EP0209894A2 - Méthode pour la suppression de rétroaction dans des dispositions électro-acoustiques et dispositif pour la mise en oeuvre de cette méthode - Google Patents

Méthode pour la suppression de rétroaction dans des dispositions électro-acoustiques et dispositif pour la mise en oeuvre de cette méthode Download PDF

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Publication number
EP0209894A2
EP0209894A2 EP86110117A EP86110117A EP0209894A2 EP 0209894 A2 EP0209894 A2 EP 0209894A2 EP 86110117 A EP86110117 A EP 86110117A EP 86110117 A EP86110117 A EP 86110117A EP 0209894 A2 EP0209894 A2 EP 0209894A2
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EP
European Patent Office
Prior art keywords
channels
microphones
signals
feedback
phase
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP86110117A
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German (de)
English (en)
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EP0209894A3 (fr
Inventor
Dirk Schmidt-Enzmann
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Individual
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Individual
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Publication date
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Publication of EP0209894A2 publication Critical patent/EP0209894A2/fr
Publication of EP0209894A3 publication Critical patent/EP0209894A3/fr
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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
    • H04R3/00—Circuits for transducers
    • H04R3/02—Circuits for transducers for preventing acoustic reaction, i.e. acoustic oscillatory feedback

Definitions

  • the microphones are in most cases near the loudspeakers, which reproduce the speech signals picked up by the microphones, i.e. the microphones are located within earshot of the speakers. It is known that because the amplified sound of the loudspeaker also hits the microphone itself, feedback phenomena can occur which lead to whistling or humming tones in the loudspeakers or to speech distortion. In order to avoid such disturbing feedbacks, various proposals have already been made which are based on limiting the volume, or filtering out or suppressing the feedback frequency when feedbacks occur. On the one hand, these known devices have undesirable side effects and, on the other hand, do not lead to complete suppression of feedback, so that they require constant operation by very experienced operators.
  • the invention relates to a method and a device for suppressing the feedback in the electroacoustic systems in which microphones are arranged within earshot of loudspeakers.
  • the object on which the invention was based was to suppress the feedback phenomena in such installations with other, substantially simplified means.
  • the solution to this problem is that the output signals of the microphone, or the microphones, are given on two channels, offset from one another in phase and the two signals are combined in different strengths and fed to the loudspeaker or the loudspeakers as an input signal.
  • the best effect is obtained if the two signals are offset by 180 °.
  • a device for carrying out the above-mentioned method according to the invention is characterized in that two mutually parallel channels are connected to the output of a microphone, in which one channel a phase shifter adjustable in phase shift is arranged and both channels are interconnected again with the inclusion of a control device in one of the Channels.
  • an operational amplifier is arranged in each of the two channels and the two operational amplifiers are connected to one another in such a way that the phase positions of the signals in the two channels are opposite one another.
  • the invention is based on the fact known per se that if two signals of the same frequency meet in phase opposition, these signals can be completely or almost completely extinguished. It has now surprisingly been found that if one of the two signals meeting in phase opposition is significantly weaker than the other signal, on the one hand there is no extinction which interferes with speech reproduction, but on the other hand the tendency to feedback phenomena is very considerably reduced. Will that If the signal is amplified in the opposite phase, the security of feedback increases very strongly, whereas an effect can be observed with voice or vocal signals which corresponds to the effect of a high and low pass filter, i.e. does not have a negative but a positive effect on the speech or the vocals.
