JP3326958B2 - hearing aid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hearing aid, and more particularly to a hearing aid equipped with a feed-forward noise canceller or a feedback noise canceller.

[0002]

2. Description of the Related Art In recent years, various types of hearing aids have been developed. A hearing aid having a unit including an amplifier circuit and a battery and an earphone unit, and an amplifier circuit and a battery housed in the same unit as the earphone unit have been developed. Very small ones that wear on the ear are known.

[0003]

However, no matter what form the hearing aid is, the hearing aid can be clearly heard as long as it is a hearing aid, and the hearing of a normal hearing person who does not use the hearing aid can be improved. It is desirable to be able to hear such a natural feeling. In addition, because it is for the hearing impaired, it is necessary to avoid giving the user an excessive sound pressure burden on the eardrum and causing hearing fatigue to the user.

[0004] However, the sound amplified and output by the hearing aid includes, for example, conversational sound that the user wants to hear, as well as ambient environmental noise. For this reason, even if the volume (hearing aid level) is increased when conversation or the like cannot be heard well, even the noise level is amplified, that is, the audibility is not changed at all in terms of S / N. In addition, increasing the volume causes an excessive sound pressure to be applied to the eardrum, causing a decrease in hearing ability and hearing fatigue. Further, when the volume is increased, howling is likely to occur, and the clarity of the output sound is further reduced.

[0005]

SUMMARY OF THE INVENTION In view of the foregoing problems, an object of the present invention is to provide a hearing aid which cancels out ambient environmental noise and is easy to hear even at a low volume.

For this purpose, the end is inserted into the ear canal and the other end is inserted.
A hearing tube is provided as an opening, and a signal component for a hearing aid that extracts and amplifies a signal component in a predetermined frequency band from a signal supplied from the microphone unit, and performs amplitude and phase compensation processing on the signal supplied from the microphone unit. Amplitude / phase compensating means for adding the output of the hearing aid signal amplifying means and the output of the amplitude / phase compensating means,
The speaker unit that outputs the signal added by the adding means as sound is substantially flush with the inner peripheral surface near the ear of the acoustic tube.
Constitutes a hearing aid provided with hearing aid means provided so as to face the inside of the tube .

[0007] The microphone unit has the end portion.
Near the ear of the acoustic tube with the other end open and inserted into the ear canal
A spike provided so as to face the inside of the pipe while being substantially flush with the inner peripheral surface
May be arranged in the vicinity of the
No.

In this case, a signal is output to the hearing aid signal amplifying means.
Microphone unit and amplitude / phase compensation means
A microphone unit that outputs a signal
The configuration may be such that the crophone unit is also used.

[0009] Two sets of hearing aids having the above-mentioned FF type or FB type noise canceller may be provided corresponding to the left and right ears.

[0010]

By configuring a noise canceller of the FF type or the FB type, the ratio of the sound to be heard to the environmental noise level, that is, the S / N is improved, and a hearing aid which is easy to hear even at a low volume can be realized. Further, if two sets of hearing aids are provided corresponding to the left and right ears, the hearing aid becomes a so-called binaural hearing aid, and more natural listening can be performed.

[0011]

FIG. 1 shows a first embodiment of a hearing aid according to the present invention.
5 to 5, and a second embodiment will be described with reference to FIGS.

FIG. 1 is an external view of a hearing aid of a first embodiment, and 1 indicates the entire hearing aid. Reference numerals 2L and 2R denote a left hearing aid and a right hearing aid attached to the left and right ears, and reference numeral 3 denotes a box in which a battery, a power supply circuit, a hearing aid amplification circuit, and the like are housed. The box 3 includes a power switch 4a for power on / off operation, and volume control knobs 8L and 8 for volume control in the left hearing aid 2L and the right hearing aid 2R.
Operation means such as R are provided. It should be noted that one volume control knob 8 may be provided for both the left and right sides, and the balance may be adjusted by different adjustment units for users with different hearing abilities on the left and right sides.

