MXPA99010862A - Hearing aid having input agc and output agc - Google Patents

Abstract

A hearing aid has input AGC and output AGC using only one attack/release circuit and only one variable gain amplifier. An input AGC signal and an output AGC signal are summed and the summed signal, processed through the attack/release circuit, is used to control the gain of the variable gain amplifier.

Description

APPARATUS FOR AUDITORY PROSTHESIS THAT HAS AGC INPUT AND AGC OUTPUT BACKGROUND OF THE INVENTION The invention relates to an apparatus for hearing aids and more particularly relates to devices for hearing aids of the type q * u e have automatic gain control. { "AGC"). In a more immediate sense, the invention relates to devices for hearing aids that both have the AGC input and AGC output. Devices for hearing aids commonly have AGC input and AGC output, and at least one of both has a hearing aid device currently available. The AGC input is used for input compression, so the response of the hearing prosthesis circuit appropriately couples to the patient's auditory disorder. The AGC output is used to prevent the patient from discomfort caused by untimely loud noises, for example by the loud knocking of a door. However, in the auditory prosthesis device that has AGC input and AGC output, the circuit is susceptible to improper functioning. This is because this circuit uses two separate and independent AGC circuits. As a result, the circuits use a relatively high number of components and may exhibit a malfunction when the tolerances of those components are added wrongly. It should be advantageous to provide an apparatus circuit for a hearing aid and an apparatus for hearing aids that provides a patient with the advantages of both AGC inputs and AGC output while being simpler and less sensitive to tolerance variations of component-values. An object of the invention is to provide an apparatus circuit for hearing aids, and an apparatus for hearing aids, which has both AGC input and AGC output while using a relatively simple circuit. »Another object is, in general, to improve the devices for known hearing aids and device circuits for hearing aids. According to the invention, the AGC is carried out using a simple variable gain amplifier. This variable gain amplifier is controlled in response to two signals; one derived from the input side (microphone) of the device circuit for hearing aid and the other derived from the output side (receiver). Advantageously and in accordance with the preferred embodiment, the signals are combined and routed through a single-stranded ac / 1-iber ac circuit. As a result, the circuit is greatly simplified and becomes less sensitive to tolerance variations of component values.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood with reference to the accompanying exemplary and non-limiting drawings, in which: Figure 1 illustrates a known hearing aid apparatus having both AGC inlet and AGC outlet; And Figure 2 illustrates a preferred embodiment of the invention.

Detailed Description of the Preferred Modes The same element is always indicated by the same reference number in all the Figures, and the correspondence between the corresponding elements was indicated using printed reference numbers. In a known hearing aid apparatus currently sold by Starkey Laboratories, Inc., a microphone 2 is connected to the input of the microphone amplifier 4. The output of the microphone amplifier 4 is connected to the input of a variable gain amplifier, and the output of the variable gain amplifier 6 is connected to the input of a p re amp 1 ifi ca do r 8. The output of the preamplifier 8 is connected to the input of a variable gain amplifier 10 and the output of the amplifier of variable gain 10 is connected to the input of a power amplifier 12. The output of the power amplifier 12 is connected to a receiver 14. An AGC input network is formed by using the signal at the input of the gain amplifier variable 6 for controlling the gain of the variable amplifier 6. A variable resistor 16 connects the input of the variable gain amplifier 6 to the control circuit 18, which in turn is connected to a tie-in circuit that is / ibera 20. The start-up / 1-rae-ion circuit 20 is in turn connected to the gain control input of the variable gain amplifier. The functionality of this AGC input network will be expanded. An AGC network input is used to match the characteristics of a hearing aid device to the patient's disorder and the AGC input compresses the response of the system so that the wide range of sound amplitudes presented to the microphone 2 is mapped to the narrow range of amplitude that the patient's ear can accommodate. The threshold of the input network AGC is adjusted by the variation of the resistor 16, and the current compression is determined by the selection of characteristics of the control circuit 18. Conventionally, the control circuit 18 contains a rectifier and a non-linear amplifier. (both not shown), but this is not required; a person skilled in the art can readily provide suitable circuitry for the control circuit 18, once the nature of the patient's auditory disorder is known. The function of the circuit of 1 iberation / a t that 20 is to soften the signal that is used to vary the gain of the variable gain amplifier 6.