  • Audible extinctions only occur if the portion of the second, out-of-phase signal is added too strongly. But such a strong addition of gegenphesigen signal is not required to provide sufficient feedback - to achieve security. Rather, in order to achieve feedback security, the second, anti-phase signal can be mixed in to such an extent that the speech or vocal reproduction is not impaired.
  • loudspeaker system is to be understood very generally. It includes e.g. also hearing aids. As is known, these can also cause feedback between the narrow-band microphone and the loudspeaker (receiver) under unfavorable conditions, which are advantageously eliminated by the present invention.
  • a speech signal originating from a microphone 1 is split into two at point 2 Channels 3 and 4 shared.
  • the channel 4 there is a phase shifter 5, which can be adjusted so that the phase is rotated by 180 °, so that the phase in channel 4 is opposite to the phase in channel 3.
  • a control device 6 in channel 4 by means of which it is possible to make the signal in channel 4 significantly weaker than the signal transmitted in channel 3.
  • the two channels 3 and 4 are combined again and the signals are fed to a loudspeaker 8 via an amplifier (not shown).
  • the additional signal in channel 4 can be set by means of the control device 6 in such a way that it is considerably weaker than the signal transmitted in channel 3 and is nevertheless sufficient to prevent feedback.
  • the input transformer Tr1 can also be omitted.
  • the signal is again divided into two channels, which are denoted by 3 'and 4' in FIG. 2 and which, as is readily apparent, are constructed completely symmetrically.
  • the first channel 3 ' there is an operational amplifier V1 in the usual switching mode with resistors R11, R12, R13, R14 and R15.
  • the second channel 4 ' there is also an operational amplifier V2 in the usual circuit with resistors R21, R22, R23, R24 and R25.
  • the difference between the two channels 3 'and 4' is that the two operational amplifiers V1 and V2 are connected to one another in such a way that the output signals of the operational amplifiers V1 and V2 are opposite in phase.
  • a control device R10 is arranged in the channel 4 'carrying the phase signal, so that the signal present at the output terminal A2 of the circuit, which is opposite in phase to the signal present at the output terminal A1, is compared to the signal at the control device R10 Output terminal A1 can be significantly weakened. The tendency for feedback is suppressed by mixing the two signals.
  • the resulting output signal is picked up for its balancing via an output transformer Tr2 with the output terminals al, a2 and a3. If a balancing of the output signal is not necessary, this output transformer Tr2 can also be omitted.
  • the input terminal el of the input transformer Tr1 is connected to the output terminal a1 of the output transformer Tr2 via a shield S.
  • a microphone can be followed by a device according to the invention, whereupon only the signals from the different microphones are mixed, or the signals from the microphones can first be mixed together in the mixer and then to Suppression of feedback a device according to the invention can be turned on in the output line of the mixer.
  • the first way has the advantage that the feedback tendency can be different for the different microphones, so that there is the possibility here to set the device for each microphone in such a way that feedback is avoided without the sound signal being impaired. It is also important that different musical performances are very differently sensitive to the effect on the sound quality that may occur through the device according to the invention, so that it is possible for the different microphones, depending on whether they transmit speech, singing or instrumental music to mix the antiphase signal in different strengths.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Interconnected Communication Systems, Intercoms, And Interphones (AREA)
EP86110117A 1985-07-25 1986-07-23 Méthode pour la suppression de rétroaction dans des dispositions électro-acoustiques et dispositif pour la mise en oeuvre de cette méthode Withdrawn EP0209894A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19853526591 DE3526591A1 (de) 1985-07-25 1985-07-25 Verfahren zur unterdrueckung der rueckkopplung in elektroakustischen anlagen
DE3526591 1985-07-25

Publications (2)

Publication Number Publication Date
EP0209894A2 true EP0209894A2 (fr) 1987-01-28
EP0209894A3 EP0209894A3 (fr) 1988-01-13

Family

ID=6276718

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86110117A Withdrawn EP0209894A3 (fr) 1985-07-25 1986-07-23 Méthode pour la suppression de rétroaction dans des dispositions électro-acoustiques et dispositif pour la mise en oeuvre de cette méthode

Country Status (5)

