, and sound emitted from an earphone speaker is reflected and fed back to the microphone. In this process, a frequency signal specific to the loop is repeatedly amplified infinitely, and amplified to the dynamic range of the circuit. Howling occurs in hearing aids and sound collectors because when an earphone is brought close to the ear, sound emitted from the earphone speaker is reflected by the auricle, forming a loop that feeds back to the adjacent microphone. This is a very jarring sound, and howling suppression performance is an important factor representing the performance of hearing aids and sound collectors.

[0004] Expensive hearing aids reliably suppress the occurrence of howling. On the other hand, among low-cost hearing aids and sound collectors, even for models that advertise howling suppression, many products do not provide satisfactory howling cancellation performance: malfunctions may occur, or howling components may not be sufficiently canceled.

[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]] Japanese Unexamined Patent Publication No. 2015-57873 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0007] However, the feedback suppression technology related to the background technology mentioned above had room for improvement in terms of suppressing the discomfort caused by feedback.

[0008] Specifically, the feedback suppression technology widely used in digital hearing aids and sound amplifiers, as mentioned above, is a feedback cancellation method. This technology cancels the generated feedback by synthesizing a signal generated at the same frequency and level as the feedback in inverse phase. However, the challenge lies in how accurately and instantaneously a signal that cancels the unstable feedback signal can be generated. Digital signal processing requires a finite amount of time, and adaptively generating an unstable feedback signal is quite difficult. Therefore, if the feedback component cannot be tracked and canceled, problems such as residual feedback, distortion, or noise occur. Furthermore, the characteristic elements required to track unstable feedback are not simple, and there is difficulty in distinguishing between feedback, which changes in both level and frequency, and sound in the same frequency band.

[0009] This invention was made in view of these problems, and aims to provide a hearing aid that can suppress discomfort caused by howling with a simple configuration. [Means for solving the problem]

[0010] The present invention is a hearing assistance device that amplifies and outputs sound collected from an external source, comprising: a hold unit that generates a hold signal for a predetermined period of time; and a mute unit that, when howling occurs, stops the output based on the hold signal to interrupt the transmission of the audio signal from the microphone unit to the earphone unit for a certain period of time, wherein the hold unit includes a monostable multicircuit. The monostable multicircuit is a circuit that, when a trigger pulse is input, outputs the hold signal for a predetermined time, and stops outputting after the predetermined time has elapsed, wherein the predetermined time is 600 msec or more and 1000 msec or less. It is characterized by the following: [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a hearing aid that can suppress discomfort caused by howling with a simple configuration. [Brief explanation of the drawing]

[0012] [Figure 1] This is a block diagram of a hearing assistance device according to an embodiment of the present invention. [Figure 2] This figure shows the situation in which the hearing assistance device according to an embodiment of the present invention is worn. [Figure 3] This is a graph showing the function of the filter section in a hearing assistance device according to an embodiment of the present invention. [Figure 4] This figure shows the function of the detection unit in a hearing assistance device according to an embodiment of the present invention. [Figure 5] This diagram shows the functions of the detection unit and the waveform shaping unit in a hearing assistance device according to an embodiment of the present invention. [Figure 6] This figure shows the function of the holding part in a hearing assistance device according to an embodiment of the present invention. [Figure 7A] This figure shows the function of the mute unit in a hearing assistance device according to an embodiment of the present invention. [Figure 7B] This graph shows the effect of the mute section in a hearing assistance device according to an embodiment of the present invention. [Figure 8] This graph shows the effects of the hearing assistance device according to an embodiment of the present invention. [Figure 9] This graph shows the feedback that occurs in the comparative example. [Modes for carrying out the invention]

[0013] Hereinafter, a hearing assistance device 10 according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals will be used for the same components in principle, and repeated descriptions will be omitted.

[0014] Figure 1 is a block diagram of the hearing assistance device 10.

