JPH08280099A - Hearing aid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hearing aid capable of considering the impedance of the auditory organ of a user not uniform due to an individual difference or a disease over a transmitted frequency range. SOLUTION: A microphone 1 is connected to the serial connection of an amplifier 2, a signal processing circuit 3 constituted of a voltage controlled amplifier and a voltage controlled filter, etc., and an output transducer. The output transducer is formed by a coil 5 for generating an alternating magnetic field and cooperating with a permanent magnet 6 transplanted or attached in the ear 30 such as the ear drum or between the ear drum and a malleus or the like. Further, a reference microphone 7 is arranged in front of the ear drum and connected to the signal processing circuit 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a microphone arranged in a case, the microphone comprising at least one amplifier, a signal processing circuit such as a voltage controlled amplifier and / or a voltage controlled filter, and an output transducer. Connected in series with and the output transducer is formed by a coil that produces an alternating magnetic field and cooperates with a permanent magnet that is implanted or attached to the eardrum or to the ear, such as between the eardrum and the stalk between the malleus, A hearing aid with an output transducer that produces an alternating magnetic field and cooperates with a permanent magnet that is either attached to the ear or implanted.

[0002]

BACKGROUND OF THE INVENTION Two types of hearing aids are known for assisting people, especially those with impaired hearing. The most commonly used type is without doubt airborne sound hearing aids. In this system, ambient sound (voice, music, etc.) is received by a microphone, its output signal is electronically amplified, and the amplified signal is converted into an acoustic signal through an earphone or a loudspeaker. Therefore, the amplified sound is
It is re-supplied to the eardrum through the ear molding (otoplastic) inserted in the ar canal. It is possible to install the entire hearing aid in the ear molding, in which case it is called an in-ear hearing aid. Bone conduction hearing aids are rather rare and therefore only used in special cases. In this case, the output signal of the amplifier of the hearing aid is not converted to sound, but to mechanical vibration via bone conduction headphones or a vibrator. This vibration of the bone conduction headphones normally contacts the mastoid and travels through the skull directly to the inner ear in the form of mechanical vibrations. Here, each nerve stimulation, that is, each sensitivity to sound is generated.

A hearing aid of the kind described at the outset is WO92 / 038
No. 393, the output transducers are formed by coils which generate respective alternating magnetic fields which are reciprocal to the acoustic input signal. This magnetic field cooperates with a small permanent magnet attached directly to the eardrum or one of the small bones (hammer, incus, stapes) by a biocompatible adhesive. Under the influence of an alternating magnetic field, magnets vibrate all human hearing organs and thus give rise to auditory sensations.

[0004]

This principle of electromagnetic acoustic amplification, in particular, significantly improves the hearing ability compared to the capabilities of conventional hearing aids such as natural fidelity to sound, low distortion and avoidance of acoustic feedback hazards. increase.

However, the known solutions lead to major problems. If inconsistencies in the impedance of the user's auditory organ in the region of the transmitted frequency range occur due to individual differences or as a result of illness, the vibration amplitude of the magnet will not be able to follow the generated magnetic field. The result of such interference is an auditory sensation that does not correspond to the amplitude curve of the input signal.

The object of the present invention is to avoid this drawback and to provide a hearing aid of the kind described at the outset in which the impedance of the hearing organ of the user, which is not uniform over the frequency range to be transmitted, is taken into account. You can

[0007]

This object is achieved according to the invention by a hearing aid in which a reference microphone is placed in front of the eardrum and is connected to a signal processing circuit.

With the aid of a permanent magnet vibrated by the coil, the eardrum vibrates like a thin film and radiates a small portion of the transmitted energy in the form of acoustic waves to the ear canal. Acoustic pressure is thus generated in front of the eardrum, which is detected by the reference microphone and corresponds more or less to the auditory sensation, and in the presence of the aforesaid disturbances, comprises the respective detected amplitude change.

When the reference microphone signal influences the processing of the input signal, such disturbances can thus be compensated. In this regard, it is possible not only to ensure an auditory sensation that corresponds considerably to the input sound signal, but also to emphasize or attenuate certain frequency ranges in order to improve the understanding of speech in response to individual hearing loss. Is.

The features of claim 2 greatly simplify the construction of the hearing aid.

