EP0327617B1 - Ameliorations relatives a des systemes de reduction de bruit - Google Patents

Ameliorations relatives a des systemes de reduction de bruit Download PDF

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Publication number
EP0327617B1
EP0327617B1 EP88905991A EP88905991A EP0327617B1 EP 0327617 B1 EP0327617 B1 EP 0327617B1 EP 88905991 A EP88905991 A EP 88905991A EP 88905991 A EP88905991 A EP 88905991A EP 0327617 B1 EP0327617 B1 EP 0327617B1
Authority
EP
European Patent Office
Prior art keywords
filter
filter means
high pass
loop
microphone
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
EP88905991A
Other languages
German (de)
English (en)
Other versions
EP0327617A1 (fr
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
Priority claimed from GB878717043A external-priority patent/GB8717043D0/en
Priority claimed from GB878717042A external-priority patent/GB8717042D0/en
Priority claimed from GB878717040A external-priority patent/GB8717040D0/en
Application filed by Siemens Plessey Electronic Systems Ltd filed Critical Siemens Plessey Electronic Systems Ltd
Priority to AT88905991T priority Critical patent/ATE82083T1/de
Publication of EP0327617A1 publication Critical patent/EP0327617A1/fr
Application granted granted Critical
Publication of EP0327617B1 publication Critical patent/EP0327617B1/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
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17853—Methods, e.g. algorithms; Devices of the filter
    • 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
    • G10K11/1787—General system configurations
    • G10K11/17875—General system configurations using an error signal without a reference signal, e.g. pure feedback
    • 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
    • G10K11/17885—General system configurations additionally using a desired external signal, e.g. pass-through audio such as music or speech
    • 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
    • G10K2210/3028—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
    • G10K2210/3039—Nonlinear, e.g. clipping, numerical truncation, thresholding or variable input and output 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
    • G10K2210/301—Computational
    • G10K2210/3045—Multiple acoustic inputs, single acoustic output