[0015] The hearing assistance device 10 is a device that amplifies and outputs sound collected from the outside, and includes a mute unit 13 that stops output for a fixed period of time when howling occurs. Specifically, the hearing assistance device 10 mainly includes a microphone unit 11, a howling detection unit 12, a mute unit 13, and an earphone unit 14. The hearing assistance device 10, for example, assists the hearing function of elderly people with weakened ear function, and may also be referred to as, for example, a hearing aid or a sound collector.

[0016] Here, a specific connection configuration of the hearing assistance device 10 will be described. The microphone unit 11, a preamplifier 19, a buffer 20, the mute unit 13, a volume 21, a power amplifier 22, and the earphone unit 14 are connected in series. An input terminal of the howling detection unit 12 is connected to an intermediate point between the preamplifier 19 and the buffer 20. An output terminal of the howling detection unit 12 is connected to the mute unit 13. In the present embodiment, a loop in which sound output from the earphone unit 14 is fed back to the microphone unit 11 is referred to as a feedback loop.

[0017] 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.

[0018] Here, the functions of each part of the hearing assistance device 10 will be briefly described.

[0019] The microphone unit 11 generates an audio signal based on the volume of sound input from the outside.

[0020] The preamplifier 19 amplifies the audio signal input from the microphone unit 11.

[0021] The buffer 20 is, for example, an amplifier or a resistor, and has a function of reducing feedback of the influence of an output load to an input side.

[0022] The filter unit 15 preferentially passes howling components in the audio signal input from the microphone unit 11.

[0023] The detection unit 16 detects the level of the howling component.

[0024] The waveform shaping unit 17 generates a trigger pulse indicating the occurrence of howling by differentiating the rising edge of the detected output voltage outputted by the detection unit 16.

[0025] The hold unit 18 generates a hold signal for a predetermined period of time based on the trigger pulse.

[0026] The mute unit 13 is interposed between the microphone unit 11 and the earphone unit 14, and based on the hold signal output from the howling detection unit 12, it blocks the transmission of audio signals from the microphone unit 11 to the earphone unit 14 for a certain period of time. Here, the mute unit 13 can be placed at any location between the preamplifier 19 and the earphone unit 14.

[0027] Volume 21 is, for example, a variable resistor that adjusts the output sound according to user input.

[0028] The power amplifier 22 amplifies the input audio signal according to the setting on the volume control 21.

[0029] The earphone unit 14 emits a predetermined sound based on the audio signal input from the power amplifier 22.

[0030] To explain the basic function of the hearing assistance device 10, the sound input to the microphone unit 11 is converted into an audio voltage, which is then amplified by the power amplifier 22 via the preamplifier 19, buffer 20, and volume control 21, and finally converted back into sound by the earphone unit 14 (earphone) and output as sound pressure.

[0031] Meanwhile, the howling detection unit 12 extracts the howling signal in the filter unit 15 based on the audio signal input from the preamplifier 19, and the detection unit 16 detects the howling signal to detect the occurrence of howling. The detection output is then held for a certain period of time in the hold unit 18, and the howling is eliminated by using the hold output to disconnect the mute unit 13 for a certain period of time. In this way, the system is muted during that time, and no howling sound is output from the earphone unit 14 during the muted period.

[0032] Figure 2 shows the situation in which the hearing aid device 10 is worn. Here, the wearing part 26 that constitutes the hearing aid device 10 has an earpiece 27, an earphone part 14, and a microphone part 11.

[0033] When a user attempts to insert the earpiece 26 into the ear canal 28, as described above, the sound emitted from the earphone 14 and earpiece 27 reflects off the auricle 25 and returns to the nearby microphone 11, creating a loop that may cause feedback.

[0034] In this embodiment, the configuration of the hearing aid device 10 described above enables a mute function to be activated when feedback is detected, which stops the output for a certain period of time. Therefore, even if feedback occurs when a user attempts to put on the hearing aid device 10, it is possible to prevent continuous feedback noise and suppress discomfort caused by feedback.

