EP0209894A2 - Method for suppressing feedback in electroacoustic installations and arrangement for carrying out this method - Google Patents
Method for suppressing feedback in electroacoustic installations and arrangement for carrying out this method Download PDFInfo
- 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
- Authority
- 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- Withdrawn
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/02—Circuits for transducers, loudspeakers or microphones 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.
Landscapes
- 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)
Abstract
Description
In Lautsprecheranlagen befinden sich die Mikrofone in den meisten Fällen in der Nähe der Lautsprecher, die die von den Mikrofonen aufgenommenen Sprachsignale verstärkt wiedergeben, d.h. die Mikrofone sind in Hörweite von den Lautsprechern angeordnet. Es ist bekannt, daß dabei, weil der verstärkte Ton der Lautsprecher auch das Mikrofon selbst trifft, Rückkopplungserscheinungen auftreten können, die zu Pfeif- oder Brummtönen in den Lautsprechern oder zu Sprechverzerrungen führen. Zur Vermeidung solcher störenden Rückkopplungen wurden schon verschiedene Vorschläge gemacht, die darauf beruhen, die Lautstärke zu begrenzen, oder beim Auftreten von Rückkopplungen die Ruckkopplungsfrequenz auszufiltern, oder zu unterdrücken. Diese bekannten Vorrichtungen haben einerseits unerwünschte Nebenwirkungen und führen andererseits nicht zu einer völligen Unterdrückung von Rückkopplungen, so daß sie einer ständigen Bedienung durch sehr erfahrene Bedienungspersonen bedürfen.In loudspeaker systems, 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.
Die Erfindung betrifft ein Verfahren sowie eine Vorrichtung zur Unterdrückung der Rückkopplung in den elektroakustischen Anlagen, in denen Mikrofone in Hörweite von Lautsprechern angeordnet sind.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.
Die der Erfindung zugrunde liegende Aufgabe bestand darin, die Rückkopplungserscheinungen in solchen Anlegen mit anderen, wesentlich vereinfachten Mitteln zu unterdrücken.The object on which the invention was based was to suppress the feedback phenomena in such installations with other, substantially simplified means.
Die Lösung dieser Aufgabe besteht darin, daß die Ausgangssignale des Mikrofons, bzw. der Mikrofone, auf zwei Kanäle gegeben, gegeneinander in der Phase versetzt und die beiden Signale in unterschiedlicher Stärke wieder vereinigt und dem Lautsprecher oder den Lautsprechern als Eingangssignal zugeführt werden. Dabei ergibt sich die günstigste Wirkung, wenn die beiden Signale gegeneinander um 180° versetzt werden.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 °.
Eine Vorrichtung zur Durchführung des obenerwähnten erfindungsgemäßen Verfahrens ist dadurch gekennzeichnet, daß an den Ausgang eines Mikrofons zwei einander perallelgeschaltete Kanäle angeschlossen sind, in dem einen Kanal ein in der Phasenverschiebung einstellbarer Phasenschieber angeordnet ist und beide Kanäle wieder zusammengeschaltet sind unter Einschaltung einer Regelvorrichtung in einen der Kanäle. Bei einer weiteren vorteilhaften Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens ist in beiden Kanälen je ein Operationsverstärker angeordnet und die beiden Operationsverstärker sind so gegeneinander geschaltet, daß die Phasenlagen der Signale in beiden Kanälen einander entgegengesetzt sind.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. In a further advantageous device for carrying out the method according to the invention, 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.
Die Erfindung beruht auf der an sich bekannten Tatsache, daß, wenn zwei Signale gleicher Frequenz gegenphasig aufeinandertreffen, diese Signale sich vollständig oder fast vollständig auslöschen können. Es hat sich nun überraschenderweise gezeigt, daß, wenn daß eine der beiden gegenphasig zusammentreffenden Signale wesentlich schwächer ist als das andere Signal einerseits keine für die Sprachwidergabe störende Auslöschung stattfindet, andererseits aber die Neigung zu Rückkopplungserscheinungen sehr erheblich vermindert ist. Wird das gegenphasige Signal verstärkt, so steigt die Rückkopplungssicherheit sehr stark an, während bei Sprach- oder Gesangssignalen eine Wirkung zu beobachten ist, die der Wirkung eines Hoch- und Tiefpaßfilters entspricht, sich also auf die Spreche oder den Gesang nicht negativ, sondern positiv auswirkt. Nur bei einer zu starken Hinzufügung des Anteils des zweiten, gegenphasigen Signals treten hörbare Auslöschungen ein. Eine derart starke Hinzufügung des gegenphesigen Signals ist aber nicht erforderlich, um eine ausreichende Rückkopplungs- sicherheit zu erzielen. Das zweite, gegenphasige Signal kann vielmehr, um Rückkopplungssicherheit zu erzielen, in solcher Stärke zugemischt werden, daß keine Beeinträchtigung der Sprach- oder Gesangswidergabe eintritt.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.