Definitions

  • This invention relates to systems for reducing the level of acoustic noise fields within ear-defenders or earphone structures worn by personnel (e.g., pilots, vehicle drivers, military personnel) in high noise environments.
  • personnel e.g., pilots, vehicle drivers, military personnel
  • noise pick-up microphones and noise-cancelling sound generators (usually known as loudspeakers) 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 cavities and these signal outputs are phase inverted, filtered and amplified in a feedback loop and fed to the noise-cancelling sound generators which produce noise-cancelling acoustic signals of substantially the same amplitude but of opposite phase to the acoustic noise field waveforms.
  • a further problem which occurs is that due to the imperfect transfer functions of both the microphone and generator, the total bandwidth for feedback signals having an appropriate phase is limited, being bounded by regions in which positive feedback occurs. It is usual to employ in feedback systems in general a lowpass first order filter operating at a high frequency in order to stabilize the loop. However such first order low pass filters are not appropriate for filtering out sound energy frequencies in ANR systems because of the large phase changes which occur in the cut-off regions which give rise to problems of positive feedback and signal enhancement.
  • an active noise reduction system comprising a noise-cancelling sound generator, a microphone acoustically coupled to said generator, a feedback loop connected between said microphone and said generator, and including loop stabilisation means for inverting the phase of microphone signals and filtering the microphone signals, means for amplifying the phase inverted and filtered signals, and a first high pass frequency filter means for filtering out sound energy from high pressure sound pulses arising from low frequency buffets, characterised in that the first filter means has a gain characteristic which is relatively low in a first frequency band and then rises continuously to a relatively high value in a second frequency band, said first filter means introducing a phase shift which rises to a maximum value in a transitional region of said gain characteristic of said first high pass frequency filter means, said system further comprising a second high pass filter means coupled between the loop stabilising means and the amplifying means for increasing loop gain and/or adjusting phase shift by predetermined amounts within one or more predetermined frequency bands, wherein the second filter means has a gain characteristic which
  • this aspect of the invention is based on the recognition that the major part of sound energy in high pressure pulses is present at low frequencies say below 100 Hz and thus the provision of low frequency filter means in the feedback loop can reduce a major part of the sound energy in the pulses.
  • filter means is conveniently referred to as an anti-buffet filter (ABF).
  • ABSF anti-buffet filter
  • the filter means referred to above may be used in conjunction with a voltage limiting means, which prevents the generator from being overdriven by amplification of high pressure sound pulses.
  • a voltage limiting means may comprise a non-linear amplifier or zener diode arrangement.
  • second filter means increasing gain or adjusting phase shift, preferably both, prevents enhancement of the signal in the feedback loop arising from imperfect transfer functions of the microphone and generator.
  • the further filter means is conveniently termed an anti-enhancement filter (AEF).
  • AEF anti-enhancement filter
  • This further aspect of the invention is based on our discovery that enhancement problems caused by transducer imperfections arise in a frequency region centred at about 500 Hz where the gain decreases whereas the phase lag in this area increases to about 3 ⁇ /2.
  • a high pass filter which adjusts the gain in this region whilst providing a phase advance compensating phase shift can significantly reduce the problems of signal enhancement.
  • the preferred speech signals are injected at a single point in the feedback loop between the AEF and the amplifying means, in order that the speech signals are substantially uncoloured by the AEF and other filters. It will be understood that the speech signals are in a frequency range which is for the most part above the frequency range in which the ANR is operative and the speech signals are not therefore reduced. They may however be affected by higher frequency filters in the feedback loop.
  • the active noise reduction system 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 noise within the earphone adjacent to the wearer's ear 2 and provides an electrical output dependent upon the detected noise.
  • This output signal from the microphone is passed through an anti-buffet filter 6, a loop stabilisation unit 7,a low-pass filter 8, an anti-enhancement filter 10 and amplifier 12, to a noise cancelling sound generator (loudspeaker) 14 which is mounted on a baffle 16 within structure 1.
  • Loop stabilisation unit 7 includes a phase inverter 72, a loop stabilizing filter 74 (which may be incorporated in low-pass filter 8 as in Figure 6) for filtering out very high frequencies, and a voltage limiting circuit 76 comprising a zener diode switching arrangement for limiting high amplitude input signals.
