JPS6366120B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an input switching type hearing aid, and more particularly to an input automatic switching type hearing aid that automatically switches between listening to normal sounds and nearby sounds.

(Technical Background of the Invention) Hearing aids are known in which normal conversation and close-range listening, such as over the telephone, are carried out using separate sound collection devices such as microphones or induction coils.

However, in conventional hearing aids of this type, switching was performed by operating a switch.

For this reason, in the case of hearing aids that are required to be significantly miniaturized, if a switch is provided, it will be difficult to operate, and it may be impossible to install a switch.

Furthermore, if the user's switching operation is inappropriate, inconveniences such as difficulty in listening may occur.

(Purpose of the Invention) This invention was made in an attempt to eliminate the drawbacks of the prior art as described above, and provides an automatic input switching type hearing aid that automatically switches between normal sound collection and close sound collection. The purpose is to provide.

(Structure of the invention) In order to achieve this object, according to the invention,
In a hearing aid that is equipped with a microphone for hearing normal sounds and a close-talking microphone for listening to nearby sounds, the close-talking microphone can be used by switching between both or one of these microphones. a filter that extracts a component characteristic of close-in sound from the output signal of the microphone; and a selection circuit that allows the signal from the close-talking microphone to be heard when the output signal of the filter is above a certain level. Make sure to have the following.

(Effects of the Invention) With the above configuration, the present invention can provide an automatic input switching type hearing aid that has the following effects.

(1) Since two types of sound collection devices are automatically switched and used, space for a mechanical switch is not required, and the need for miniaturization is satisfied.

(2) Since no switch is used for switching, there are no problems with operability.

(3) Since the switching is automatic, there are no inconveniences such as difficulty in listening due to inappropriate operation.

(4) It is desirable to keep the microphone active when listening to nearby sounds, as this allows for practical listening.

(5) By using a delay circuit, repeated inappropriate switching can be avoided.

(6) A close-talking microphone is used as the proximity sound collection device, and a filter is connected to extract components specific to the proximity sound, so the state can be determined more accurately and accurate automatic switching can be performed.

(Embodiments of the invention) Examples of the invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of this invention,
This figure shows the configuration of a hearing aid that includes a normal microphone 10 (hereinafter referred to as a normal microphone) and a close-talk microphone 11 (hereinafter referred to as a close-talk microphone).

In addition to these, according to the figure, a bandpass filter 12, a gain adjustment amplifier 13, a level detection circuit 14, a delay circuit 15, switch circuits 16, 17,
A mixer 18, an amplifier 19, and earphones 20 are shown.

The normal microphone 10 is a microphone used to hear normal conversations, and has a fairly high frequency response over substantially the entire audible band.
For example, in a hearing aid using such a microphone, the input sound pressure level is approximately 200 Hz for an input sound pressure level of 60 dB.
It is possible to obtain a flat frequency response of more than 90dB between 600Hz and 600Hz.

The close-talking microphone 11 has air chambers with small holes on both sides of a diaphragm, and is sensitive to the path difference or phase difference of acoustic vibrations that reach the diaphragm through the two small holes. Therefore, when the sound source is close, it exhibits almost the same characteristics as a normal microphone, as shown by curve A in Figure 2, but when the sound source is far away, it exhibits extremely low and mid-range characteristics, as shown by curve B in the same figure. It becomes a characteristic where the component is missing.

The present invention cleverly utilizes the characteristics of such a close-talking microphone.

The bandpass filter 12 therefore detects the middle and low frequency components of the acoustic vibrations of the close-talking microphone 11, and detects whether or not the hearing aid wearer is in a close-talking state. For example, it can be a filter that passes acoustic signals in a band of about 200Hz to 1000Hz.
Further, for example, it may be a low-pass filter that passes signals of 600 Hz or less.

The gain adjustment amplifier 13 is an amplifier whose gain can be adjusted in a semi-fixed manner, and is used to adjust the degree of margin for the next threshold level of the level detection circuit 14.

The level detection circuit 14 has a certain threshold value and sends out a drive signal DS when the output signal of the amplifier 13 exceeds a certain level. Therefore, by adjusting the gain of the amplifier 13 with respect to the threshold level of the level detection circuit 14, the level detection circuit 14 can be operated at a desired input level to the close talk microphone 11.