The features of claim 3 make it possible to process the input signal, exactly adapt to the individual needs of the user and have a very complex control characteristic in a relatively simple device for a hearing aid circuit. The advantage is that it can be achieved regardless.

A feature of claim 4 is that it makes it possible to achieve very complex processing of the input signal. These can be adapted according to the needs changed by the changes in the programs stored in the logic array.

A feature of claim 5 or 6 is that it enables a highly complex processing of the input signal in a purely analog way.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in detail with reference to the accompanying drawings, which schematically show in FIGS. 1 to 3 various embodiments of a hearing aid according to the invention. The embodiment according to FIG. 1 shows the principle structure of a hearing aid according to the invention. Preamplifier 2
A microphone 1 to which is connected is provided. It is connected to the signal processing circuit 3 on the output side. The processing circuit 3 may be assembled, for example, by a voltage controlled amplifier, a voltage controlled filter, or a combination of such modules coupled to a control circuit connected to the control input of the processing circuit 3.

The signal processing circuit 3 has a power amplifier 4 on the output side.
Which is arranged on the output side in the ear 30 and is connected to the transducer 5 formed by a coil.

This transducer 5 cooperates with a permanent magnet 6 placed on the eardrum of the user or implanted in the ear 30. The auditory system is also made to oscillate, and as a result the eardrum is made to oscillate due to the alternating magnetic field generated by the transducer.

Furthermore, the reference microphone 7 is arranged in the ear 30, for example the external auditory canal, which is connected to an amplifier 8 whose output is connected to the control input of the signal processing circuit 3.

The control circuit of the signal processing circuit 3 may comprise a summing element for coupling in the negative feedback signal of the reference microphone 7 coming from the amplifier 8 and / or the rectifier.

As a result of the vibrations of the permanent magnets, the user's hearing organs are also made to vibrate in different ways, as well as the eardrum. It works like a thin film,
The vibration of the sound occurs in the eardrum zone, is detected by the reference microphone 7, and is converted into an electric signal.

If inconsistencies in the impedance of the user's hearing organs occur in the audible range as a result of individual differences or illness, these are recognized by the signal received by the reference microphone 7. After amplification of the signal of the reference microphone 7, the same is fed to the signal processing circuit 3 and the processing of the signal received by the microphone 1 is thus influenced in order to offset the maximum audible range mismatch.

In the embodiment according to FIG. 2, the signal processing circuit 3 is provided with a multi-channel device. Filters 9 and 10 connected to the input of the signal processing circuit 3 are provided in each branch path.
And signal processing stages 11 and 12 connected in series therewith. The outputs of these signal processing stages 11 and 12 are connected to the inputs of the adder circuit 13, and the outputs thereof are connected to the power amplifier 4.

In this embodiment, the output of the amplifier 8 connected to the reference microphone 7 has a number of filters 14, 15 switched in parallel corresponding to the number of branches of the signal processing circuit 3.
Connected to. The output of the filter is the signal processing stage 11, 12
Connected to the control input. Filters 9,14 and 10,15
Is assigned to each branch of the signal processing circuit 3,
All 11 and 12 have the same characteristics.

With the hearing aid according to FIG. 2, a very favorable hearing gain can be achieved even in the case of very complex hearing impairments.

In the embodiment according to FIG. 3, the signal processing circuit 3 is provided with a voltage control filter 21 as described, for example, in patent application A228 / 90. Non-linear transfer functions are frequently needed in such devices of the signal processing circuit 3.

The voltage control filter 21 is controlled by the amplifier 8
A programmable logic array 19 through a filter 14 connected to the rectifier 16, a rectifier 16 connected to its output, a low pass filter 17 and an analog-digital converter 18.
, Where the incoming digital signals are processed according to a stored program.

The output of the logic array 19 is connected directly to the control input of the control filter 21 as shown by the dashed line, or via a digital-to-analog converter 20 which converts the digital output of the logic array 19 into respective analog signals. be able to.

As shown in FIG. 3, the signal processing circuit 3 is provided with some branches similar to FIG. Each branch point is provided in the voltage control filter 21. In this case, as many parallel control branches as the number of branches of the signal processing circuit 3 can be connected to the amplifier 8. Each control branch is provided with a filter, a rectifier 16, a low pass filter 17, an analog-digital converter 18 and a programmable logic array 19, which is connected to the amplifier 8 and is connected to the branch shown in broken lines in FIG. Will be arranged accordingly. The individual channels are combined by a summing stage 31 before reaching the power amplifier.

