EP0195641A2 - Anordnungen zur Begrenzung von Störungen - Google Patents

Anordnungen zur Begrenzung von Störungen Download PDF

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Publication number
EP0195641A2
EP0195641A2 EP86301946A EP86301946A EP0195641A2 EP 0195641 A2 EP0195641 A2 EP 0195641A2 EP 86301946 A EP86301946 A EP 86301946A EP 86301946 A EP86301946 A EP 86301946A EP 0195641 A2 EP0195641 A2 EP 0195641A2
Authority
EP
European Patent Office
Prior art keywords
noise reduction
noise
signal
microphones
dependent
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.)
Granted
Application number
EP86301946A
Other languages
English (en)
French (fr)
Other versions
EP0195641B1 (de
EP0195641A3 (en
Inventor
Robert Christopher Twiney
Anthony John Salloway
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems Defence Systems Ltd
Original Assignee
Plessey Overseas Ltd
Siemens Plessey Electronic Systems Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Plessey Overseas Ltd, Siemens Plessey Electronic Systems Ltd filed Critical Plessey Overseas Ltd
Priority to AT86301946T priority Critical patent/ATE91189T1/de
Publication of EP0195641A2 publication Critical patent/EP0195641A2/de
Publication of EP0195641A3 publication Critical patent/EP0195641A3/en
Application granted granted Critical
Publication of EP0195641B1 publication Critical patent/EP0195641B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1787—General system configurations
    • G10K11/17879—General system configurations using both a reference signal and an error signal
    • G10K11/17881—General system configurations using both a reference signal and an error signal the reference signal being an acoustic signal, e.g. recorded with a microphone
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1781—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
    • G10K11/17821—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the input signals only
    • G10K11/17823—Reference signals, e.g. ambient acoustic environment
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1781—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
    • G10K11/17821—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the input signals only
    • G10K11/17825—Error signals
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17857—Geometric disposition, e.g. placement of microphones
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/108—Communication systems, e.g. where useful sound is kept and noise is cancelled
    • G10K2210/1081—Earphones, e.g. for telephones, ear protectors or headsets
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3013—Analogue, i.e. using analogue computers or circuits
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3028—Filtering, e.g. Kalman filters or special analogue or digital filters
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3045—Multiple acoustic inputs, single acoustic output
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3056—Variable gain
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3213—Automatic gain control [AGC]