[0035] Referring to Figures 3 and onward, the functions of each component of the aforementioned hearing assistance device 10 will be explained in detail.

[0036] Figure 3 is a graph showing the function of the filter section 15, which preferentially passes through howling components. In the graph in Figure 3, the vertical axis represents the magnitude of the audio signal input to the filter section 15, and the horizontal axis represents the frequency.

[0037] When the hearing aid 10 extracts the howling signal, the howling suppression operation may malfunction due to the influence of sound. Therefore, the filter unit 15 attenuates the sound band so that howling and sound can be distinguished. The filter unit 15 is a high-pass filter that hardly attenuates components at frequencies higher than the cutoff frequency of the sound band, while gradually reducing components at frequencies lower than the cutoff frequency. The frequency band of sound is approximately 100Hz to 2kHz, and the howling frequency of hearing aids occurs in the range of 2kHz to 5kHz. Therefore, the sound signal in the sound band is attenuated by the filter unit 15. Specifically, the filter unit 15 has a cutoff frequency of 2kHz and attenuates the sound band from 100Hz to 500Hz by about 20dB. In this way, the level difference between the howling and the sound signal widens, and a howling signal with less influence from sound can be extracted. Furthermore, it is possible to prevent malfunctions in howling signal detection caused by sounds such as shouting. Here, the audio signal before attenuation by the filter section 15 is shown with a dashed line, and the audio signal after attenuation is shown with a dotted line.

[0038] Figure 4 shows the function of the detection unit 16 that detects the level of the howling component. Figure 4 shows the howling signal, audio signal, bias voltage, and detection output waveform.

[0039] The detection unit 16 sets a detection level between the audio level and the howling level to eliminate the influence of audio when detecting the howling signal level. Specifically, the detection unit 16 provides a Vb bias circuit to block audio signals below Vb and detect (pass through) howling signals above Vb.

[0040] Figure 5 shows the functions of the detection unit 16 and the waveform shaping unit 17. In Figure 5, the howling signal, the detection unit 16, the waveform after detection, the waveform shaping unit 17, and the trigger pulse are illustrated.

[0041] The detection unit 16 detects the input howling signal to detect the occurrence of howling, specifically by detecting the level of the howling component. The detection unit 16 outputs the detected waveform.

[0042] The waveform shaping unit 17 includes a capacitor and a resistor. Here, the capacitor is interposed in the connecting wire that connects the detection unit 16, the waveform shaping unit 17, and the hold unit 18. The resistor is interposed between the connecting wire and ground. The waveform shaping unit 17 generates a trigger pulse indicating the occurrence of howling by differentiating the rising edge of the detected output voltage output output by the detection unit 16.

[0043] Figure 6 shows the function of the hold unit 18, which generates a hold signal for a predetermined period based on a trigger pulse. Figure 6 shows the trigger pulse, the hold unit 18, and the generated pulse.

[0044] The hold unit 18 consists of, for example, a monostable multicircuit. When a trigger pulse is input to the hold unit 18, the hold unit 18 generates a hold signal, which is a pulse for setting the time to disconnect the feedback loop. The hold signal time T is the time required for the user to insert the attachment unit 26 into the ear canal 28, for example, 800 msec. The upper limit of the hold signal time T is preferably 1000 msec, more preferably 900 msec, and particularly preferably 850 msec. On the other hand, the lower limit of the hold signal time T is preferably 600 msec, more preferably 700 msec, and particularly preferably 750 msec. By setting the hold signal time T within this range, howling noise generated when the user attaches the attachment unit 26 can be effectively blocked, and discomfort caused by howling noise can be reduced.

[0045] Figure 7A shows the function of the mute unit 13. Here, the mute unit 13 has a transistor 23. The transistor 23 is located between the buffer 20 and the power amplifier 22, and its control electrode is connected to the howling detection unit 12.