  • Filter 6 is placed first in the feedback loop in order to minimise signal values in the loop.
  • the effect of the anti-enhancement filter is to reduce noise effects arising from imperfect transfer functions of microphone 5 and generator 14.
  • a speech signal is injected between anti-enhancement filter 10 and amplifier 12 at an input node 18.
  • the introduction of the speech signal at this point allows the speech signal to be substantially uncoloured by the loop filters.
  • the speech signals may be pre-emphasised by amplification where they may be attenuated by the ANR system.
  • the ABF 6 comprises an amplifier 20 having a negative feedback loop with a resistor R1 connected to its inverting input, which receives an input signal from a resistive/capacitive network R2, R3, C1.
  • the non-inverting input of the amplifier is connected through a resistor R4 to ground.
  • ABF 6 The characteristics of ABF 6 are shown in Figure 3, whence it may be seen that the filter has a loss factor of about 8db up to about 100 Hz at which frequency the loss reduces continuously until at about 500Hz the filter exhibits a small gain factor.
  • the phase shift introduced by the filter is an advance with increasing frequency rising in the transitional region from the base level of substantially 180° (the filter includes an inverting amplifier) to a maximum at about 200 Hz of about 215°. This phase shift must be taken into account when considering the overall loop stability.
  • the effect of the ABF 6 on the overall feedback loop transfer function is to attenuate the low frequency end of the function whereby noise in the frequency range up to 200Hz is severely attenuated.
  • AEF The preferred form of AEF is shown in Figure 4 as comprising two cascaded stages 21, 22, each stage comprising an amplifier 24 with a resistor R1 in a negative feedback loop and with the inverting amplifier input being connected to ground via the series combination of a resistor R2 and capacitor C1.
  • the filter characteristics are shown in Figure 5 with the gain having step-form, being roughly 0db up to 100 Hz and then rising to 10db gain at 1 kHz.
  • the phase shift, a phase advance with increasing frequency rises in the region in which the gain changes, from a base level of substantially 0° a maximum value of 25° at roughly 500 Hz.
  • the gain reduces to a minimum value at about 500 Hz whereas the phase shift in this area rises to a maximum of about more than 3 ⁇ /2.
  • the transfer functions are modified in this area to reduce phase shift and increase gain, thereby reducing signal enhancement.
  • a circuit diagram of low pass filter 8 is shown in Figure 6 as comprising a transitional second order filter including an amplifier 60 having a non-inverting input connected to a filter input via resistors R1, R2 and a capacitor C1 coupled between the amplifier input and ground.
  • Two feedback loops are provided from the amplifier output to the non-inverting input: a first loop including a capacitor C2 and a second loop comprising resistors R3, R4, R5 and a capacitor C3 in series with a resistor R9 connected between resistors R4, R5 and ground.
  • a further feedback loop is provided comprising a resistor R7 connected between the amplifier output and the inverting amplifier input.
  • a further resistor R8 is connected between resistor R7 and ground.
  • the characteristics of the filter are shown in Figure 7 where the gain is close to 0db up to about 1000Hz and is about -30db around 10,000Hz. The gain decreases between these regions relatively quickly in a cut-off region.
  • the phase shift across the filter is roughly 150°, (the filter includes a non-inverting amplifier) in the region below 1,000Hz and above 10,000Hz, but decreases to a minimum, (a phase lag with increasing frequency) of about 45° in the centre of the cut-off region.
  • a phase change of roughly 105° is acceptable and is much smaller than 180 degrees resulting from a conventional second order low-pass filter.
  • a second order filter is shown, the filter could be a higher or lower order if desired.
  • a high pass filter which combines the functions of the AEF and ABF and is herein referred to as an ABEF.
  • the filter is a second order filter comprising two filter sections connected in cascade, the filter sections being identical. (If desired a first order filter could be employed).
  • Each filter section comprises an input port 80 coupled to the inverting input of an amplifier 82 through a resistance R1 connected in parallel with a capacitance C1 and a resistance R2.
  • the non-inverting input of the amplifier is connected to ground via a resistance R3, and the output of the amplifier 86 is connected in a negative feedback loop to the inverting input of the amplifier via a resistor R4.
  • the gain is slightly greater than 0db up to about 500 Hz and then rises to about 10db at a frequency of 2 kHz in a transitional region between 500Hz-2kHz.
  • the phase shift changes from a constant level of about 0° to a maximum value of substantially 60° at about 1 kHz.
  • the filters shown may be replaced by digital filters, and the elements of the feedback loop may be digitised by employing a micro-computer with appropriate routines.
  • the invention claimed is intended to cover both analog and digital systems.

