GB1565701A - A remote hearing aid systems - Google Patents

Description

(54) REMOTE HEARING AID SYSTEMS (71) I, JOHN ARCHIBALD WENTWORTH-JESSOP, of British nationality, of 63, Burbage Road, London S.E.24, do hereby declare the invention for which I ray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to remote hearing aid systems and hearing aid receivers therefor.

A radio hearing aid system, suitable for example for classroom use by children at school who have poor hearing, comprises a microphone and radio transmitter, e.g. an FM transmitter, for use by the teacher, and a corresponding radio receiver for use by the child, the child's receiver including a built-in microphone, and means for acoustically reproducing via a hearing-aid transducer the signals received both by the radio receiver and by the microphone.

The use of such a system enables such a child to hear the teacher's voice as from close by, regardless of his position in the classroom and any noise sources which may be located between him and the teacher, because the signals are carried from the teacher to the child by radio.

The system also enables the child to hear his own voice and sounds coming from the other children.

According to this invention there is provided a remote hearing aid system comprising a microphone operatively coupled to the input of a radio or inductive-loop or line transmitter, and a hearing aid receiver comprising a radio or inductive-loop or line receiver able to receive transmissions from the transmitter and reproduce them acoustically via a hearing aid transducer, the receiver also comprising a further microphone, means for reproducing sounds received by the further microphone acoustically via the hearing-aid transducer, and an automatic volume control arrangement responsive to the strength of an audio signal derived from a transmission received from the transmitter to control the volume of reproduction of the sounds received by the further microphone.

The use of such an arrangement makes it possible to have the teacher's voice 'override' other sounds to a useful degree by means of the automatic volume control, and to avoid having the teacher's voice drowned when a large volume of sound is received by the further (local) microphone, while at the same time allowing the local sounds to be reproduced at full volume when the teacher's voice is not being received.

Suitably the AVC circuit is actuatable both by the audio signal derived from the received transmission, e.g. corresponding to the teacher's voice, and by an audio signal corresponding to the sounds received by the further microphone, e.g. the local sounds.

The invention also provides a hearing aid receiver for a remote hearing aid system as set forth above.

Embodiments of the invention are hereinafter described by way of example with reference to the accompanying drawings, in which like reference numerals indicate like parts throughout, and in which: Figure 1 is a block circuit diagram of a system comprising a transmitter and a receiver according to a first embodiment of the invention; and Figure 2 is a corresponding block diagram of a receiver according to an alternative embodiment.

Referring to the drawings, Figure 1 shows a radio hearing aid system in block circuit diagram form. It comprises an FM radio transmitter 1 of known kind, comprising a microphone 2 for use by a teacher, and a corresponding a.f. amplifier 3, FM transmitter 4 and aerial 5 connected to transmit FM radio signals 6 in response to sounds received by the microphone 2.

The system comprises a receiver unit 7, for use by a child of poor hearing in the ciass- room, comprising an aerial 8 and FM receiver 9 for FM radio signals 6, giving an a.f. output in line 10, corresponding to the transmitted and received radio signals. The receiver unit 7 is preferably portable and battery-powered and mounted in a casing or headset wearable by a user.

Receiver unit 7 also comprises a local microphone 11, connected to an input 12 of an amplifier 13 which is a variable-gain amplifier or which has at least one variable-gain stage, its gain being controllable by the voltage or current at its control input 14.

The output of amplifier 13 in line 15 is commoned with the FM receiver output in line 10, and the resulting mixed signal is connected both to the input 16 of an audio amplifier 17 which is connected at its output to an earpiece or other hearing-aid electroacoustic transducer 18., and also to the input 19 of an AVC circuit 20. AVC circuit 20 produces an AVC control voltage or current signal dependent on the level of the mixed a.f. signal connected to its input, and the AVC signal from the AVC circuit is connected by line 21 to control input 14 of amplifier 13. Receiver unit 7 is conveniently a light miniature portable battery-powered unit, so that it can be worn and used by a child without impairing mobility or convenience.

Transmitter 1 can also be a portable selfcontained unit.

The arrangement permits clear reception of the teacher's voice and full-volume reproduction of local sounds in the absence of a teacher's voice, while ensuring that the reproduced volume of the local sounds is reduced in the presence of the teacher's voice.

A suitable frequency for F.M. radio transmissions to be used in the example of a radio hearing aid system illustrated in the drawing is for example 174 MHz.

Of course, variations and modifications are possible. For example, any or all of modules 3, 4, 9, 13 and 17, in themselves of known type, can include further automatic gain control circuitry as may be desired. The radio link modules 4, 5, 8, 9 may be replaced for example by an inductive-loop transmitter-receiver system or even by a wired-distribution system, provided that the circuitry of the receiver unit includes means for reducing the reproduced volume of the 'local' sounds in response to the presence of 'distant' signals.