Der Begriff "Lautsprecheranlage" ist sehr allgemein zu verstehen. Er umfaßt z.B. auch Hörgeräte. In diesen können bekanntlich ebenfalls unter ungünstigen Bedingungen Rückkopplungen zwischen Eingengsmikrofon und Lautsprecher (Hörer) auftreten, die in vorteilhafter Weise durch die vorliegende Erfindung beseitigt werden.The term "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.
Im folgenden werden Ausführungsbeispiele des Gegenstandes der Erfindung anhand der Zeichnungen näher erläutert.
- Fig. 1 zeigt in einer Prinzipdarstellung eine erste Ausführungsform einer Vorrichtung nach der Erfindung;
- Fig. 2 zeigt in einem Schaltbild eine weitere Ausführungsform der Vorrichtung nach der Erfindung.
- 1 shows a basic illustration of a first embodiment of a device according to the invention;
- Fig. 2 shows a circuit diagram of a further embodiment of the device according to the invention.
Bei der Vorrichtung nach Fig. 1 wird ein von einem Mikrofon 1 ausgehendes Sprachsignal am Punkt 2 in zwei Kanäle 3 und 4 geteilt. In dem Kanal 4 befindet sich ein Phasenschieber 5, der so eingestellt werden kann, daß die Phase um 180° verdreht wird, so daß die Phase im Kanal 4 der Phase im Kanal 3 entgegengesetzt ist. Ferner befindet sich im Kanal 4 noch eine Regelvorrichtung 6, durch die es möglich ist, das Signal im Kanal 4 wesentlich schwächer zu machen als das im Kanal 3 übertragene Signal. Am Punkt 7 werden die beiden Kanäle 3 und 4 wieder vereinigt und die Signale werden über einen nicht dargestellten Verstärker einem Lautsprecher 8 zugeführt. Das Zusatzsignal im Kanal 4 kann mittels der Regelvorrichtung 6 so eingestellt werden, daß es wesentlich schwächer ist als das im Kanal 3 übertragene Signal und doch ausreicht, um Rückkopplungen zu verhindern.In the device according to FIG. 1, a speech signal originating from a microphone 1 is split into two at point 2
In Fig. 2 ist eine Vorrichtung dargestellt, bei der die von einem nicht dargestellten Mikrofon kommenden Sprach-oder Eingangssignale über einen die Schaltung symmetrierenden Eingengsüberträger Tri mit den Eingängen e1, e2 und e3 den Eingängen E1 und E2 der Schaltung zugeführt werden. Bei bereits symmetrischen Systemen kann der Eingangsübertrager Tr1 auch entfallen. Das Signal wird, wie bereits anhand von Fig. 1 erläutert, wieder in zwei Kanäle aufgeteilt, die in Fig. 2 mit 3' und 4' bezeichnet sind und die, wie ohne weiteres ersichtlich, völlig symmetrisch aufgebaut sind. Im ersten Kanal 3' befindet sich ein Operationsverstärker V1 in der üblichen Schaltungsweise mit Widerständen R11, R12, R13, R14 und R15. Im zweiten Kanal 4' befindet sich ebenfalls ein Operationsverstärker V2 in der üblichen Schaltung mit Widerständen R21, R22, R23, R24 und R25. Der Unterschied zwischen den beiden Kanälen 3' und 4' besteht darin, daß die beiden Operationsverstärker V1 und V2 derart gegeneinander geschaltet sind, daß die Ausgangs- signale der Operationsverstärker V1 und V2 in der Phase einander entgegengesetzt sind. In dem das gegenphasige Signal führenden Kanal 4' ist eine Regelvorrichtung R10 angeordnet, so daß das an der Ausgangsklemme A2 der Schaltung anstehende Signal, das in der Phase dem an der Ausgangsklemme A1 anstehenden Signal entgegengesetzt ist, durch die Regelvorrichtung R10 gegenüber dem Signal an der Ausgangsklemme A1 erheblich geschwächt werden kann. Durch Mischung der beiden Signale wird die Rückkopplungsneigung unterdrückt.2 shows a device in which the voice or input signals coming from a microphone (not shown) are fed to the inputs E1 and E2 of the circuit via an input transmitter Tri which symmetrizes the circuit and has the inputs e1, e2 and e3. In the case of already symmetrical systems, the input transformer Tr1 can also be omitted. As already explained with reference to FIG. 1, 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. In the first channel 3 'there is an operational amplifier V1 in the usual switching mode with resistors R11, R12, R13, R14 and R15. In 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.