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  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Audiology, Speech & Language Pathology (AREA)
  • General Health & Medical Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Electroluminescent Light Sources (AREA)
  • Gas-Filled Discharge Tubes (AREA)
  • Exhaust Silencers (AREA)
  • Noise Elimination (AREA)
  • Networks Using Active Elements (AREA)

Claims (9)

  1. Système de réduction active de bruit, comprenant un générateur sonore (14) de compensation de bruit, un microphone (5) couplé de manière acoustique au générateur (14), une boucle de rétroaction connectée entre le microphone (5) et le générateur (14) et comprenant un dispositif (7) de stabilisation de boucle destiné à inverser la phase des signaux du microphone et à filtrer les signaux du microphone, un dispositif (12) destiné à amplifier les signaux ayant subi l'inversion de phase et le filtrage, et un premier filtre passe-haut (6) destiné à retirer l'énergie sonore des impulsions sonores à haute pression dues à des souffles à basses fréquences, caractérisé en ce que le premier dispositif de filtrage (6) a une caractéristique de gain qui est relativement faible dans une première bande de fréquences et qui s'élève de façon continue jusqu'à une valeur relativement élevée dans une seconde bande de fréquences, le premier dispositif de filtrage (6) introduisant un déphasage qui s'élève jusqu'à une valeur maximale dans une région de transition de la caractéristique du gain du premier dispositif de filtrage passe-haut, le système comprenant en outre un second dispositif de filtrage passe-haut (10) couplé entre le dispositif (7) de stabilisation de boucle et le dispositif amplificateur (12) afin qu'il augmente le gain de boucle et/ou ajuste le déphasage de quantités prédéterminées dans une ou plusieurs bandes prédéterminées de fréquences, dans lequel le second dispositif de filtrage (10) a une caractéristique de gain qui est relativement faible dans une première bande de fréquences et qui s'élève de façon continue à une valeur relativement élevée dans une seconde bande de fréquences, le déphasage introduit par le second dispositif de filtrage (10) augmentant jusqu'à une valeur maximale dans la région de transition des caractéristiques de gain du filtre.
  2. Système selon la revendication 1, dans lequel le second dispositif de filtrage (10) comprend un ou plusieurs étages, chaque étage comprenant un amplificateur (24) avec une boucle (20, 22) de rétroaction résistive négative, et un trajet résistif et capacitif (R2, C1) relié à un potentiel de référence connecté à l'entrée d'inversion de l'amplificateur.
  3. Système selon la revendication 1 ou 2, dans lequel les fonctions du premier (6) et du second (10) filtre sont assurées par un seul dispositif de filtrage passe-haut, les caractéristiques de transfert étant sélectionnées afin qu'elles retirent par filtrage l'énergie sonore des impulsions sonores à haute pression et augmentent le gain de boucle et/ou ajustent le déphasage pour compenser les caractéristiques de transfert du microphone (5) et du générateur (10).
  4. Système selon l'une quelconque des revendications précédentes, comprenant en outre un dispositif d'injection d'un signal de parole dans la boucle de rétroaction entre le dispositif de filtrage (10) et le dispositif d'amplification (12).
  5. Système selon l'une quelconque des revendications précédentes, dans lequel le second dispositif de filtrage passe-haut (10) comprend un ou plusieurs étages, chaque étage ayant un filtre actif passe-haut du premier ordre, le réseau actif de filtrage étant couplé à l'amplificateur opérationnel afin qu'il donne une caractéristique passe-haut.
  6. Système selon la revendication 5, dans lequel le premier dispositif de filtrage (6) comporte un ou plusieurs étages, chaque étage comprenant un filtre actif passe-haut du premier ordre.
  7. Système selon la revendication 6, dans lequel le premier dispositif (6) de filtrage passe-haut comprend une combinaison résistive et capacitive (R2, R3, C1) et un amplificateur (20) ayant des entrées d'inversion et de non-inversion avec une boucle de rétroaction négative (R1), une entrée du dispositif de filtrage étant placée d'un premier côté de la combinaison résistive et capacitive (R2, R3, C1) et l'autre côté de la combinaison étant connecté à l'entrée d'inversion et l'entrée de non-inversion étant connectée à un potentiel de référence par une connexion résistive (R4).
  8. Système selon l'une quelconque des revendications précédentes, dans lequel un dispositif (7) de stabilisation de boucle comporte un dispositif (76) destiné à limiter l'amplitude des signaux dans la boucle de rétroaction.
  9. Système selon l'une quelconque des revendications précédentes, dans lequel le premier dispositif (6) de filtrage passe-haut est connecté entre le microphone (5) et le dispositif (7) de stabilisation de boucle.
EP88905991A 1987-07-20 1988-07-20 Ameliorations relatives a des systemes de reduction de bruit Expired - Lifetime EP0327617B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88905991T ATE82083T1 (de) 1987-07-20 1988-07-20 Anordnungen zur stoerschall-verminderung.