The tips of the left hearing aid 2L and the right hearing aid 2R are earpieces 5L and 5R, which are inserted into the ear canal when the hearing aid 1 is worn. Reference numerals 6L and 6R denote microphone units, which are attached to positions near the left and right ears, respectively, as shown in the figure. 9
Reference numerals L and 9R denote sound tubes having a long tubular shape, and end portions 9L
₂ , 9R ₂ Is an opening, and a sound absorbing material 1 is provided inside.
0 is filled.

The internal circuits and sound tubes of the box 3, the left hearing aid 2L, and the right hearing aid 2R will be described with reference to FIG.
Since the left hearing aid 2L and the right hearing aid 2R have the same configuration, the left hearing aid 2L will be described, and the right hearing aid 2L will be described.
R is only shown in the figure (each part of the right auditory part 2R is the same as that of the left auditory part 2L, and the same number is "R").
).

The operating power supply voltage V _CC from the power source unit 4 as shown in FIG 2 is supplied to a circuit portion corresponding to the left hearing aid unit 2L and the right hearing aid unit 2R. 11L is a microphone amplifier, which amplifies the signal supplied from the microphone unit 6L. 12L is a hearing aid equalizer, 13L is an amplifier, 14
L is a variable resistance unit. Further, 15L is an amplitude / phase compensation circuit, 16L is an adder, 17L is a drive amplifier, 18L
L is a speaker unit.

The signal amplified by the microphone amplifier 11L is supplied to a hearing aid equalizer 12L and an amplitude / phase compensation circuit 15L. The amplitude / phase compensation circuit 15L performs a compensation process on the input signal so that a sound having the same amplitude and opposite phase as the external sound is output from the speaker unit 18L.

The hearing aid equalizer 12L extracts a signal to be heard by the hearing aid, for example, a signal in a band of about 300 Hz to 3 KHz. That is, an operation like a bandpass filter is performed. It is preferable that the specific equalizing process is variably set in accordance with the user's personal auditory characteristics. In some cases, the amplitude characteristics may be changed using a compressor or the like.

The output of the hearing aid equalizer 12L is the amplifier 1
After being amplified by 3L and level-adjusted by the variable resistor section 14L according to the operation amount of the volume control knob 8L, the adder 1
6L is added to the output of the amplitude / phase compensation circuit 15L. The output of the adder 16L is applied to the speaker unit 18L via the drive amplifier 17L, and is output as sound.

The speaker unit 18L is mounted to face the sound emission surface 18L ₁ to tube side to the acoustic tube 9L as shown. This acoustic tube 9L is the ear canal A
Inner diameter W ₀ and is formed in a tubular body elongated formed substantially the same inner diameter W, earpiece 5L is attached to the end portion 9 L ₁ of the one. Also, the other end 9L ₂
Is the opening of a reflection-free termination of a speech, the sound absorbing material 10 is filled into the tube in between the ends 9 L ₂ from the position near the speaker units 18L.

The earpiece 5L attached to an end portion 9L ₁ of the acoustic tube 9L is formed in the shape shown by the synthetic resin or the like in FIG. 1 for example a flexible ear canal A the tip
To be able to be inserted into the entrance portion C. The inner diameter of the ear piece 5L is the inner diameter W ₀ substantially the same W ₁ of the inner diameter W and the ear canal of the acoustic tube 9 L.

The sound emitting surface 18L _{1 of the} speaker unit 18L
Is designed to face the inside of the acoustic tube 9L substantially flush with the inner peripheral surface thereof, whereby the speaker unit 18L can be mounted without disturbing the acoustic impedance characteristics of the acoustic tube 9L. Become.

When the distal end of the earpiece 5L is inserted into the entrance portion C of the ear canal A and the acoustic tube 9L is mounted, the end 9L _{2 of the} acoustic tube from the eardrum B to the non-reflective end of the acoustic tube. The sound tube 9 </ b> L has a sound path with a constant acoustic impedance because the sound tube 9 </ b> L is continuous with a substantially constant inner diameter.