This softness function is carried out by the ratio of a "capacitor 20C" in the link circuit to / i ibration 20, and makes the gain of variable gain amplifier 6 a function of the transverse voltage of the capacitor 20C. As the transverse voltage of the capacitor 20C increases, the gain of the variable gain amplifier 6 decreases The resistor 20R1 'is connected in series between the control circuit 18 and the capacitor 20C The range in which the capacitor 20C charges ( the so-called "attack time" of the free / active circuit that 20) is therefore determined by the RC time constant or the 20R1 resistor and the 20C capacitor.A resistor 20R2 is located across the capacitor This creates a discharge path by which the capacitor 20C can be discharged through the resistor 20R2 The range in which the capacitor 20C discharges (the so-called "release time") is therefore determined by the RC time constant of resistor 20R2. The speed at which the capacitor 20C discharges (the so-called "release time") is therefore determined by the RC time constant of the resistor 20R2. Let it be assumed that the amplitude of sound to the microphone 2 increases sharply and that this increase causes an increased signal at the output of the control circuit 18. This increased amplitude will not immediately reduce the amplitude of the amplifier of variable amplitude 6 due to the transverse voltage of the capacitor 20C will increase to a less slow range (the attack time of the 1-year averaging / taque 20 is relatively slow). Preferably, the amplitude of the variable amplitude amplifier 6 should decrease slowly, as the transverse load of the capacitor 20C continues to increase.Also, let it be assumed that the amplitude of sound to the microphone 2 decreases sharply, causing a decremented signal at the output of the control 18. This abruptly decremented amplitude does not immediately increase the gain of the variable gain amplifier 6. This BS because the transverse voltage of capacitor 20C will decrease more slowly, this charging range being determined by the range at which capacitor 20 is discharged through the resistor 20R2, for example by the time released from the release circuit / at 20, that the time released is also relatively low.) For short, the release / attack circuit 18 smoothes the abrupt, the variations of short term in the AGC control voltage, these variations, if not smooth, should produce variations of g Drastic anancia in the amplifier of variable gain 6, that the variations must be uncomfortable for the p a c i in t e. A similar AGC network-hereinafter referred to as an AGC output network is used to control the gain of the variable gain amplifier 10. The purpose of the AGC output network protects the patient from the intense discomfort produced by sharply intense sounds. For example, if the patient engages in a low conversation and a door is closed with a loud bang, the increased sound level can suddenly damage the patient's remaining hearing. To prevent this, the gain of the variable gain amplifier is reduced rapidly (short attack time) when eg. Sound level increases rapidly. In the absence of more than high sound levels, the gain is then increased slowly (long release time). The threshold of the input network is adjusted by the variation of the resistor 22, and the current gain control scheme is determined by the selection of characteristics of the control circuit 24. With a clear advantage, the control circuit 24 contains a rectifier or a non-linear amplifier (both not shown) but this is not required; a person skilled in the art will easily be able to provide suitable circuitry for the control circuit 24. The circuit of 1 year to which it works 26 works the same as the circuit of which it operates., but with different attack and release times satisfies the intended application. The circuit illustrated in Fig. 1 has two sales windows larger. First, it is relatively expensive due to the number of parts required. Second, if the resistors and capacitors in the control circuits 20 and 24 do not have values in proper ratio each (and this can happen if the tolerances of these values are added incorrectly), the circuits can presenta malfunction Now back to Figure 2, the illustrated preferred embodiment of the invention has a microphone 2 ', a microphone amplifier 4', a variable gain amplifier 6 ', a preamplifier 8', a power amplifier 12 'and a receiver 14 '. These elements are identical to their counterparts in the circuit of Figure 1, and are connected to operate in the same way. In addition, the output of the amplifier circuit 1 to 20 'is connected to the gain control input of the variable gain amplifier 6'. One end of a variable resistor 16 'is connected to the input of the variable gain amplifier 6'. One end of a variable resistor 16 'is connected to the input of the variable gain amplifier 6' and the other end of the variable resistor 16 'is connected to the input of a control circuit 18'. (The control circuit 18 'operates identically to the control circuit 18). The end of a variable resistor 22 'is connected to the input of the power amplifier 12', and the other end of the variable resistor 22 'is connected to the input of a control circuit 24'. (The control circuit 24 'operates identically to the control circuit 24).

