GB2172769A - Ear defender - Google Patents

Ear defender Download PDF

Info

Publication number
GB2172769A
GB2172769A GB08507445A GB8507445A GB2172769A GB 2172769 A GB2172769 A GB 2172769A GB 08507445 A GB08507445 A GB 08507445A GB 8507445 A GB8507445 A GB 8507445A GB 2172769 A GB2172769 A GB 2172769A
Authority
GB
United Kingdom
Prior art keywords
noise
loudspeaker
ear
microphone
channel
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
GB08507445A
Other versions
GB8507445D0 (en
GB2172769B (en
Inventor
Martin John Saxon
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.)
Topexpress Ltd
Original Assignee
Topexpress 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 Topexpress Ltd filed Critical Topexpress Ltd
Priority to GB08507445A priority Critical patent/GB2172769B/en
Publication of GB8507445D0 publication Critical patent/GB8507445D0/en
Publication of GB2172769A publication Critical patent/GB2172769A/en
Application granted granted Critical
Publication of GB2172769B publication Critical patent/GB2172769B/en
Expired legal-status Critical Current

Links

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
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F11/00—Methods or devices for treatment of the ears or hearing sense; Non-electric hearing aids; Methods or devices for enabling ear patients to achieve auditory perception through physiological senses other than hearing sense; Protective devices for the ears, carried on the body or in the hand
    • A61F11/06—Protective devices for the ears
    • A61F11/14—Protective devices for the ears external, e.g. earcaps or earmuffs
    • A61F11/145—Protective devices for the ears external, e.g. earcaps or earmuffs electric, e.g. for active noise reduction
    • 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
    • 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
    • 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
    • G10K11/17873—General system configurations using a reference signal without an error signal, e.g. pure feedforward
    • 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
    • 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
    • G10K2210/3011—Single acoustic input
    • 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
    • G10K2210/321—Physical
    • G10K2210/3222—Manual tuning

Landscapes

  • Acoustics & Sound (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Audiology, Speech & Language Pathology (AREA)
  • Otolaryngology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Vascular Medicine (AREA)
  • Animal Behavior & Ethology (AREA)
  • Biomedical Technology (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Psychology (AREA)
  • Biophysics (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Headphones And Earphones (AREA)
  • Circuit For Audible Band Transducer (AREA)

Abstract

An ear defending device comprises a micro-phone 10 located upstream of a loudspeaker 12, relative to the direction of approach of unwanted intrusive noise, in an assembly adapted to be mounted at a site of entry of said noise into the ear chamber. The output of the microphone is amplified and fed to the downstream loudspeaker to produce noise which tends to cancel the unwanted intrusive noise. An active filter 26 is used to adjust the phase of the cancellation signal. A signal mixing stage 38 allows a communication channel 40 to be added to introduce wanted sounds. <IMAGE>