Country Link
EP (1) EP0209894A3 (fr)
JP (1) JPS6271396A (fr)
DE (1) DE3526591A1 (fr)
DK (1) DK352886A (fr)
ES (1) ES2000559A6 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2630611A1 (fr) * 1988-04-22 1989-10-27 Bistagne Isabelle Procedes et dispositifs pour eviter les sifflements dus a des oscillations entretenues dans une boucle electro-acoustique
US4879749A (en) * 1986-06-26 1989-11-07 Audimax, Inc. Host controller for programmable digital hearing aid system
WO1990005436A1 (fr) * 1988-11-10 1990-05-17 Nicolet Instrument Corporation Suppression de l'effet larsen dans des protheses auditives de traitement de signaux numeriques
GB2240007A (en) * 1990-01-16 1991-07-17 Pioneer Electronic Corp Sound system with howling-prevention function
EP0613319A1 (fr) * 1993-02-23 1994-08-31 France Telecom Dispositif multicapteurs de prise de son et de traitement du signal associé
US7945057B2 (en) 2005-02-25 2011-05-17 Ferdos Innovations LLC Procedure and device for linearizing the characteristic curve of a vibration signal transducer such as a microphone

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK159357C (da) * 1988-03-18 1991-03-04 Oticon As Hoereapparat, navnlig til anbringelse i oeret
DE102010044917B4 (de) 2010-09-09 2015-01-08 Iav Gmbh Ingenieurgesellschaft Auto Und Verkehr Verfahren zur Vermeidung akustischer Rückkopplungen
DE102012008557B4 (de) 2012-03-16 2018-09-13 Iav Gmbh Ingenieurgesellschaft Auto Und Verkehr Verfahren zur Rückkopplungsunterdrückung in elektroakustischen Systemen

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3105877A (en) * 1960-09-12 1963-10-01 Itt Circuit for canceling oscillating in public address systems
HU169185B (fr) * 1974-06-05 1976-10-28
HU172630B (hu) * 1976-09-14 1978-11-28 Elektroakusztikai Gyar Sistema ozvuchenija s malen'koj sklonnost'ju k vozbuzhdeniju
US4064462A (en) * 1976-12-29 1977-12-20 Dukane Corporation Acoustic feedback peak elimination unit
DE2738339A1 (de) * 1977-08-25 1979-03-01 Bosch Gmbh Robert Hoergeraeteverstaerker
DE2807452A1 (de) * 1978-02-22 1979-08-23 Uwe Zink Rueckkopplungsausschalter

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4879749A (en) * 1986-06-26 1989-11-07 Audimax, Inc. Host controller for programmable digital hearing aid system
FR2630611A1 (fr) * 1988-04-22 1989-10-27 Bistagne Isabelle Procedes et dispositifs pour eviter les sifflements dus a des oscillations entretenues dans une boucle electro-acoustique
WO1990005436A1 (fr) * 1988-11-10 1990-05-17 Nicolet Instrument Corporation Suppression de l'effet larsen dans des protheses auditives de traitement de signaux numeriques
US5091952A (en) * 1988-11-10 1992-02-25 Wisconsin Alumni Research Foundation Feedback suppression in digital signal processing hearing aids
GB2240007A (en) * 1990-01-16 1991-07-17 Pioneer Electronic Corp Sound system with howling-prevention function
US5307417A (en) * 1990-01-16 1994-04-26 Pioneer Electronic Corporation Sound system with howling-prevention function
GB2240007B (en) * 1990-01-16 1994-05-11 Pioneer Electronic Corp Sound system with howling-prevention function
EP0613319A1 (fr) * 1993-02-23 1994-08-31 France Telecom Dispositif multicapteurs de prise de son et de traitement du signal associé
FR2702118A1 (fr) * 1993-02-23 1994-09-02 Le Tourneur Gregoire Dispositif multicapteurs de prise de son et de traitement du signal associé.
US7945057B2 (en) 2005-02-25 2011-05-17 Ferdos Innovations LLC Procedure and device for linearizing the characteristic curve of a vibration signal transducer such as a microphone
US20110235826A1 (en) * 2005-02-25 2011-09-29 Pakzad Samad F Procedure and device for linearizing the characteristic curve of a vibration signal transducer such as a microphone

Also Published As

Publication number Publication date
DE3526591A1 (de) 1987-01-29
ES2000559A6 (es) 1988-03-01
DK352886D0 (da) 1986-07-24
DK352886A (da) 1987-01-26
JPS6271396A (ja) 1987-04-02
EP0209894A3 (fr) 1988-01-13

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