US3928733A - Hearing aid control circuit for suppressing background noise - Google Patents

Hearing aid control circuit for suppressing background noise Download PDF

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Publication number
US3928733A
US3928733A US525552A US52555274A US3928733A US 3928733 A US3928733 A US 3928733A US 525552 A US525552 A US 525552A US 52555274 A US52555274 A US 52555274A US 3928733 A US3928733 A US 3928733A
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Prior art keywords
transistor
hearing aid
control circuit
low
signal
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Expired - Lifetime
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US525552A
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English (en)
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Fritz Hueber
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Viennatone GmbH
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Viennatone GmbH
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R25/00—Electric hearing aids
    • H04R25/50—Customised settings for obtaining desired overall acoustical characteristics
    • H04R25/502—Customised settings for obtaining desired overall acoustical characteristics using analog signal processing

Definitions

  • This switch is arranged to block trans 5 32 mission of the signal below a set threshold level of the I o n 1 s s 1 s s s s I a s s I s l u e
  • Field of Search 179/1 P, 107 R 01S the Switch [56] References Cited UNITED STATES PATENTS 10 Claims, 2 Drawing Figures 3,101,081 8/1963 Tomatis 179/107 R c 5 7 8 T 4 ⁇ 551 R HEARING AID CONTROL CIRCUIT FOR SUPPRESSING BACKGROUND NOISE
  • the present invention relates to improvements in a control circuit connected between a microphone and an emitter of a hearing aid.
  • the microphone receives an input signal and the circuit is arranged to transmit the input signal to an emitter, the circuit including a low-frequency channel comprising an initial amplifier connected to the microphone and a final amplifying transistor connected to the emitter.
  • the signal transmission is opened only when the input signal has reached a predetermined threshold level significantly higher than the level of theusual background noises.
  • Threshold value switching means are well known in the radio art to provide noise attenuation, quiet tuning, squelch, etcL Obviously, however, all of these circuits use the high-frequency carrier of the received signal as controlling criterion for switching the low-frequency transmission path in and out. However, since there is no high-frequency carrier in a hearing aid circuit, the control signal must come from the low-frequency signal itself. Up to now, circuits of this type could not be used in hearing aids because of the required circuit components and the low voltages used in hearing aids.
  • this difficulty has been overcome in the type of circuit described hereinabove by connecting a threshold switching means to the low-frequency channel and arranging it to block transmission of the input signal from the microphone to the'emitter below a predetermined threshold level of the signal, the low-frequency signal in the low-frequency channel controlling the switching means.
  • FIG. 1 is a graph illustrating the input-output characteristics of a desirable hearing aid
  • FIG. 2 is a circuit diagram illustrating the invention.
  • FIG. 1 While there is a linear ratio between the input decible level p, and the output decible level p in conventional hearing aids even when the input noise level is low (see broken line), the control circuit illustrated in FIG. 2 will suppress any output signal p, if the input noise level is smaller than threshold level ,0" Once the threshold value has been reached, the sound amplification will increase linearly (see full line) until the output decible level has reached its saturation value at level p'
  • FIG. 2 there is shown microphone 1 connected to the base contact of output stage amplifying transistor T condenser C potentiometer 3 and amplitier 2 being interposed between transistor T and microphone 1.
  • the collector of the transistor is connected to the positive terminal of a battery, which provides the voltage source for the hearing aid, earphone or emitter 4 being interposed between the transistor collector and the battery terminal, while the transistor emitter is directly connected to the negative terminal of the battery.
  • Amplifier 2 and transistor T form a low-frequency channel.
  • the collector-emitter path of threshold switching transistor T is connected between the base contact of output stage transistor-T andthe positive terminal of the battery, resistance R being interposed between the base contact and the connector emitter path of transistor T Condenser C is connected in parallel to transistor T
  • the output of amplifier 2 is connected to the base contact of amplifying transistor T condenser C being interposed between the amplifier output and the transistor base contact.
  • Potentiometer 5, with two slide contacts 7, 8, connects the collector of transistor T to the positive battery terminal while the emitter of transistor T is connected directly to the negative battery terminal.
  • the base contact of switching transistor T may be connected either to first slide contact 7 by a first pair of terminals of switch unit 6 or to second slide contact 8 by a second pair of terminals of the switch unit, condenser C being interposed between the base contact of transistor T and the switch unit. Furthermore, the base contact of transistor T may be connected to the negative battery terminal by a. third pair of terminals of switch unit 6, resistance R being interposed between the switch unit and the negative battery terminal.
  • the base contact of amplifying transistor T is connected to the connecting point between resistances R and R, which are connected in series between the collector of transistor T and the negative battery terminal, resistance R being interposed between the base contact of transistor T and the connecting point between resistances R and R Resistance R is connected between this connecting point and the base contact of switching transistor T.