[0046] 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 is disconnected. Consequently, the audio signal that has passed through the preamplifier 19, capacitor 24, and buffer 20 does not reach the power amplifier 22. In other words, 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.

[0047] Figure 7B is a graph showing the function of the mute unit 13, with the horizontal axis representing time and the vertical axis representing the volume of sound.

[0048] Referring to this graph, the period up to time T1 is the time when the user is attempting to insert the attachment part 26 into the ear canal 28. The period from time T1 to time T2 is the time after the insertion of the attachment part 26 into the ear canal 28 is completed. In this embodiment, in particular, the discomfort caused to the user by muting the howling that occurs during the period up to time T1 is reduced.

[0049] If feedback is detected at time T3, the hearing aid 10 blocks the transmission of the audio signal using the transistor 23 of the mute unit 13. As a result, the audio signal is not transmitted to the power amplifier 22, and feedback sounds are not continuously generated from the earphone unit 14. The transistor 23 continues to block the transmission of the audio signal for a period of time from time T3 to time T4, for example, 800 msec. In this way, feedback sounds are suppressed from being emitted from the earphone unit 14, and user discomfort can be reduced. Although some feedback sounds may be generated from the earphone unit 14 before feedback is detected, the duration of the feedback sound is very short, for example, about 30 msec, and may only be a slight "beep" sound, so the discomfort to the user is considered to be minimal.

[0050] Subsequently, the mute unit 13 transmits the audio signal when time T4 is reached. Therefore, for a period of time after time T4, the feedback loop is connected, creating an environment where howling can grow.

[0051] If feedback intensifies again at time T5, the mute unit 13 will again block audio signal transmission until time T6, stopping the feedback sound from being emitted from the earphone unit 14 and suppressing user discomfort.

[0052] In other words, in this embodiment, even if feedback occurs multiple times during the period when the user wears the attachment part 26 on their ear, the transmission of the audio signal is interrupted each time, thereby stopping the feedback and suppressing discomfort for the user.

[0053] Figure 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.

[0054] As shown in Figure 2, when the user attempts to insert the attachment part 26 into the ear canal 28, feedback occurs due to sound reflection by the auricle 25. In the graph in Figure 8, multiple instances of feedback occur immediately before insertion of the attachment part.

[0055] As described above, in this embodiment, when the howling detection unit 12 detects howling, the mute unit 13 temporarily blocks the audio output to the earphone unit 14. Therefore, the continuous output of howling sound from the earphone unit 14 is suppressed.

[0056] However, it is also possible that the user may insert the attachment part 26 into the ear canal 28 immediately before insertion. In this case, the sound heard by the user until the feedback is detected is, as mentioned above, only a short time of several tens of milliseconds, so it is a light "beep" sound and does not bother the user. Also, if feedback occurs when the attachment part 26 is not attached, the feedback will grow again, and detection and audio muting will be repeated, so the "beep, beep" detection sound will be heard repeatedly. Compared to the high-pitched "beep beep" sound of feedback, this detection sound causes far less discomfort to the user.

[0057] Furthermore, after the user puts on the wearable part 26, the hearing assistance device 10 performs its intended function, amplifying the audio signal input from the microphone part 11, and sound based on the amplified audio signal is generated from the earphone part 14.

[0058] Figure 9 is a graph showing howling that occurs in a comparative example of the present invention that does not have a mute function. In this graph, the horizontal axis represents time, and the vertical axis represents the loudness of the sound output from the earphone section 14 of the hearing aid 10.

[0059] In the comparative example, a continuous howling sound is generated immediately before insertion into the earpiece. As a result, the user experiences significant discomfort from continuously hearing the "beep-beep" howling sound emanating from the earphone unit 14. Howling sounds, especially those close to the ear canal 28, are irritating and cause considerable discomfort to the user.