Definitions

  • This invention relates to arrangements for reducing the level of acoustic noise fields within the internal cavities or enclosures of so-called ear-defenders or earphone structures when being worn by personnel (e.g. pilots, vehicle drivers, industrial workers etc.) in high noise environments.
  • personnel e.g. pilots, vehicle drivers, industrial workers etc.
  • Known active noise reduction (ANR) arrangements for reducing the aforesaid acoustic noise field in ear-defenders comprise small noise pick-up microphones and noise-cancelling transducers mounted within the internal cavities or enclosures of the respective ear-defenders.
  • the noise pick-up microphones produce electrical signal outputs in response to the acoustic noise fields within the aforesaid cavities and these signal outputs are phase inverted, filtered and amplified in a feedback loop arrangement for the production of noise-cancelling signals fed to the noise-cancelling transducers which accordingly produce noise-cancelling acoustic signals of substantially the same amplitude but of opposite phase to the acoustic noise field waveforms.
  • the noise pick-up microphones do not detect the incoming or ambient noise level but rather the reduced noise level within the cavities following acoustic noise reduction (ANR). It can be shown that such ANR arrangements produce a reduction in noise at a particular frequency given by:- where G is the total gain of the feedback loop arrangement and: is the total loop phase change at the particular frequency boncerned. From this expression it can readily be appreciated that the scale of noise reduction achieved is highly dependent upon the total loop gain. Due to the imperfect transfer functions of the noise pick-up microphones and noise-cancelling tranducers the acoustic noise reduction arrangements will, at certain frequencies, be feeding in-phase (i.e. positive feedback) signals rather than anti-phase (i.e.
  • the overall loop gain of the system must be kept at less than unity at the frequencies concerned otherwise the noise levels in the cavities of the earphone structures will actually be increased rather than reduced by the positive feedback signals fed to the noise- cancelling transducers.
  • the loop gain must be kept below unity at the aforesaid frequencies in order to maintain stability the loop gain of the ANR must be sufficiently high to provide the optimum acoustic noise reduction.
  • Automatic loop gain control techniques would be capable of providing the requisite aforesaid compensation but the conventional procedure has hitherto been to utilise the output signal from the noise pick-up microphone of the ANR arrangement for automatic gain control purposes.
  • the pick-up microphone only senses the reduced noise within the earphone structure cavities not the ambient noise level.
  • Changes in the microphone output can result from a change in loop gain (e.g. due to earphone movement) which requires the automatic gain control arrangement to act to adjust the gain and from a change in external noise spectrum/level in which case the automatic gain control arrangement is not required to act.
  • loop gain e.g. due to earphone movement
  • the automatic gain control arrangement to act to adjust the gain and from a change in external noise spectrum/level in which case the automatic gain control arrangement is not required to act.
  • the cause of these changes in loop gain cannot be distinguished in an active noise reduction system utilising noise pick-up microphone outputs only for gain control purposes. Consequently such simple linear feedback gain control systems are inherently unstable continuously oscillating the loop gain about the requisite value.
  • an active noise reduction arrangement of the general form hereinbefore described which includes an automatic gain control arrangement providing a variable loop gain dependant upon the variable noise reduction which is produced by the active noise reduction arrangement and which is effectively measured by noise pick-up microphones located, respectively, in earphone structure front and rear internal cavities positioned in front of and at the rear of a noise-cancelling transducer diaphragm and producing a signal related to the measured noise reduction.
  • the active noise reduction arrangement illustrated comprises a generally cup-shaped circumaural earphone structure 1 arranged to enclose the wearer's ear 2.
  • the rim of the structure 1 is cushioned against the side of the wearer's head 3 by means of a compliant ring cushion 4. 1
  • the earphone structure 1 embodies a small noise pick-up microphone 5 which detects the noise within the earphone adjacent the wearer's ear 2 and provides an electrical output dependent upon the detected noise.
  • This output signal from the microphone is amplified by an amplifier 6 and the amplified signal is then inverted and filtered by a phase inverter/filter 7 before being applied to a noise-cancelling transducer 8.
  • This transducer 8 includes a movable diaphragm 9 attached to an opening in a rigid wall structure 10. The diaphragm 9 and wall 10 divide the interior of the earphone structure 1 into a front cavity 11 containing the noise pick-up microphone 5 and a rear cavity 12.
  • the back pressure from the rear of the transducer diaphragm 9 is contained in the earphone rear cavity 12 and prevented from mixing with the front cavity pressure.
  • the noise level is coherent in both earphone cavities 11 and 12.
  • the noise-cancelling signals applied to the transducer 8 cause vibration of the diaphragm 9 and generation of acoustic signals of the same amplitude but of opposite phase to the noise signals picked up by the microphone 5.
  • the noise pick-up microphone 5 only detects the noise level within the earphone cavity 11 after noise reduction. It does not detect ambient noise.
  • the depicted arrangement according to the invention includes a further noise pick-up microphone 13 identical to the microphone 5, the microphone 13 being located within the rear cavity 12 of the earphone structure 1.
  • the noise in both of the earphone cavities 11 and 12 will share the same amplitude and phase at low frequencies since the earphone is substantially transparent to low frequency sounds. Movement of the transducer diaphragm 9 towards the front cavity 11 will increase the front cavity pressure but decrease the pressure in the rear cavity 12. Consequently, the sound produced in the rear cavity 12 by the transducer diaphragm will be 180° out of phase with that produced in the front cavity 11. Accordingly, the microphone 5 senses ambient noise plus anti-phase noise while the microphone 13 senses ambient noise minus anti-phase noise. The consequential noise-representative output signals derived from the microphones 5 and 13 are applied to respective band-pass filters 14 and 15 which provide output in the low frequency range (typically 300-400 Hz).
  • noise-cancelling signals fed to the transducer 8 will be 180° out of phase with the noise sensed by the microphone 5 located in cavity 11.
  • the outputs from the filters 14 and 15 are applied to a signal adder 16 which will provide an output signal related solely to the ambient noise level, the anti-phase noise-reducing components sensed by the microphones 5 and 13 being mutually cancelling by the process of addition.
  • the output signal from the adder 16 and the output signal from the filter 14 are converted to DC levels by respective root mean square voltage to DC converters 17 and 18 with the signal derived from the microphone 5 being given a predetermined value of gain by an amplifier 19 in order to correspond with the required level of noise reduction.
  • the outputs from the converters 17 and 18 (after amplification by amplifier 19) are fed into a voltage comparator 20 which compares the DC levels of the outputs and accordingly generates a gain control signal which is fed to the amplifier 6, the control signal having a value which ensures thatthe measured noise reduction of the arrangement is kept constant.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Headphones And Earphones (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Vehicle Interior And Exterior Ornaments, Soundproofing, And Insulation (AREA)
  • Maintenance And Management Of Digital Transmission (AREA)
  • Glass Compositions (AREA)
  • Inorganic Insulating Materials (AREA)
EP86301946A 1985-03-16 1986-03-17 Anordnungen zur Begrenzung von Störungen Expired - Lifetime EP0195641B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86301946T ATE91189T1 (de) 1985-03-16 1986-03-17 Anordnungen zur begrenzung von stoerungen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB858506860A GB8506860D0 (en) 1985-03-16 1985-03-16 Noise reduction arrangements
GB8506860 1985-03-16

