EP0195641B1 - Dispositifs de réduction de bruit - Google Patents

Dispositifs de réduction de bruit Download PDF

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Publication number
EP0195641B1
EP0195641B1 EP86301946A EP86301946A EP0195641B1 EP 0195641 B1 EP0195641 B1 EP 0195641B1 EP 86301946 A EP86301946 A EP 86301946A EP 86301946 A EP86301946 A EP 86301946A EP 0195641 B1 EP0195641 B1 EP 0195641B1
Authority
EP
European Patent Office
Prior art keywords
noise
noise reduction
microphones
microphone
gain control
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.)
Expired - Lifetime
Application number
EP86301946A
Other languages
German (de)
English (en)
Other versions
EP0195641A2 (fr
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
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 Siemens Plessey Electronic Systems Ltd filed Critical Siemens Plessey Electronic Systems Ltd
Priority to AT86301946T priority Critical patent/ATE91189T1/de
Publication of EP0195641A2 publication Critical patent/EP0195641A2/fr
Publication of EP0195641A3 publication Critical patent/EP0195641A3/en
Application granted granted Critical
Publication of EP0195641B1 publication Critical patent/EP0195641B1/fr
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

  • the invention relates to arrangements for reducing the level of acoustic noise field within the internal cavities or enclosures of so-called ear-defenders or earphone structures when being worn by personnel (for example, pilots, vehicle drivers, industrial workers) in high noise environments.
  • 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 term 'ambient noise' refers to noise, due to external sources, present within the cavity of an ear-defender.
  • ANR acoustic noise reduction
  • the acoustic noise reduction arrangements will, at certain frequencies, be feeding inphase (that is, positive feedback) signals rather than anti-phase (that is, negative feedback) signals to the noise-cancelling transducers.
  • inphase that is, positive feedback
  • anti-phase that is, negative feedback
  • 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.
  • Fixed loop gain control techniques could be used were it not for changes that would be likely to occur in the characteristics of the components of the ANR system with the passage of time. However, such fixed loop gain techniques would not provide the requisite compensation for changes in sensitivity of the noise-cancelling transducers resulting from changes in the volume of the earphone structure cavities which occur when the earphone structures are worn by different persons or from small changes in earphone structure position likely to be caused by normal movements of the wearer's head.
  • 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.
  • Changes in the microphone output can result from a change in loop gain (for example, due to earphone movement) which requires the automatic gain control arrangement to act to adjust the gain and it can also result from a change in external noise spectrum/level.
  • 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, the automatic gain control may provide a gain which continuously oscillates about the requisite value.
  • An aim of the present invention is to provide a noise reduction arrangement having means for automatically adjusting the loop gain in response to the level of measured noise detected.
  • an earphone active noise reduction arrangement comprising an earphone structure, first and second microphones and an automatic gain control circuit arranged to provide a variable loop gain dependent upon a variable noise reduction which is produced in operation by the active noise reduction arrangement, characterised in that said first and second microphones are located, respectively within front and rear internal cavities of said earphone structure, the said front cavity being open for contact with the wearer's head and the said rear cavity being a closed space within the earphone structure, the microphones being positioned on the opposite sides of a noise-cancelling transducer diaphragm extending between said cavities, in which the first microphone detects the noise level within the front cavity and produces an output signal which is amplified by a variable gain amplifier and inverted before being applied to the noise-cancelling transducer, and in which the second microphone detects the noise level within the rear cavity and produces an output signal which together with the output signal from the first microphone is processed in the automatic gain control circuit for the generation of a gain control signal which is applied to the variable gain
  • the automatic gain control circuit comprises an adder circuit arranged to receive signals dependent upon the output signals from the first and second microphones, a first converter for providing a DC signal dependent upon the output signal from the first microphone, a second converter for providing a DC signal dependent upon the output signal from the adder circuit, and a comparator circuit, for comparing signals dependent upon the DC signals provided by the first and second converters, arranged to provide, in dependence upon this comparison, a gain control signal for controlling the gain of the noise reduction arrangement.
  • 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.
  • the earphone structure 1 embodies a small noise pick-up microphone 5 which detects the volume of 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 closed rear cavity 12.
  • the provision of means dividing the earphone structure into two separate cavities allows the earphone to produce high levels of low frequency sound.
  • 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 has occurred.
  • 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 closed 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 microphone 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-canceling 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 output 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 that the 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)
  • Circuit For Audible Band Transducer (AREA)
  • Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
  • Glass Compositions (AREA)
  • Inorganic Insulating Materials (AREA)
  • Maintenance And Management Of Digital Transmission (AREA)
  • Vehicle Interior And Exterior Ornaments, Soundproofing, And Insulation (AREA)
  • Headphones And Earphones (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)

Claims (4)