With this configuration, the speaker unit 18L
Are output from both sides (end 9L ₁₎ in the acoustic tube 9L.
Gradually transmitted it becomes a plane wave to the side and end 9 L ₂ side). Of these, the sound wave that reaches the eardrum B and is reflected again is the acoustic tube 9
Go back to the L side, but since the impedance matching is taken in the acoustic tube 9L, we conducted to the end 9L ₂ side from the end portion 9L ₁ side in the sound tube 9L without reflection elsewhere. And end 9L ₂ Gradually until it reaches the end 9L ₂ Then almost silence. With the acoustic tube 9L and the speaker unit 18L, in this embodiment, the earphone portion is configured as a non-reflection type.

FIG. 5 shows the frequency characteristics of this non-reflective earphone.
Is shown as a solid line. The dashed line indicates the frequency characteristics of the closed earphone used in the conventional hearing aid. In the non-reflective earphone, a flat characteristic is obtained up to a sufficiently low frequency range as shown in FIG.
A manifestation of that leakage of the coupling portion is not the addition of et not be made larger howling margin that there is no leakage. In this case, an acoustic gain of 40 dB or more was obtained, and the magnitude of the howling margin was verified. That is, in the present embodiment, a howling margin is increased by employing a non-reflective earphone, and howling is less likely to occur.

The circuit configuration corresponding to the left hearing aid 2L and the left hearing aid 2L in the box 3 is the right hearing aid 2R.
Are formed in exactly the same way.

The noise canceling operation of the hearing aid 1 will be described. First, FIG. 3 shows the relationship between gain (amplitude compensation) as a noise canceller and eardrum sound pressure. The dotted line is the level of the extraneous sound, the solid line is the amplitude / phase compensation circuit 15L, when the phase of the sound output from the speaker unit 18L is opposite to that of the extraneous sound, and the one-dot chain line is positive for the extraneous sound. A case where a phase output is made from the speaker unit 18L (that is, a case where a noise canceller is not mounted) is shown.

The amplitude / phase compensation circuit 15L performs amplitude compensation on the external sound having the level indicated by the dotted line so that the output of the speaker unit 18L has the amplitude shown as the cancel point in the figure, and further, the phases are reversed. It can be understood that the extraneous sound can be canceled by performing the phase compensation on the second sound. It is also shown that when no noise canceller is installed, howling eventually occurs when the amplitude (amplification gain as a hearing aid) increases.

The compensation characteristic of the amplitude / phase compensation circuit 15L is compensated over a wide band of one decade or more, and can be canceled by an average of about 20 dB in a band of about 50 Hz to 1500 Hz. The output of the amplitude / phase compensation circuit 15L that performs such amplitude and phase compensation is provided to the adder 16L as a feedforward signal.
Hearing aid signal, ie, hearing aid equalizer 12L, amplifier 13
FIG. 4 illustrates how the S / N ratio is improved by adding a signal to the signal via the variable resistor section 14L.

In FIG. 4, it is assumed that the dotted line indicates the level of the extraneous sound, and the dashed line indicates the equalizing characteristics of the hearing aid equalizer 12L. Now, without having a configuration as a noise canceller (amplitude / phase compensation circuit 15L), the output of the hearing aid equalizer 12L is amplified and the speaker unit 18L is amplified.
Output sound from the speaker unit 18L
The characteristics of the eardrum sound pressure, including the extraneous sound directly entering the ear without the aid of a hearing aid together with the output of the sound, are indicated by the bold line. (The bold line indicates the sound equal to the equalizer characteristic and the sound pressure of the external sound level.) Although it is shown as a pressure, the sound pressure is actually set by the amplifier 13L and the variable resistance unit 14L). In the case of this thick line, the relative level of the sound (sound to be heard) with respect to the external noise is, for example, 400 Hz.
Then, the level is indicated by a.