When there is no output (drive signal DS) from the level detection circuit 14, the delay circuit 15 sends out a signal S0, turns on the switch circuit 17, and normally turns on the microphone 1.
The output signal of 0 is passed through to make it audible.
At this time, the signal S1 is not applied to the switch circuit 16, and the switch circuit 16 is in an off state, and the signal from the close-talking microphone 11 is cut off, so that the close-talking microphone 11 cannot be used for listening. When the drive signal DS is sent out, the delay circuit 15 sends out the signal S1,
Stop sending out the signal S0. For this reason, the switch circuit 16 is turned on, and listening through the close-talking microphone 11 becomes possible, while the switch circuit 17 is turned off, and listening through the microphone 10 becomes impossible.

This delay circuit 15 maintains its output state for a certain period of time even after the output (drive signal DS) of the level detection circuit 14 disappears. Therefore,
Even if the drive signal DS is repeatedly interrupted within a short period of time, the output of the delay circuit 15 can be maintained in the on state. As such a delay circuit 15, various known circuits having a fixed time constant, such as a Schmitt trigger circuit or an integrating circuit, can be used.

The mixer 18 adjusts the level of the signals from each microphone 10, 11, mixes both signals, and sends this mixed signal to the amplifier 19, which is a power amplifier.
and makes it possible to listen to it with the earphones 20. That is, in the above description, the switch circuits 16, 1
It was explained that when one of 7 is operating, the other is not operating. However, usually microphone 1
The switch circuit 17 to which the 0 signal is connected may be always operated, and only the switch circuit 16 to which the signal from the close-talking microphone 11 is connected may be opened or closed.

Next, the operation of this embodiment will be explained.

First, in normal conditions, such as indoor conversation or general listening on the street, the close-talking microphone 11 detects almost no mid-low frequency components because the sound source is far away. Therefore, since this band component is hardly input to the bandpass filter 12, the output signal DS of the level detection circuit 14 is logic "0" (DS=0). Therefore, the delay circuit 15 sends out the output signal S0 to the switch circuit 17.
When the hearing aid is turned on, the hearing aid wearer can normally hear through the microphone 10.

Second, when a hearing aid wearer listens to nearby sounds such as a telephone, the close-talking microphone 11 detects mid-low frequency components as described above. Therefore, the bandpass filter 12 outputs only the middle and low frequency components. When this level is above a certain value, the output signal DS of the level detection circuit 14 becomes 1. Therefore, the delay circuit 15 sends out the output signal S1, turns on the switch circuit 16, and listening with the close-talking microphone becomes possible.

As can be seen from the above, by selecting the gain of the gain adjustment amplifier 13 and the threshold of the level detection circuit 14, it is possible to determine the degree of proximity or proximity sound that can be heard by the close-talking microphone 11. I can do it.

This invention is not limited to the above embodiments, but includes various modifications within the same technical idea.

In addition, the "selection circuit" in the "claims" refers to
It includes a gain adjustment amplifier 13, a level detection circuit 14, a delay circuit 15, and switch circuits 16 and 17 as appropriate.

[Brief explanation of drawings]

FIG. 1 is a system diagram according to an embodiment of the present invention, and FIG.
The figure is an explanatory diagram of the operation of the main part of the embodiment of FIG. 1. 10... Normal microphone, 11... Close-talking microphone (proximity sound collection device), 12... Filter, 13... Gain adjustment amplifier, 14... Level detection circuit, 15...
...Delay circuit, 16, 17...Switch circuit, 18
...Mixer, 19...Amplifier, 20...Earphone.

Claims (1)

[Scope of Claims] 1. A microphone for listening to normal sounds and a close-talking microphone for listening to nearby sounds. Both or one of these microphones can be used by switching. The hearing aid includes a filter that extracts components specific to nearby sounds from the output signal of the close-talking microphone, and a filter that allows the signal from the close-talking microphone to be heard when the output signal of the filter is above a certain level. What is claimed is: 1. An automatic input switching type hearing aid, characterized in that it is equipped with a selection circuit that makes it possible to switch inputs. 2. In the hearing aid according to claim 1, the selection circuit includes a delay circuit that sends out an output for a predetermined time even after the output signal level of the filter falls below a certain value, and the output of the delay circuit An automatic input switching type hearing aid, characterized in that a switch circuit in the selection circuit is driven by a switch circuit in the selection circuit. 3. The hearing aid according to claims 1 and 2, characterized in that the selection circuit includes a first switch circuit for passing or blocking the signal from the close-talking microphone. Hearing aids with automatic input switching. 4. An automatic input switching type hearing aid according to any one of claims 1 to 3, characterized in that the normal sound is always heard. 5. In the hearing aid according to any one of claims 1 to 4, the selection circuit includes a second selection circuit for passing or blocking the output signal of the microphone for listening to the normal sound. 1. An automatic input switching type hearing aid comprising a switch circuit, which is operated by switching with the first switch circuit.