It should also be mentioned that the further microphone, i.e. the 'local' microphone associated with the hearing aid receiver, can but need not be built-in with the case and remainder of the hearing aid receiver unit. It can be a separate, e.g. lapel or tie-clip microphone connected to the receiver unit for example by a fixed or removably plugged-in cable.

An alternative embodiment of a receiver arrangement according to the invention is illustrated in block diagram form in Figure 2.

In this embodiment the antenna 8 for receiving the FM radio signals 6 (in this embodiment at about 174 MHz) is connected to an FM receiver 22 incorporating r.f. and i.f. circuits but not an audio detector. I.f. signals, suitably at 10.7 MHz, are coupled via line 23 to a second mixer 24, fed by an oscillator 25 suitably at a frequency of around 10.6 MHz, to produce a 2nd i.f. signal output in line 26, at a frequency of about 100 kHz, (in other embodiments suitably 30-150 kHz). After amplification by amplifier 27 the 2nd i.f.

signal is fed to an inductive-loop antenna 28 arranged to develop a signal 29 receivable only within a smaller range, for example about 4 feet, than the range of reception of the radio signals 6. A separate further receiver unit which is suitably of a form able to be worn by a child includes a pick-up coil 30 for the 2nd i.f. signals, and a receiver amplifier and audio detector 31. The output audio signal in line 10 is then mixed with a controlled signal from local microphone 11 and acoustically reproduced in transducer 18 in a similar manner to that used in the arrangement illustrated in Figure 1.

The arrangement shown in Figure 2 in effect splits the receiver of the radio hearing system into two parts. This can have practical advantage since the hearing aid amplifier/reproducer is often desired to be adjusted to the particular hearing loss of an individual user, while the radio receiver is not.

In a further alternative arrangement, a discriminator or detector, local microphone, and AVC arrangement according to the invention can be located in the intermediate receiver unit before the induction loop transmission stage. The gain-controlled voice-frequency signal is then modulated on the carrier and transmitted to the further receiver unit suitably worn or carried by the user, which in that case can comprise only a detector, amplifier and transducer. This arrangement can be used to reduce the complexity of the further receiver unit.

The modulation method used in the radio systems according to the embodiments of the invention which utilise an inductive-loop and further receiver unit, can of course be any of FM, AM, SSB or DSB, in each of the two transmission steps, but if as is conveniently the case the radio signal from the transmitter is FM it can be convenient to use FM also for the voice-frequency modulation of the signal transmitted via the inductive loop to the further receiver unit, thus (as in the example shown in Figure 2) avoiding the need for demodulation and remodulation.

WHAT I CLAIM IS: 1. A remote hearing aid system comprising a microphone operatively coupled to the input of a radio or inductive-loop or line transmitter, and a hearing aid receiver comprising a radio or inductive-loop or line receiver able to receive transmissions from the transmitter and reproduce them acoustically via a hearing aid transducer, the receiver also comprising a further microphone, means for reproducing sounds received by the further microphone acoustically via the hearing aid transducer, and an automatic volume control arrangement responsive to the strength of an audio signal derived from a transmission received from the transmitter to control the volume of reproduction of the sounds received by the further microphone.

2. A system according to claim 1, in which the automatic volume control arrangement is actuatable both by the audio signal derived from the received transmission and by an audio signal corresponding to the sounds received by the further microphone.

3. A system according to claim 1 or claim 2, in which the transmitter and receiver are a radio transmitter and radio receiver.

4. A system according to claim 3, in which the radio transmitter and receiver are an F.M. radio transmitter and receiver.

5. A system according to any one of the preceding claims, in which the receiver is portable and battery-powered and mounted in a casing or headset wearable by a user.

6. A system according to any one of the preceding claims, in which the further microphone is wearable by a user and connected with the remainder of the receiver by a fixed or removably plugged-in cable.

7. A remote hearing aid system according to any preceding claim, in which the receiver comprises a first receiver unit arranged to receive and re-transmit received transmissions from the transmitter, the retransmitted transmissions being in the form of a carrier signal in the frequency range 30-150 kHz modulated with a voicefrequency signal and being re-transmitted via an inductive-loop transmitter to a further receiver unit comprising a receiver and detector of the modulated carrier signal operatively coupled to the hearing aid transducer.

8. A remote hearing aid system according to claim 7, in which the transmitter and receiver are as defined in claim 4, and the first receiver unit comprises a converter for producing a frequency-modulated said carrier signal from the f.m. radio frequency signals.

9. A system according to claim 8, in which the radio frequency is substantially 174 MHz and the said carrier signal has a frequency of substantially 100 kHz.

10. A remote hearing aid system substantially as hereinbefore described with reference to Figure 1 of the accompanying drawing.

11. A remote hearing aid system substantially as hereinbefore described with reference to Figure 2 of the accompanying drawing.

12. A hearing aid receiver for a remote hearing aid system as claimed in claim 1, the receiver being as defined by any one of the

Claims (1)

1. preceding claims.