Here, consider the case where the output of the amplitude / phase compensation circuit 15L is added by the adder 16L as in this embodiment. Then, by adding the outputs of the amplitude / phase compensation circuit 15L, as described above, an active cancellation effect of about 20 dB on average is obtained in the band of about 50 to 1500 Hz, and passive sound insulation of external sound based on the shape of the earpiece 5L. With the effect added, 20
An attenuation characteristic of about dB is obtained. This is shown by the broken line in FIG.

At this time, the original hearing aid sound, that is, from the hearing aid equalizer 12L, is added to the adder 16 via the variable resistor 14L.
The characteristic of the audio component supplied to L and output from the speaker unit 18L corresponds to the equalizing characteristic of the dashed-dotted hearing aid equalizer 12L, but the external environmental sound is attenuated from the level indicated by the dotted line to the level indicated by the dotted line. Thus, the relative level of the sound (the sound to be heard) with respect to the external noise is a level indicated by a + b when viewed at 400 Hz. That is, the S / N is greatly improved.

As described above, in the present embodiment, the external environment sound is attenuated over the entire band in advance, and only the signal in the necessary band is amplified, so that the S / N ratio is increased.
And a hearing aid that is very easy to hear can be realized.

Further, since the S / N is largely improved as described with reference to FIG. 4, even if the volume level is lowered to a certain extent, sufficient audibility can be obtained. For example, it is assumed that the volume control knob 8L is operated to change the variable resistor portion 14L, and the volume is reduced, for example, as shown by the thick line in FIG. Here, if it is assumed that a = b, in the case of a thick line, the S / N is about the same as that of the conventional art, that is, the audibility is about the same as that of the conventional art, but the sound pressure load on the eardrum is considerably reduced. .

In other words, when actually used at a volume level between the thick line and 〜, compared with the conventional hearing aid,
The S / N is improved, and the burden on the eardrum can be reduced. Further, howling is effectively prevented by this noise canceling operation.

S / N by the above noise canceling operation
Of the left hearing aid 2L and right hearing aid 2R
Is similarly realized.

Here, the point of obtaining a natural sensation by binaural listening will be considered. Originally, the sound pressure on the eardrum when the head is placed in a sound field having a flat frequency characteristic, that is, the frequency characteristic of the ear itself generally has a rising characteristic of about 10 dB when the sound pressure on the eardrum is 1 kHz or more. This is mainly attributed to the action of the pinna. Therefore, in the case of a hearing aid used near the pinna which causes this phenomenon, it is desirable that the free sound field frequency characteristics be flat.

Regarding this point, it is understood that the adoption of the non-reflection type earphone having the characteristics shown by the solid line in FIG. 5 is suitable for obtaining a natural audibility. In other words, a device used near the pinna is very natural and transmits amplified sound to the ear in an easy-to-listen state.

In the left hearing aid 2L and the right hearing aid 2R, the microphone units 6L and 6R are attached to positions near the left ear and the right ear, so that a binaural effect can be effectively obtained. The auditory sensation of listening to the external sound with the ear can be obtained without the localization being inside the head.

That is, the hearing aid of the present embodiment has a large howling margin as described above, a flat frequency characteristic, a small amount of reflected sound in the external auditory canal, and a mounting position of the microphone unit between the left and right ears. By being close to each other, binaural listening with a natural feeling is realized.
By improving / N, a hearing aid sound that is easier to hear is obtained.

Next, a second embodiment of the present invention will be described. FIG. 6 is an external view of the second embodiment, and FIG. 7 is a configuration diagram. 30
Indicates the entire hearing aid in the form of a headband;
Is a headband to be worn on the head. A housing is attached to the center (top of the head) of the headband 31 to form a power supply unit 4 in which a battery and a power supply circuit are housed. 4a indicates a power switch. A left hearing aid 32L and a right hearing aid 32R are attached to both ends of the headband 31 corresponding to the left and right ears.

Reference numerals 33L and 33R denote storage sections in which amplification circuits, speaker units, and the like are stored, and volume control knobs 8L and 8R are provided in the storage sections 33L and 33R. The operating power supply voltage V _CC is supplied from the power supply unit 4 to the circuits in the storage units 33L and 33R as shown in FIG.