  • the low-frequency signal received by microphone 1 is amplified at 2, the loudness of the signal being individually adjustable by potentiometer 3, and the adjusted, amplified signal is transmitted through condenser C to the base contact of output stage transistor T
  • the input signal to the microphone is negligible, i.e. caused primarily or exclusively by ambient noises
  • the voltage transmitted to switching transistor T via voltage dividers R R and resistance r is such that the switching transistor is blocked.
  • the base contact of output stage transistor T also receives no appreciable voltage via resistance R and is also blocked. Therefore, earphone or emitter 4 produces no output signal.
  • Point 9 of the circuit is approximately at full working voltage.
  • Amplifying transistor T as well as amplifier 2 are constantly in operation, independently of the level of the input signal to the microphone.
  • the low-frequency signal at the base contact of transistor T is practically independent of the adjustment of potentiometer 3.
  • the low-frequency signal coming from transistor T is trans mitted through operating resistance by the first pair of terminals of switch unit 6 and condenser C to the base contact of switching transistor T This signal is rectified in the base contact-emitter path of this transistor and opens the transistor as soon as the signal has reached a predetermined amplitude. A small input signal will not reach this amplitude.
  • the level of the input signal causing the flip-flop circuit to become conductive depends on the amplitude of the low-frequency signal at the base contact of switching transistor T Since switching unit 6 may be operated by the hard-of-hearing person, the operator can adjust the threshold of the circuit to the ambient acoustical conditions. In very noisy surroundings, the operator will set the threshold at a higher level since the operating noise (speech) will then be louder, too, the automatic reaction of a speaker being to adjust his voice to the surrounding noise so as to be intelligible.
  • switching unit 6 When switching unit 6 is adjusted to the illustrated position to make the uppermost pair of terminals operative, operating resistance 5 will make only a small portion of the amplified signal voltage effective at switching transistor T In this position, the input signal must have a very high level to open transistor T On the other hand, the entire signal voltage will be transmitted by resistance 5 in the central position so that transistor T will become conductive even when the level of the input signal is relatively low.
  • the lowest pair of terminals of switching unit 6 is in operation, the voltage coming from resistance R will keep transistor T constantly open, i.e. the threshold switch is inoperative. In this position of the switching unit, the circuit operates with a conventional hearing aid with linear amplification.
  • the described circuit does not essentially differ in its requirement for components from other hearing aid circuits, for instance conventional hearing aids with automatic adjustments of noise level, and it may readily be built into hearing aids of conventional size.
  • threshold value switch has been illustrated in connection with the circuit of a conventional hearing aid, it could also be combined with other types of control circuit for hearing aids.
  • a hearing aid with the control circuit of the present invention operates very economically since the output stage, which normally consumes about 60 to of the entire current requirements, is switched on only when an input signal of a predetermined threshold value is present.
  • a control circuit connected between a microphone and an emitter of a hearing aid, the microphone receiving an input signal and the circuit being arranged to transmit the input signal to the emitter, and the circuit including a low-frequency channel comprising a signal amplifier connected to the microphone and an output stage amplifying transistor connected to the emitter, the improvement of a threshold switching means connected to the low-frequency channel and arranged to block transmission of the input signal from the microphone to the emitter below a predetermined threshold level of the signal, the low-frequency signal in the low-frequency channel controlling the switching means.
  • the low-frequency channel comprising at least one transistor and the threshold switching means being connected to the transistor.
  • the transistor being the amplifying transistor connected to the emitter of the hearing-aid.
  • the threshold switching means comprising a switching transistor having a collector-emitter path, and the low-frequency channel comprising at least one transistor having a base contact, the collector-emitter path being connected to the base contact.
  • the transistor in the low-frequency channel being the amplifying transistor.
  • the switching transistor and the low-frequency channel transistor connected thereto constituting a bistable flip-flop stage.
  • the amplifier having an output, a further amplifying transistor having an input and an output, the output of the amplifier transmitting alternating circuit to the input of the further amplifying transistor, and the output of the further amplifying transistor being connected to the switching transistor.
  • a decible adjusting means connected between the amplifier and the further amplifying transistor, the high point of the decible adjusting means transmitting alternating current to the input of the further amplifying transistor.
  • a resistance connected between the further amplifying transistor and the switching transistor for transmitting a control voltage to the switching transistor, and means for adjusting the control voltage whereby the threshold value may be adjusted.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Neurosurgery (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
US525552A 1973-11-21 1974-11-20 Hearing aid control circuit for suppressing background noise Expired - Lifetime US3928733A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT975773A AT324460B (de) 1973-11-21 1973-11-21 Hörgerateschaltung