The illustrated configuration of the module connected to the amplifier 8 ensures the non-linear transfer function required to drive the voltage controlled filter 21. The determination of the absolute value of the signal is made through the rectifier 16. Low-pass filter
After integration of the rectified signal in 17, it is processed according to the program written in logic array 19. The output signal causes the voltage controlled filter 21 to be controlled in a branch that is effective for the desired signal.

The advantage of the embodiment according to FIG. 3 is that even very complicated feedback control is possible, nevertheless the overall system is composed of a relatively simple device. The desired signal path through the microphone 1, the preamplifier 2, the signal processing circuit 3, the power amplifier and the transducer 5 operates in a purely analog way and is therefore not given the delay caused by digitization.

Complex feedback control is necessary when the magnet is attached, for example, to a part of the middle ear (hammer, incus, stapes). The information supplied by the eardrum to the reference microphone 7 in this case is not the same as the information reaching the inner ear, because the impedances are different. It is also necessary to consider the stapidus reflex, which arises from some volume and is more frequency dependent. This requires each setting of feedback control or signal processing of the signal processing circuit 3.

If the magnet 8 is attached to the eardrum, it is necessary to consider the transmission from the eardrum via the middle ear to the inner ear, which is given some non-linearity.

The hearing aid according to FIG. 3 makes it possible to arrange the signal to be processed in the branch of the desired signal so that even very complex transfer functions are carried out.

A further possibility of connection with the circuit of FIG. 3 is to form the branch of the signal processing circuit 3 by a series connection of a filter and a voltage controlled amplifier in series instead of the voltage controlled filter 21, respectively. . In this case, the branch path filter of the signal processing circuit 3 is provided with characteristics corresponding to the characteristics of the filters 14 and 15 of each control branch path connected to the amplifier 8 (FIG. 3).

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of a hearing aid according to the present invention.

FIG. 2 is a block diagram of a second embodiment of a hearing aid according to the present invention.

FIG. 3 is a block diagram of a third embodiment of a hearing aid according to the present invention.

Claims (6)

[Claims] 1. A microphone arranged in a case, the microphone connected in series with at least one amplifier, a signal processing circuit such as a voltage controlled amplifier and / or a voltage controlled filter, and an output transducer. The output transducer produces an alternating magnetic field and in a hearing aid formed by a coil cooperating with a permanent magnet implanted or mounted in the eardrum or in the ear, such as between the eardrum and the pedicle of the malleus, a reference microphone. Is a hearing aid that is placed in front of the eardrum and is connected to a signal processing circuit. 2. Hearing aid according to claim 1, characterized in that the reference microphone is connected via a rectifier to the control input of the signal processing circuit, preferably to the negative feedback branch. 3. The signal processing circuit is provided with a plurality of branch paths connected to an input through a filter and connected to an output of the processing circuit through an adder circuit, and each branch path includes a signal processing stage. 2. A hearing aid according to claim 1, characterized in that the control input is connected via a filter to a reference microphone, the characteristic of which corresponds to the characteristic of the filter associated with each signal processing stage. 4. A series connection comprising a rectifier, a low-pass filter, an analog-digital converter and a programmable logic array is provided in the output circuit of the reference microphone, the series connection optionally via a digital-analog converter for signal processing. Hearing aid according to claim 1 or 2, characterized in that it is connected to the control input of the circuit. 5. A multi-channel processing circuit is provided, each branch of which has a voltage control filter,
The control input of the voltage control filter is connected to a rectifier, a low-pass filter, an analog-digital converter and a series connection consisting of a programmable logic array, which are connected to the reference microphone via the filter. A hearing aid according to claim 4, characterized in that 6. A multi-channel signal processing circuit is provided, each branch of which comprises a filter and a voltage controlled amplifier connected in series therewith, which comprises a rectifier, a low-pass filter, an analog-digital converter,
A hearing aid according to claim 4, characterized in that it comprises a programmable logic array, which is connected via a filter to a reference microphone, the characteristics of which correspond to the filter characteristics of each branch of the signal processing circuit.