In this case, the left hearing aid 32L and the right hearing aid 32
In the case of R, as can be seen from FIG. 7, the earpieces 5L and 5R are connected to the acoustic tubes 9L and 9L, respectively, as in the first embodiment.
It is attached to the ends 9L ₁ and 9R ₁ of R, and
The speaker units 18L and 18R are sound emitting surfaces 18L ₁ and 1
8R ₁ Is mounted so as to face the inside of the acoustic tube 9L substantially flush with the inner peripheral surface thereof, that is, a non-reflective earphone is formed as in the first embodiment.

Microphone units 6R and 6L are attached to the left hearing aid 32L and the right hearing aid 32R.
R, 6L will be located. Further, the left hearing aid 32
L, the right hearing aid 32R has speaker units 18L, 18L.
Facing the inside of the acoustic tubes 9L and 9R at a position near R
Microphone units 7R and 7L are arranged at positions .

The internal circuits of the left hearing aid 32L and the right hearing aid 32R will be described with reference to FIG. The left hearing aid 32L
The configuration of the right hearing aid unit 32R is identical to the left hearing aid unit 3
Only the 2L will be described, and the right hearing aid 32R will be illustrated only, and the description will be omitted (the same parts are denoted by the same reference numerals with the letter “R” added thereto).

Reference numeral 34L denotes an amplifying and equalizing unit which performs equalizing and amplifying processing as hearing aid sound on the audio signal supplied from the microphone unit 6L, for example, to extract a band of about 300 Hz to 3 KHz. Reference numeral 35L denotes a variable resistance section whose resistance value is adjusted by the volume control knob 8L, 36L denotes a subtractor, 37L denotes a loop filter, 38L denotes a drive amplifier, and 39L denotes a microphone amplifier.

Microphone unit 6 of left hearing aid 32L
In the audio signal obtained in L, a signal in a band desired to be heard is extracted and amplified by an amplification and equalizer section 34L, output level adjusted by a variable resistor section 35L, and then supplied to a subtracter 36L.

The subtractor 36L includes a speaker unit 18
The signal picked up by the microphone unit 7L arranged near the inside of the tube in the vicinity of L is also amplified and supplied by the microphone amplifier 39L. And the subtractor 36L
Then, the signal supplied from the microphone amplifier 39L is subtracted from the signal supplied from the variable resistor unit 13L, and the subtracted output is supplied to the drive amplifier 3L via the loop filter 37L.
The audio signal is supplied from 8L to the speaker unit 18L and output as audio.

That is, the external environmental noise is detected by the microphone unit 7L, and a feedback loop applied as a negative feedback signal to the subtractor 36L is formed. The external sound level is 1 / (loop gain).
Is attenuated. Therefore, in the case of this embodiment as well, the external sound can be attenuated as shown by the broken line in FIG. 4 by the noise canceling action determined by the open loop gain.

Since only the necessary band is amplified by the amplification and equalizer section 34L, the S / N can be remarkably improved as in the case of the first embodiment, and the S / N can be improved. Even if the volume is reduced to some extent by the improvement, the audibility is obtained, and the sound pressure burden on the eardrum can be reduced. Of course, the noise canceling operation is performed in the same manner in the right hearing aid 32R.
These effects are obtained.

Also in this embodiment, the employment of a non-reflection type earphone and the above-described noise canceling operation increase the howling margin and increase the distance between the left and right ears.
It goes without saying that a natural hearing by binaural listening can be obtained by locating the hearing aid of the system and the microphone units 6L and 6R near the left and right ears.

Although the two embodiments have been described above, the present invention is not limited to these, and various modifications are possible. For example, the shape is not limited to the headband type or the box separate type as described above, and may be a two-ear mounting type for left and right.

Although an example in which a non-reflective earphone is employed has been described, the type of the earphone is not limited to this. Furthermore, in the first embodiment, the microphone units 6L and 6R are configured to be used both for collecting the original hearing aid sound and for collecting the external environmental sound. May be provided with a microphone unit.