Publications (3)

Publication Number Publication Date
EP0195641A2 true EP0195641A2 (de) 1986-09-24
EP0195641A3 EP0195641A3 (en) 1988-10-05
EP0195641B1 EP0195641B1 (de) 1993-06-30

Family

ID=10576109

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86301946A Expired - Lifetime EP0195641B1 (de) 1985-03-16 1986-03-17 Anordnungen zur Begrenzung von Störungen

Country Status (4)

Country Link
EP (1) EP0195641B1 (de)
AT (1) ATE91189T1 (de)
DE (1) DE3688624T2 (de)
GB (1) GB8506860D0 (de)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0265097A2 (de) * 1986-10-23 1988-04-27 Nelson Industries, Inc. Aktives Dämpfungsgerät mit erhöhter dynamischer Aktivität
EP0333411A2 (de) * 1988-03-16 1989-09-20 University Of Essex Kopfhöreranordnung
EP0414479A2 (de) * 1989-08-23 1991-02-27 Bose Corporation Hochkomplianter Kopfhörertreiber
US5181252A (en) * 1987-12-28 1993-01-19 Bose Corporation High compliance headphone driving
WO2010070561A1 (en) * 2008-12-18 2010-06-24 Koninklijke Philips Electronics N.V. Active audio noise cancelling
US8929082B2 (en) 2010-05-17 2015-01-06 Thales Avionics, Inc. Airline passenger seat modular user interface device
US10034086B2 (en) 2013-03-26 2018-07-24 Bose Corporation Headset porting
JP2019004456A (ja) * 2017-06-19 2019-01-10 株式会社オーディオテクニカ ヘッドホン
EP3664466A1 (de) * 2018-12-07 2020-06-10 GN Audio A/S Ohrhörer mit rückkopplungsmikrofon zur aktiven rauschunterdrückung, das an der rückseite einer lautsprechermembran angeordnet ist, und verfahren zur herstellung solch eines ohrhörers