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US3928733A true US3928733A (en) 1975-12-23

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US525552A Expired - Lifetime US3928733A (en) 1973-11-21 1974-11-20 Hearing aid control circuit for suppressing background noise

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US (1) US3928733A (da)
AT (1) AT324460B (da)
CH (1) CH580899A5 (da)
DE (1) DE2452998C2 (da)
DK (1) DK147870C (da)
GB (1) GB1452564A (da)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4405831A (en) * 1980-12-22 1983-09-20 The Regents Of The University Of California Apparatus for selective noise suppression for hearing aids
US4622440A (en) * 1984-04-11 1986-11-11 In Tech Systems Corp. Differential hearing aid with programmable frequency response
US4750207A (en) * 1986-03-31 1988-06-07 Siemens Hearing Instruments, Inc. Hearing aid noise suppression system
US4759071A (en) * 1986-08-14 1988-07-19 Richards Medical Company Automatic noise eliminator for hearing aids
US4790018A (en) * 1987-02-11 1988-12-06 Argosy Electronics Frequency selection circuit for hearing aids
US4941179A (en) * 1988-04-27 1990-07-10 Gn Davavox A/S Method for the regulation of a hearing aid, a hearing aid and the use thereof
WO1990010363A3 (en) * 1989-03-02 1990-11-29 Ensonic Corp Power efficient hearing aid
US5046102A (en) * 1985-10-16 1991-09-03 Siemens Aktiengesellschaft Hearing aid with adjustable frequency response
EP0483701A3 (en) * 1990-10-30 1993-01-20 Ascom Audiosys Ag Method of noise reduction in hearing aids
US6072885A (en) * 1994-07-08 2000-06-06 Sonic Innovations, Inc. Hearing aid device incorporating signal processing techniques
US6212275B1 (en) * 1998-06-30 2001-04-03 Lucent Technologies, Inc. Telephone with automatic pause responsive, noise reduction muting and method
US6359992B1 (en) * 1997-02-06 2002-03-19 Micro Ear Technology Acoustics conditioner
US6480610B1 (en) 1999-09-21 2002-11-12 Sonic Innovations, Inc. Subband acoustic feedback cancellation in hearing aids
US6757395B1 (en) 2000-01-12 2004-06-29 Sonic Innovations, Inc. Noise reduction apparatus and method
US20070282392A1 (en) * 2006-05-30 2007-12-06 Phonak Ag Method and system for providing hearing assistance to a user
US8085959B2 (en) 1994-07-08 2011-12-27 Brigham Young University Hearing compensation system incorporating signal processing techniques
US20140219484A1 (en) * 2007-12-13 2014-08-07 At&T Intellectual Property I, L.P. Systems and Methods Employing Multiple Individual Wireless Earbuds for a Common Audio Source
US8976991B2 (en) 2001-08-10 2015-03-10 Hear-Wear Technologies, Llc BTE/CIC auditory device and modular connector system therefor
CN106254999A (zh) * 2016-07-20 2016-12-21 瑞声声学科技(深圳)有限公司 麦克风放大器电路
US10887706B2 (en) 2015-06-29 2021-01-05 Hear-Wear Technologies LLC Transducer modules for auditory communication devices and auditory communication devices

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2276756A1 (fr) * 1974-06-24 1976-01-23 Audibel Perfectionnement aux appareils de correction auditive
FR2416610A2 (fr) * 1978-02-07 1979-08-31 Audibel Perfectionnement aux appareils de correction auditive
AT396045B (de) * 1987-06-26 1993-05-25 Viennatone Gmbh Hoergeraet
GB2211701A (en) * 1987-10-27 1989-07-05 Kevin Stanley Fuller An audio frequency sensing switch
DE3802903A1 (de) * 1988-02-01 1989-08-10 Siemens Ag Einrichtung zur uebertragung von sprache
JP2656306B2 (ja) * 1988-07-05 1997-09-24 株式会社東芝 電話機
EP1086607B2 (en) † 1998-06-08 2012-04-11 Cochlear Limited Hearing instrument