Das entstehende Ausgangssignal wird zu seiner Symmetrierung über einen AusgangsObertrager Tr2 mit den Ausgangsklemmen al, a2 und a3 abgenommen. Falls eine Symmetrierung des Ausgangssignals nicht erforderlich ist, kann dieser Ausgangsübertrager Tr2 auch entfallen.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.
Die Eingangsklemme el des Eingengsübertragers Tr1 ist mit der Ausgangsklemme a1 des Ausgangsübertragers Tr2 über eine Abschirmung S verbunden.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.
Bei Lautsprecheranlagen sind häufig mehrere Mikrofone vorhanden, deren Signale am Mischpult gemischt und den Lautsprechern, die meist auch mehrfach vorhanden sind, zugeführt werden. Je nach der Art der zu übertragenden Sprach- oder Gesangssignale kann entweder jedem Mikrofon eine Vorrichtung nach der Erfindung nachgeschaltet werden, worauf dann erst die Signale der verschiedenen Mikrofone gemischt werden, oder es können die Signale von den Mikrofonen zuerst im Mischpult zusammengemischt werden und dann zur Unterdrückung von Rückkopplungen eine Vorrichtung nach der Erfindung in die Ausgangsleitung des Mischpultes eingeschaltet werden. Der erste Weg hat den Vorteil, daß die Rückkopplungsneigung bei den verschiedenen Mikrofonen verschieden groß sein kann, so daß hier die Möglichkeit gegeben ist, für jedes Mikrofon die Vorrichtung so einzustellen, daß Rückkopplungen vermieden werden, ohne daß das Tonsignal beeinträchtigt wird. Dabei ist auch von Bedeutung, daß verschiedene musikalische Darbietungen gegen die durch die Vorrichtung nach der Erfindung eventuell auftretende Auswirkung auf die Tonqualität sehr verschieden empfindlich sind, so daß es möglich ist, für die verschiedenen Mikrofone, je nachdem ob sie Sprache, Geseng oder Instrumentelmusik übertragen, das gegenphasige Signal in unterschiedlicher Stärke zuzumischen.In the case of loudspeaker systems, there are often several microphones, the signals of which are mixed on the mixer and fed to the loudspeakers, which are usually also present several times. Depending on the type of voice or vocal signals to be transmitted, either 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.
Claims (7)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3526591 | 1985-07-25 | ||
| DE19853526591 DE3526591A1 (en) | 1985-07-25 | 1985-07-25 | METHOD FOR SUPPRESSING THE FEEDBACK IN ELECTRO-ACOUSTIC SYSTEMS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0209894A2 true EP0209894A2 (en) | 1987-01-28 |
| EP0209894A3 EP0209894A3 (en) | 1988-01-13 |
Family
ID=6276718
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP86110117A Withdrawn EP0209894A3 (en) | 1985-07-25 | 1986-07-23 | Method for suppressing feedback in electroacoustic installations and arrangement for carrying out this method |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0209894A3 (en) |
| JP (1) | JPS6271396A (en) |
| DE (1) | DE3526591A1 (en) |
| DK (1) | DK352886A (en) |
| ES (1) | ES2000559A6 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2630611A1 (en) * | 1988-04-22 | 1989-10-27 | Bistagne Isabelle | Methods and devices for precluding whistling due to sustained oscillations in an electro-acoustic loop |
| US4879749A (en) * | 1986-06-26 | 1989-11-07 | Audimax, Inc. | Host controller for programmable digital hearing aid system |
| WO1990005436A1 (en) * | 1988-11-10 | 1990-05-17 | Nicolet Instrument Corporation | 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 |
| EP0613319A1 (en) * | 1993-02-23 | 1994-08-31 | France Telecom | Multimicrophone sound pick-up device and associated signal processing device |
| 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 (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DK159357C (en) * | 1988-03-18 | 1991-03-04 | Oticon As | HEARING EQUIPMENT, NECESSARY FOR EQUIPMENT |
| DE102010044917B4 (en) | 2010-09-09 | 2015-01-08 | Iav Gmbh Ingenieurgesellschaft Auto Und Verkehr | Method for avoiding acoustic feedback |
Citations (2)
| 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 |
| US4064462A (en) * | 1976-12-29 | 1977-12-20 | Dukane Corporation | Acoustic feedback peak elimination unit |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| HU169185B (en) * | 1974-06-05 | 1976-10-28 | ||
| HU172630B (en) * | 1976-09-14 | 1978-11-28 | Elektroakusztikai Gyar | Sound system with small excitability |