The signals to the outputs of the control circuits 18 'and 24' are added in an adder 28, which adds them together and produces a summed AGC signal.

The added AGC signal is then input to the 1-ration / taque 20 circuit. The preferred embodiment of the invention illustrated in Figure 2 includes the AGC input and AGC output, but the AGC is completed in a manner different from that in Figure 1. The threshold of the AGC input is established by the value of the variable resistor 16 ', and the threshold of the AGC output is established by the value of .the variable 22'. Then, the 'AGC input and output signals produced respectively by the control circuit 18' and the control circuit 241 are summed together to form a summed AGC signal, which then proceeds in the free / on-board circuit. 'which is used to vary the gain of the variable gain amplifier 6'. Therefore it can be seen that according to the preferred embodiment of the invention, the AGC input and output are implied by using only a variable gain amplifier and only a release circuit. This reduced cost and complexity and the avoided malfunction arises from incompatibility between the components and two release / attack circuits. According to the preferred embodiment of the invention, the circuit illustrated in Figure 2 is contained in a housing schematically illustrated with the reference number 30. While one or more preferred embodiments have been described in the foregoing, the scope of the invention is limited only by the following claims:

Claims (7)

1. An apparatus circuit for a hearing aid adapted to be connected to a microphone and a receiver comprises: a variable gain amplifier having an input, an output and a gain control input, the gain of the variable gain amplifier being determined by a electrical signal present at the input of the gain control, and the variable gain amplifier being connected in such a way that the electrical signals at its input are determined by electrical signals from the microphone; a power amplifier has an input and an output, the output being adapted for connection to a receiver, and the power amplifier being connected in such a way that the signals at its inputs are determined by signals at the output of the variable gain amplifier; an input network that responds to the electrical signals at the input of the variable gain amplifier and that produces an AGC input signal; an output network that responds to the electrical signals at the input of the power amplifier and produces an AGC output signal; an adder circuit connected to the input and output networks and producing a summed signal AGC; and a 1-way circuit connected between the summing circuit and the gain control input, the ion-to-ion circuit responds to the summed AGC signal and produces an electrical signal at the control input. of profit

2. The circuit of claim 1, further comprising a preamplifier connected between the output of the variable gain amplifier and the input of the power amplifier.

3. The circuit of claim 1, further comprising a microphone amplifier having an input adapted to be connected to a microphone and an output connected to the input of the variable gain amplifier. ¿

4. The circuit of claim 1, wherein the releasing circuit comprises a capacitor, wherein the aggregate AGC signal is used to charge the capacitor, and wherein the signal at the gain control input reflects the charge through the capacitor.

5. The circuit of claim 4, wherein the 1iber / ation circuit also comprises a load resistor and a discharge resistor, the load resistor being in series with the capacitor and the discharge resistor being in parallel with the load resistor. capacitor.

6. An apparatus for hearing aids having AGC input and AGC output, comprising ^: a microphone; a variable gain amplifier having an input, an output and a gain control input, the gain of the variable gain amplifier being determined by an electrical signal present in the gain control input, and the variable gain amplifier being connected in such a way that the electrical signals in their inputs are determined by electrical signals from the microphone; a receiver; a power amplifier having an output and an input, the output being connected to the receiver and the power amplifier being connected to those signals at its inputs that are determined by signals at the output of the variable gain amplifier; an input network that responds to the electrical signals at the input of the variable gain amplifier and that produce an input AGC signal; an output network that responds to electrical signals at the input of the power amplifier and produces an AGC output signal; an adder circuit connected to the input and output networks and producing a summed AGC signal; a free-to-air circuit connected between the summing circuit and the gain control input, the circuit of 1 ribe at / that responds to the summed AGC signal and which produces an electrical signal at the input of gain control; and a housing that contains the micro fp no, the receiver, the circuits and the networks.

7. An instrument circuit for a hearing aid having a variable gain amplifier, an AGC input and a compliant AGC output: means for deriving an AGC input signal; means for deriving an AGC output signal; means for adding the AGC input signal and the AGC output signal and thus producing a summed signal AGC; means for filtering the summed signal AGC and thus producing an AGC filtered signal; and means for adjusting the gain of the variable gain amplifier according to the filtered signal AGC.