Further, in the embodiment, the binaural hearing aid can be provided by the two hearing aids of the left and right systems. However, the noise canceller of the present invention can be adopted even if it is a hearing aid of a type which is attached to only one ear.

[0054]

As described above, the hearing aid of the present invention has the following features.
By mounting the circuit means serving as an FF type or FB type noise canceller, it is possible to improve the ratio of the desired sound to the environmental noise level, that is, the S / N, and obtain a clear hearing aid sound. As a result, a hearing aid that is easy to hear even at a low volume can be realized, and the effect of reducing the sound pressure load on the eardrum can be obtained. In addition, a substantial howling margin can be expanded accordingly.

In the case of configuring an FF type noise canceller, one microphone unit serves both as a microphone unit for outputting a signal to the hearing aid signal amplifying means and a microphone unit for outputting a signal to the amplitude / phase compensating means. By doing so, the simplification of the configuration is realized.

If two hearing aids equipped with FF type or FB type noise cancellers are provided corresponding to the left and right ears, a hearing aid capable of binaural listening as well as an improvement in S / N ratio can be obtained, which is more natural. There is an effect that close listening can be performed.

[Brief description of the drawings]

FIG. 1 is an external view of a hearing aid according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a configuration of a hearing aid of the first embodiment.

FIG. 3 is an explanatory diagram of a relationship between a sound pressure on an eardrum and an output gain.

FIG. 4 is an explanatory diagram of a noise canceling operation according to the embodiment.

FIG. 5 is an explanatory diagram of frequency characteristics of the non-reflective earphone of the embodiment.

FIG. 6 is an external view of a hearing aid according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a configuration of a hearing aid of a second embodiment.

[Explanation of symbols]

1,30 Hearing aid 2L, 32L Left hearing aid 2R, 32R Right hearing aid 3 Box 4 Power supply 4a Power switch 5L, 5R Earpiece 6L, 6R, 7L, 7R Microphone unit 8L, 8R Volume control knob 9L, 9R Sound tube 10 Sound absorption Materials 11L, 11R Microphone amplifier 12L, 12R Hearing equalizer 13L, 13R Amplifier 14L, 14R, 35L, 35R Variable resistance unit 15L, 15R Amplitude / phase compensation circuit 16L, 16R Adder 17L, 17R, 38L, 38R Drive amplifier 18L, 18R Speaker unit 31 Headband 34L, 34R Amplification and equalizer unit 36L, 36R Subtractor 37L, 37R Loop filter

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-316588 (JP, A) JP-A-6-22397 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04R 25/00 F01N 1/00 H04R 3/02 H04R 5/027

Claims (4)

(57) [Claims] An end is inserted into an ear canal and the other end is opened.
A hearing aid signal amplification means for extracting and amplifying a signal component in a predetermined frequency band from a signal supplied from the microphone unit, and an amplitude and phase compensation process for the signal supplied from the microphone unit and outputting the signal. Amplitude / phase compensating means, an adding means for adding the output of the hearing aid signal amplifying means and the output of the amplitude / phase compensating means, and a speaker unit for outputting the signal added by the adding means as a sound. Inner circumference and near surface near the ear of the tube
A hearing aid comprising hearing aid means provided so as to face the inside of the tube in one state . 2. The microphone unit according to claim 1 , wherein
Near the ear of the acoustic tube with the other end open with the sound inserted into the ear canal
The switch is provided so that it faces the inside of the pipe while being substantially flush with the inner peripheral surface of the pipe.
It is located near the peaker unit.
The hearing aid according to claim 1, wherein 3. A microphone unit for outputting a signal to the hearing aid signal amplifying unit and a microphone unit for outputting a signal to the amplitude / phase compensating unit, wherein one microphone unit is shared. The hearing aid according to claim 1. 4. The hearing aid according to claim 1, wherein said hearing aid comprises two systems corresponding to the left and right ears.