  1. Ensemble de réduction active de bruit à écouteur, comprenant une structure à écouteur, un premier (5) et un second (13) microphone et un circuit (14-20) de réglage automatique de gain destiné à donner un gain variable de boucle qui dépend de la réduction variable du bruit qui est produit pendant le fonctionnement par l'ensemble de réduction active de bruit, caractérisé en ce que le premier et le second microphone (5, 13) sont disposés respectivement dans les cavités internes avant et arrière (11, 12) de la structure (1) à écouteur, la cavité avant (11) débouchant afin qu'elle soit au contact de la tête (3) de la personne qui porte l'ensemble et la cavité arrière (12) étant un espace fermé à l'intérieur de la structure à écouteur, les microphones étant disposés de part et d'autre d'un diaphragme à transducteur (9) de compensation de bruit disposé entre les cavités, dans lequel le premier microphone (5) détecte le niveau de bruit dans la cavité avant (11) et produit un signal de sortie qui est amplifié par un amplificateur (6) à gain variable et inversé (7) avant d'être appliqué au transducteur (8) de compensation de bruit, et dans lequel le second microphone (13) détecte le niveau de bruit dans la cavité arrière (12) et forme un signal de sortie qui, avec le signal de sortie du premier microphone (5), est traité dans le circuit (14-20) de réglage automatique de gain afin qu'il crée un signal de réglage de gain qui est appliqué à l'amplificateur (6) à gain variable et qui assure le maintien constant d'un niveau de réduction du bruit mesuré.
  2. Ensemble de réduction de bruit selon la revendication 1, dans lequel le circuit de réglage automatique de gain comprend un circuit additionneur (16) destiné à recevoir les signaux en fonction des signaux de sortie du premier et du second microphone (5, 13), un premier convertisseur (18) destiné à donner un signal en courant continu qui dépend du signal de sortie du premier microphone (5), un second convertisseur (17) destiné à transmettre un signal en courant continu qui dépend du signal de sortie du circuit additionneur (16), et un circuit comparateur (20) destiné à comparer les signaux qui dépendent des signaux en courant continu donnés par le premier et le second convertisseur (18, 17), et à transmettre, en fonction de cette comparaison, un signal de réglage du gain de l'ensemble de réduction de bruit.
  3. Ensemble de réduction de bruit selon la revendication 1 ou 2, comprenant en outre un filtre (14, 15) destiné à filtrer les signaux de sortie des microphones (5, 13).
  4. Ensemble de réduction de bruit selon l'une quelconque des revendications 1 à 3, comprenant en outre, entre le circuit comparateur (20) et le premier convertisseur (18), un amplificateur (19) destiné à amplifier le signal reçu par le circuit comparateur (20) en provenance du premier convertisseur (18).
EP86301946A 1985-03-16 1986-03-17 Dispositifs de réduction de bruit Expired - Lifetime EP0195641B1 (fr)

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 EP0195641A2 (fr) 1986-09-24
EP0195641A3 EP0195641A3 (en) 1988-10-05
EP0195641B1 true EP0195641B1 (fr) 1993-06-30

Family

ID=10576109

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86301946A Expired - Lifetime EP0195641B1 (fr) 1985-03-16 1986-03-17 Dispositifs de réduction de bruit

Country Status (4)

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

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8391530B2 (en) 2009-01-16 2013-03-05 Sennheiser Electronic Gmbh & Co. Kg Helmet and apparatus for active noise suppression
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
US8929082B2 (en) 2010-05-17 2015-01-06 Thales Avionics, Inc. Airline passenger seat modular user interface device
US9487295B2 (en) 2010-11-15 2016-11-08 William James Sim Vehicle media distribution system using optical transmitters
US9654854B2 (en) 2011-06-01 2017-05-16 Paul Darlington In-ear device incorporating active noise reduction
US9818394B2 (en) 2009-11-30 2017-11-14 Graeme Colin Fuller Realisation of controller transfer function for active noise cancellation

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4736431A (en) * 1986-10-23 1988-04-05 Nelson Industries, Inc. Active attenuation system with increased dynamic range
US5181252A (en) * 1987-12-28 1993-01-19 Bose Corporation High compliance headphone driving
EP0333411A3 (fr) * 1988-03-16 1991-07-31 University Of Essex Assemblages d'écouteur
CA2023142A1 (fr) * 1989-08-23 1991-02-24 Roman Sapiejewski Dispositif d'attaque pour casque d'ecoute a diaphragme a grande elasticite
JP5709760B2 (ja) 2008-12-18 2015-04-30 コーニンクレッカ フィリップス エヌ ヴェ オーディオノイズキャンセリング
US10034086B2 (en) 2013-03-26 2018-07-24 Bose Corporation Headset porting
EP3419307B1 (fr) * 2017-06-19 2020-05-13 Audio-Technica Corporation Casque d'écoute
EP3664466B1 (fr) 2018-12-07 2022-03-30 GN Audio A/S Écouteur avec microphone de rétroaction active de suppression du bruit disposé sur le côté arrière d'un diaphragme de haut-parleur

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4473906A (en) * 1980-12-05 1984-09-25 Lord Corporation Active acoustic attenuator
DE3133107A1 (de) * 1981-08-21 1983-03-10 Michael 5440 Mayen Hofmann Persoenlicher schallschutz

Cited By (7)

* 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
US8391530B2 (en) 2009-01-16 2013-03-05 Sennheiser Electronic Gmbh & Co. Kg Helmet and apparatus for active noise suppression
US9818394B2 (en) 2009-11-30 2017-11-14 Graeme Colin Fuller Realisation of controller transfer function for active noise cancellation
US8929082B2 (en) 2010-05-17 2015-01-06 Thales Avionics, Inc. Airline passenger seat modular user interface device
US9487295B2 (en) 2010-11-15 2016-11-08 William James Sim Vehicle media distribution system using optical transmitters
US9654854B2 (en) 2011-06-01 2017-05-16 Paul Darlington In-ear device incorporating active noise reduction

Also Published As

Publication number Publication date
GB8506860D0 (en) 1985-04-17
ATE91189T1 (de) 1993-07-15
DE3688624D1 (de) 1993-08-05
EP0195641A2 (fr) 1986-09-24
EP0195641A3 (en) 1988-10-05
DE3688624T2 (de) 1993-10-07

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