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3101081A (en) * 1960-02-15 1963-08-20 Ile D Etudes Et De Brevets Mot Apparatus for the conditioning of the auditory lateralization

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3101081A (en) * 1960-02-15 1963-08-20 Ile D Etudes Et De Brevets Mot Apparatus for the conditioning of the auditory lateralization

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4405831A (en) * 1980-12-22 1983-09-20 The Regents Of The University Of California Apparatus for selective noise suppression for hearing aids
US4622440A (en) * 1984-04-11 1986-11-11 In Tech Systems Corp. Differential hearing aid with programmable frequency response
US5046102A (en) * 1985-10-16 1991-09-03 Siemens Aktiengesellschaft Hearing aid with adjustable frequency response
US4750207A (en) * 1986-03-31 1988-06-07 Siemens Hearing Instruments, Inc. Hearing aid noise suppression system
US4759071A (en) * 1986-08-14 1988-07-19 Richards Medical Company Automatic noise eliminator for hearing aids
US4790018A (en) * 1987-02-11 1988-12-06 Argosy Electronics Frequency selection circuit for hearing aids
US4941179A (en) * 1988-04-27 1990-07-10 Gn Davavox A/S Method for the regulation of a hearing aid, a hearing aid and the use thereof
WO1990010363A3 (en) * 1989-03-02 1990-11-29 Ensonic Corp Power efficient hearing aid
EP0483701A3 (en) * 1990-10-30 1993-01-20 Ascom Audiosys Ag Method of noise reduction in hearing aids
US8085959B2 (en) 1994-07-08 2011-12-27 Brigham Young University Hearing compensation system incorporating signal processing techniques
US6072885A (en) * 1994-07-08 2000-06-06 Sonic Innovations, Inc. Hearing aid device incorporating signal processing techniques
US6359992B1 (en) * 1997-02-06 2002-03-19 Micro Ear Technology Acoustics conditioner
US6442279B1 (en) 1997-02-06 2002-08-27 Micro Ear Technology, Inc. Acoustic conditioner
US6212275B1 (en) * 1998-06-30 2001-04-03 Lucent Technologies, Inc. Telephone with automatic pause responsive, noise reduction muting and method
US6480610B1 (en) 1999-09-21 2002-11-12 Sonic Innovations, Inc. Subband acoustic feedback cancellation in hearing aids
US20040125973A1 (en) * 1999-09-21 2004-07-01 Xiaoling Fang Subband acoustic feedback cancellation in hearing aids
US7020297B2 (en) 1999-09-21 2006-03-28 Sonic Innovations, Inc. Subband acoustic feedback cancellation in hearing aids
US6757395B1 (en) 2000-01-12 2004-06-29 Sonic Innovations, Inc. Noise reduction apparatus and method
US8976991B2 (en) 2001-08-10 2015-03-10 Hear-Wear Technologies, Llc BTE/CIC auditory device and modular connector system therefor
US9591393B2 (en) 2001-08-10 2017-03-07 Hear-Wear Technologies, Llc BTE/CIC auditory device and modular connector system therefor
US20070282392A1 (en) * 2006-05-30 2007-12-06 Phonak Ag Method and system for providing hearing assistance to a user
US20140219484A1 (en) * 2007-12-13 2014-08-07 At&T Intellectual Property I, L.P. Systems and Methods Employing Multiple Individual Wireless Earbuds for a Common Audio Source
US10499183B2 (en) * 2007-12-13 2019-12-03 At&T Intellectual Property I, L.P. Systems and methods employing multiple individual wireless earbuds for a common audio source
US10887706B2 (en) 2015-06-29 2021-01-05 Hear-Wear Technologies LLC Transducer modules for auditory communication devices and auditory communication devices
CN106254999A (zh) * 2016-07-20 2016-12-21 瑞声声学科技(深圳)有限公司 麦克风放大器电路
CN106254999B (zh) * 2016-07-20 2019-03-05 瑞声声学科技(深圳)有限公司 麦克风放大器电路

Also Published As

Publication number Publication date
AT324460B (de) 1975-09-10
DK147870B (da) 1984-12-24
DK147870C (da) 1985-06-24
CH580899A5 (da) 1976-10-15
DE2452998A1 (de) 1975-05-22
DK602174A (da) 1975-07-21
DE2452998C2 (de) 1983-09-01
GB1452564A (en) 1976-10-13

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