| DE2738339A1 (en) * | 1977-08-25 | 1979-03-01 | Bosch Gmbh Robert | Amplifier for hearing aid - has shift register delay line to reduce feedback between microphone and loudspeaker |
| DE2807452A1 (en) * | 1978-02-22 | 1979-08-23 | Uwe Zink | Feedback disabling circuit between microphone and amplifier - contains two shift registers each with gain-controlled preamplifier to produce phase shift |
-
1985
- 1985-07-25 DE DE19853526591 patent/DE3526591A1/en not_active Withdrawn
-
1986
- 1986-07-23 EP EP86110117A patent/EP0209894A3/en not_active Withdrawn
- 1986-07-24 ES ES8600584A patent/ES2000559A6/en not_active Expired
- 1986-07-24 DK DK352886A patent/DK352886A/en not_active Application Discontinuation
- 1986-07-25 JP JP17396786A patent/JPS6271396A/en active Pending
Patent Citations (2)
| 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 |
| US4064462A (en) * | 1976-12-29 | 1977-12-20 | Dukane Corporation | Acoustic feedback peak elimination unit |
Cited By (11)
| 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 (en) * | 1988-04-22 | 1989-10-27 | Bistagne Isabelle | Methods and devices for precluding whistling due to sustained oscillations in an electro-acoustic loop |
| WO1990005436A1 (en) * | 1988-11-10 | 1990-05-17 | Nicolet Instrument Corporation | Feedback suppression in digital signal processing hearing aids |
| 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 (en) * | 1993-02-23 | 1994-08-31 | France Telecom | Multimicrophone sound pick-up device and associated signal processing device |
| FR2702118A1 (en) * | 1993-02-23 | 1994-09-02 | Le Tourneur Gregoire | Multisensor device for sound pickup and associated signal processing. |
| 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 |
|---|---|
| JPS6271396A (en) | 1987-04-02 |
| EP0209894A3 (en) | 1988-01-13 |
| DE3526591A1 (en) | 1987-01-29 |
| DK352886A (en) | 1987-01-26 |
| ES2000559A6 (en) | 1988-03-01 |
| DK352886D0 (en) | 1986-07-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| DE2716039C2 (en) | Signal processing circuit for processing two-channel stereophonic audio signals | |
| DE3618586A1 (en) | BASS REFLEX SPEAKER SYSTEM | |
| DE2512907A1 (en) | METHOD AND EQUIPMENT FOR INCREASING THE DIRECTIONAL INFORMATION CONTENT OF SIGNALS | |
| DE3231108A1 (en) | VOICE TRANSFER DEVICE WITH LINE-RECEIVER CONDITIONING CIRCUIT | |
| DE69533211T2 (en) | Signal combination circuit for stereophonic reproduction with cross signal coupling | |
| DE3146560A1 (en) | METHOD FOR CONVERTING ELECTRICAL TONE FREQUENCY SIGNALS TO ACOUSTIC OUTPUT SIGNALS AND ACOUSTIC CONVERTER SYSTEM | |
| DE2436724C2 (en) | Amplifier output circuit | |
| DE2624568A1 (en) | STEREOPHONIC PLAYBACK DEVICE | |
| DE102005033646A1 (en) | Vacuum tube power amplifier switchable between push-pull and single-ended configurations | |
| DE2830451A1 (en) | HEADPHONE | |
| DE60225345T2 (en) | MODULAR SPEAKER | |
| DE3907275C2 (en) | Sound system | |
| EP0209894A2 (en) | Method for suppressing feedback in electroacoustic installations and arrangement for carrying out this method | |
| DE1261559B (en) | Transmitter device for transmitting amplitude-modulated vibrations | |
| DE10242700B4 (en) | Feedback compensator in an acoustic amplification system, hearing aid, method for feedback compensation and application of the method in a hearing aid | |
| DE3036417A1 (en) | Input circuit for hearing-aid amplifier - has changeover switch short-circuiting either microphone or induction coil | |
| DE3708650A1 (en) | METHOD AND CIRCUIT FOR IMPROVING THE HIGH FREQUENCY REPRODUCTION OF A BASS AMPLIFIER | |
| DE2640324A1 (en) | Telephone terminal with loudspeaker output - has two microphones whose outputs are subtracted to eliminate background noise | |
| DE3247844A1 (en) | SPEAKER SYSTEM | |
| DE102005036538A1 (en) | Device and method for controlling a loudspeaker | |
| DE815356C (en) | Intercom | |
| DE2141141A1 (en) | CIRCUIT ARRANGEMENT FOR COUPLING OF A SPEAKER | |
| DE3137747C2 (en) | ||
| DE2316939B2 (en) | Electric hearing aid circuit | |
| DE1487227A1 (en) | Two-channel amplifier for electro-acoustic systems |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AT BE CH DE FR GB IT LI NL |
|
| PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
| AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): AT BE CH DE FR GB IT LI NL |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
| 18D | Application deemed to be withdrawn |
Effective date: 19880714 |