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
GB8717042 1987-07-20
GB878717043A GB8717043D0 (en) 1987-07-20 1987-07-20 Noise reduction systems
GB878717042A GB8717042D0 (en) 1987-07-20 1987-07-20 Noise reduction systems
GB8717043 1987-07-20
GB8717040 1987-07-20
GB878717040A GB8717040D0 (en) 1987-07-20 1987-07-20 Noise reduction systems

Publications (2)

Publication Number Publication Date
EP0327617A1 EP0327617A1 (fr) 1989-08-16
EP0327617B1 true EP0327617B1 (fr) 1992-11-04

Family

ID=27263515

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88905991A Expired - Lifetime EP0327617B1 (fr) 1987-07-20 1988-07-20 Ameliorations relatives a des systemes de reduction de bruit

Country Status (6)

Country Link
EP (1) EP0327617B1 (fr)
AT (1) ATE82083T1 (fr)
AU (1) AU608041B2 (fr)
CA (1) CA1299725C (fr)
DE (1) DE3875717T2 (fr)
WO (1) WO1989000746A1 (fr)

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5091954A (en) * 1989-03-01 1992-02-25 Sony Corporation Noise reducing receiver device
KR100231219B1 (ko) * 1990-01-19 1999-11-15 오오가 노리오 이어폰 장치
US5276740A (en) * 1990-01-19 1994-01-04 Sony Corporation Earphone device
US5224168A (en) * 1991-05-08 1993-06-29 Sri International Method and apparatus for the active reduction of compression waves
AU6127494A (en) * 1993-01-29 1994-08-15 Active Noise And Vibration Technologies, Inc. Earpiece for active noise cancelling headset
DE69424419T2 (de) * 1993-06-23 2001-01-04 Noise Cancellation Technologies, Inc. Aktive lärmunterdrückungsanordnung mit variabler verstärkung und verbesserter restlärmmessung
AT403417B (de) * 1995-04-25 1998-02-25 Fritz Dr Paschke Schallfiltervorrichtung
US5675658A (en) * 1995-07-27 1997-10-07 Brittain; Thomas Paige Active noise reduction headset
CN1427988A (zh) * 2000-03-07 2003-07-02 新西兰商史莱柏Dsp公司 有源噪声抑制系统
US8054992B2 (en) 2006-04-24 2011-11-08 Bose Corporation High frequency compensating
US8077874B2 (en) 2006-04-24 2011-12-13 Bose Corporation Active noise reduction microphone placing
DE102009005302B4 (de) 2009-01-16 2022-01-05 Sennheiser Electronic Gmbh & Co. Kg Schutzhelm und Vorrichtung zur aktiven Störschallunterdrückung
US8085946B2 (en) 2009-04-28 2011-12-27 Bose Corporation ANR analysis side-chain data support
US8345888B2 (en) * 2009-04-28 2013-01-01 Bose Corporation Digital high frequency phase compensation
US8553900B2 (en) * 2010-05-14 2013-10-08 Creative Technology Ltd Noise reduction circuit with monitoring functionality
US11164554B2 (en) 2020-03-06 2021-11-02 Bose Corporation Wearable active noise reduction (ANR) device having low frequency feedback loop modulation

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4061875A (en) * 1977-02-22 1977-12-06 Stephen Freifeld Audio processor for use in high noise environments
US4654871A (en) * 1981-06-12 1987-03-31 Sound Attenuators Limited Method and apparatus for reducing repetitive noise entering the ear
ZA825676B (en) * 1981-08-11 1983-06-29 Sound Attenuators Ltd Method and apparatus for low frequency active attennuation
DE3133107A1 (de) * 1981-08-21 1983-03-10 Michael 5440 Mayen Hofmann Persoenlicher schallschutz
GB2172769B (en) * 1985-03-21 1988-07-06 Topexpress Ltd Improvements in acoustic attenuation
GB8517716D0 (en) * 1985-07-13 1985-08-21 Plessey Co Plc Noise reduction arrangements

Also Published As

Publication number Publication date
DE3875717T2 (de) 1993-03-18
WO1989000746A1 (fr) 1989-01-26
AU608041B2 (en) 1991-03-21
CA1299725C (fr) 1992-04-28
AU2071688A (en) 1989-02-13
DE3875717D1 (de) 1992-12-10
EP0327617A1 (fr) 1989-08-16
ATE82083T1 (de) 1992-11-15

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