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8571227B2 (en) 2005-11-11 2013-10-29 Phitek Systems Limited Noise cancellation earphone
US8666085B2 (en) 2007-10-02 2014-03-04 Phitek Systems Limited Component for noise reducing earphone
DE102009005302B4 (de) 2009-01-16 2022-01-05 Sennheiser Electronic Gmbh & Co. Kg Schutzhelm und Vorrichtung zur aktiven Störschallunterdrückung
US9818394B2 (en) 2009-11-30 2017-11-14 Graeme Colin Fuller Realisation of controller transfer function for active noise cancellation
EP2471710A1 (de) 2010-11-15 2012-07-04 Nigel Greig Medienverteilungssystem
JP2014533444A (ja) 2011-06-01 2014-12-11 フィテック システムズ リミテッドＰｈｉｔｅｋ Ｓｙｓｔｅｍｓ Ｌｉｍｉｔｅｄ 能動騒音低減を組み込むインイヤー型装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2088951A (en) * 1980-12-05 1982-06-16 Lord Corp Acoustic attenuators with active sound cancelling
DE3133107A1 (de) * 1981-08-21 1983-03-10 Michael 5440 Mayen Hofmann Persoenlicher schallschutz

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2088951A (en) * 1980-12-05 1982-06-16 Lord Corp Acoustic attenuators with active sound cancelling
DE3133107A1 (de) * 1981-08-21 1983-03-10 Michael 5440 Mayen Hofmann Persoenlicher schallschutz

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0265097A2 (de) * 1986-10-23 1988-04-27 Nelson Industries, Inc. Aktives Dämpfungsgerät mit erhöhter dynamischer Aktivität
EP0265097A3 (en) * 1986-10-23 1989-02-08 Nelson Industries, Inc. Active attenuation system with increased dynamic activity
US5181252A (en) * 1987-12-28 1993-01-19 Bose Corporation High compliance headphone driving
EP0333411A2 (de) * 1988-03-16 1989-09-20 University Of Essex Kopfhöreranordnung
EP0333411A3 (de) * 1988-03-16 1991-07-31 University Of Essex Kopfhöreranordnung
EP0414479A2 (de) * 1989-08-23 1991-02-27 Bose Corporation Hochkomplianter Kopfhörertreiber
EP0414479A3 (en) * 1989-08-23 1991-11-06 Bose Corporation High compliance headphone driving
CN102257560A (zh) * 2008-12-18 2011-11-23 皇家飞利浦电子股份有限公司 有源音频噪声消除
WO2010070561A1 (en) * 2008-12-18 2010-06-24 Koninklijke Philips Electronics N.V. Active audio noise cancelling
CN102257560B (zh) * 2008-12-18 2013-11-20 皇家飞利浦电子股份有限公司 有源音频噪声消除
US8948410B2 (en) 2008-12-18 2015-02-03 Koninklijke Philips N.V. Active audio noise cancelling
US8929082B2 (en) 2010-05-17 2015-01-06 Thales Avionics, Inc. Airline passenger seat modular user interface device
US10034086B2 (en) 2013-03-26 2018-07-24 Bose Corporation Headset porting
JP2019004456A (ja) * 2017-06-19 2019-01-10 株式会社オーディオテクニカ ヘッドホン
EP3664466A1 (de) * 2018-12-07 2020-06-10 GN Audio A/S Ohrhörer mit rückkopplungsmikrofon zur aktiven rauschunterdrückung, das an der rückseite einer lautsprechermembran angeordnet ist, und verfahren zur herstellung solch eines ohrhörers
CN111294708A (zh) * 2018-12-07 2020-06-16 Gn 奥迪欧有限公司 具有布置在扬声器膜片后侧的anc反馈麦克风的耳机
US10878798B2 (en) 2018-12-07 2020-12-29 Gn Audio A/S Earphone with an active noise cancelling feedback microphone arranged at the rear-side of a speaker diaphragm
CN111294708B (zh) * 2018-12-07 2022-09-09 Gn 奥迪欧有限公司 具有布置在扬声器膜片后侧的anc反馈麦克风的耳机

Also Published As

Publication number Publication date
GB8506860D0 (en) 1985-04-17
ATE91189T1 (de) 1993-07-15
DE3688624T2 (de) 1993-10-07
EP0195641B1 (de) 1993-06-30
DE3688624D1 (de) 1993-08-05
EP0195641A3 (en) 1988-10-05

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