[0060] On the other hand, in this embodiment, as described above, howling oscillation is stopped by disconnecting the howling loop for a certain period of time, and the attachment part 26 is inserted into the ear canal 28 during that time, so the attachment part 26 can be attached without hearing unpleasant howling.

[0061] Although embodiments of the present invention have been described above, the present invention is not limited thereto, and modifications are possible without departing from the spirit of the invention. Furthermore, the above-described embodiments can be combined with each other.

[0062] This embodiment provides a satisfactory feedback suppression technology for inexpensive analog hearing aids and sound amplifiers, using a muting method rather than a cancellation method. Since this embodiment is a fundamental element of feedback suppression technology, the feedback suppression function can be realized not only with analog circuits but also with digital signal processing using a DSP.

[0063] Furthermore, although this embodiment has two attachment parts 26 that are attached to the right and left ears, the hearing assistance device 10 can be configured individually in each attachment part 26. In this way, howling sounds that occur when inserting the attachment part 26 into each ear can be suppressed individually.

[0064] The inventions that can be understood from the embodiments described above, along with their effects, are described below.

[0065] The hearing assistance device of the present invention is a hearing assistance device that amplifies and outputs sound collected from an external source, and is characterized by having a mute unit that stops the output for a certain period of time when feedback occurs. Therefore, according to the hearing assistance device of the present invention, when feedback is detected, the mute is executed to stop the output for a certain period of time, so even if feedback occurs when the user wears the hearing assistance device on their ear, the feedback sound will not be continuously generated, and thus the discomfort caused by feedback can be suppressed.

[0066] Furthermore, the hearing assistance device of the present invention is a hearing assistance device that amplifies and outputs sound collected from the outside, and comprises 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, wherein the filter unit preferentially passes the howling component of the audio signal input from the microphone unit, the detection unit detects the howling component at a level, the waveform shaping unit generates a trigger pulse indicating the occurrence of howling by differentiating the rising edge of the detected output voltage output output by the detection unit, the hold unit generates a hold signal for a predetermined period based on the trigger pulse, and 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, blocks 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 assistance device of the present invention, when howling is detected by the howling detection unit, the transmission of the audio signal from the microphone unit to the earphone unit is blocked for a certain period of time, thereby suppressing the continuous generation of howling sounds during wear and significantly reducing user discomfort.

[0067] Furthermore, the hearing assistance device of the present invention is characterized in that the filter unit attenuates the audio signal in the human voice frequency band. Therefore, the hearing assistance device of the present invention can suppress the misidentification of human voice as feedback sound.

[0068] Furthermore, in the hearing assistance device of the present invention, the mute unit releases the mute after the specified period of time has elapsed. Therefore, according to the hearing assistance device of the present invention, the output from the earphone unit is stopped only during the period when feedback is occurring, and sound can be output from the earphone unit during the period after the earphone is no longer worn. [Explanation of Symbols]

[0069] 10 Hearing aids 11 Microphone section 12 Howling detection unit 13. Mute section 14. Earphone section 15 Filter section 16 Detection section 17 Waveform shaping section 18. Holding section 19 Preamplifier 20 buffers 21 Volume 22 Power Amplifiers 23 Transistors 24 Capacitors 25 Auricle 26 Mounting part 27 Eartips 28 Ear canal

Claims

[Claim 1] It is a hearing assistance device that amplifies and outputs sounds collected from the outside. A hold unit that generates a hold signal for a predetermined period, The device comprises a mute unit that, when howling occurs, stops the output that blocks the transmission of audio signals from the microphone unit to the earphone unit for a certain period of time based on the hold signal, The holding section includes a monostable multicircuit, The monostable multicircuit is a circuit that, when a trigger pulse is input, outputs the hold signal for a predetermined time, and stops outputting after the predetermined time has elapsed, wherein the predetermined time is 600 msec or more and 1000 msec or less, and is characterized as a hearing aid device.

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