Description

SPECIFICATION Improvements in acoustic attenuation Field of the invention This invention relates to a method of and device for effecting acoustic attenuation, more especifically the attenuation of unwanted noise entering an acoustic chamber, where the term chamber is intended to embrace, more especially but not exclusively, the human ear chamber incorporating the auditory canal.
Background of the invention The attenuation of broadband noise at the ear has traditionally been achieved by the use of "passive" ear defenders. Such ear defenders generally comprise a rigid cup lined with acoustically absorbent material, the cup being edged with a cushion which is commonly fluid filled. In use the cup is fitted to the ear so that the cushion seals to the head around the ear, whereby the ear is enclosed in a substantially airtight cavity lined with the acoustically absorbent material.
More recently, "active" ear defending apparatus has been proposed to enhance or even partly replace the passive ear defended. In this appraratus a microphone and a loudspeaker, ie acousto-electric input transducer and electroacoustic output transducer, are introduced into the cavity around the ear created by the above-describing cup, the microphone being positioned between the loudspeaker and the entrance to the ear chamber. The loudspeaker is driven by signals derived from the microphone through a feedback control circuit, in such a way that broadband noise received by the microphone, and hence perceived by the ear, is minimised.
Object of the invention Both the passive ear defenders and active ear defending apparatus above described give rise to the disadvantage of totally enclosing the ear in a manner which can be uncomfortable in a hot environment and cosmetically unacceptable in certain (generally non-industrial) situations. Moreover, the active ear defending apparatus is not effective where the sound to be suppressed contains sharp or sudden noises involving high amplitude transients. It is an object of this invention to provide a method of active ear defence and a device for carrying out said method which avoids the disadvantages of the known arrangements.
The invention According to one aspect of the invention, there is provided an ear defending device which comprises a microphone located upstream of a loudspeaker, relative to the direction of approach of unwanted intrusive noise, in an assembly adapted to be mounted at a site of entry of said noise into an acoustic chamber such as the ear chamber, and amplifier means for producing from the output of the microphone an electrical signal which is fed to the downstream loudspeaker to produce noise which tends to cancel the unwanted intrusive noise.
According to another aspect of the invention, there is provided a method of ear defence against unwanted intrusive noise, according to which, at the site of entry of the noise into an acoustic chamber such as the ear chamber, a microphone is located upstream relative to a loudspeaker in the direction of approach of the noise, and the output of the microphone is amplified and fed to the loudspeaker in order to produce noise which tends to cancel the unwanted intrusive noise.
Effectively, in accordance with the invention, a cancellation signal is developed from the microphone outputs during a response time which is equivalent to the time taken for the intrusive noise to progress downstream to the loudspeaker. The amplifier means may incorporate circuitry, such as an active filter, which enables the phase of the cancellation signal to be set or adjusted for maximised noise cancellation.
A preferred amplifier means thus comprises a two channel circuit wherein one channel incorporates an active filter and the other channel incorporates an operational amplifier, these components being followed, in the respective channels, by complementary variable gain amplifiers. The outputs of the two channels are combined and preferably fed to an output to the loudspeaker via a variable gain amplifier.
Between the latter and the loudspeaker, a summing circuit may be provided to which a communications channel is connected, thereby to provide for generation of wanted sound at the loudspeaker. This particularly applies, for example, when the device of the invention is incorporated in an earphone or earpiece set.
The complementary variable gain amplifiers preferably provide a gain of 1- a in the operational amplifier channel and a gain of a in the filter channel, a being adjustable by ganged adjustment of the two said variable gain amplifiers. The active filter has Laplace transfer function chosen to maximise the effect of the cancellation signal. In a typical case, noise attentuation of 9 to 10 dBs is possible without use of a filter, whilst a suitably selected filter can increase the attenuation by about 50%.
The assembly of the invention can be made very small, so as to fit inside the ear at the entrance to the auditory canal, and this assembly may be attached by means of a headband. The use of a cup sealed to the head, which is often undesirable, is thereby avoided.
Description of the drawings A practical arrangment of acoustic attenuator, in accordance with the invention, will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 illustrates a noise attenuating device attached to the ear; and Figure 2 is a circuit diagram of a preferred amplifier means.
Description of embodiment Referring to Fig. 1, the device in accordance with the invention comprises a microphone 10 mounted to an earphone 12 incorporating a loudspeaker. The microphone 10 is disposed on the outside of the earphone 12 relative to the auditory canal 14 within the ear 16 at which the device is attached by means of a headband (not shown). Thus, the microphone is located upstream of the loudspeaker with respect to the direction of entry of unwanted intrusive noise into the ear.
Amplifier processing circuitry 19, shown in Fig. 2, connects to the microphone and earphone via a twin head connecting cable 18.
The amplifier processing circuitry of Fig. 2 has an input 20 from the microphone 10. This input feeds a filter channel 22 and an operational amplifier channel 24. The channel 22 comprises an active filter 26 with selected Laplace transfer function, followed by a variable gain amplifier 28. The other channel comprises operational amplifier 30 followed by variable gain amplifier 32. The two variable gain amplifiers 28 and 32 are complementary, developing gains of a and 1 -a, respectively.
These two amplifiers 28 and 32 are also ganged for user adjustment of a.
The two channels are combined at circuit 34, the summed signal being fed through a user adjustable variable gain amplifier 36 to a summing circuit 38 whereat a signal on a communication channel 40 may be introduced.
The output 42 from the summing circuit 38 is fed to the earphone 12.
The amplifier processing circuitry provides for user adjustment of phase and amplification to enable a preferred cancellation signal to be developed at the output 42, thereby to enable maximum unwanted noise cancellation at the earphone.
The above-described device in accordance with the invention is embodied as an earpiece attachment, for example for wearing in a tractor cab or for the reduction of ambient noise during use of a personal stereo headset or the like. However, in some circumstances, the device, or more than one such device, may be employed in the wall or walls of an acoustic chamber having a site or sites of entry of unwanted intrusive noise which is required to be attenuated or suppressed.

Claims (11)

1. An ear defending device comprises (a) micro-phone means located upstream (relative to the direction of approach of unwanted intrusive noise), of a loudspeakerin (c) an assembly adapted to be mounted at a site of entry of noise into the auditory canal and (d) amplifier means for producing from the output of the microphone an electrical signal which upon being fed to the downstream loudspeaker produces noise which tends to cancel the unwanted intrusive noise.
2. A device as claimed in claim 1, wherein a cancellation signal is developed from the microphone output after a response time which is equivalent to the time taken for the intrusive noise to progress downstream to the loudspeaker.
3. A device as claimed in claim 1 or 2, wherein the amplifier means incorporates circuit means which enables the phase of the cancellation signal to be adjusted to maximised noise cancellation.
4. A device as claimed in claim 3, wherein the said circuit means is an active filter.
5. A device as claimed in claim 1 or 2, wherein the amplifier means comprises a two channel circuit wherein one channel incorporates an active filter and the other channel incorporates an operational amplifier, these components being followed, in the respective channels, by complementary variable gain amplifiers, and the outputs of the two channels are combined and fed as an output signal to the loudspeaker via a variable gain amplifier.
6. A device as claimed in claim 5, wherein a summing circuit is provided between the variable gain amplifier and the loudspeaker to which a communication channel is connected, thereby to provide for generation of wanted sound at the loudspeaker.
7. A device as claimed in claim 6, wherein the complementary variable gain amplifiers provide a gain of (1~a) in the operational amplifier channel and a gain of (a) in the filter channel, (a being adjustable by ganged adjustment of the two said variable gain amplifiers).
8. A device as claimed in any of claims 1 to 7, wherein the microphone, loudspeaker and filter and amplifiers are packaged in one assembly which is adapted to fit inside the ear at the entrance to the auditory canal.
9. A device as claimed in claim 8, wherein the assembly is adapted to be attached by means of a headband.
10. A method of ear defence against unwanted intrusive noise in which, at the site of entry of noise into the auditory canal, a microphone is located upstream relative to a loudspeaker in the direction of approach of the noise, and the output of the microphone is amplified and fed to the loudspeaker in a manner to produce noise which tends to cancel the unwanted intrusive noise.
11. An ear defending device constructed, arranged and adapted to operate substantially as herein described by way of example with reference to the accompanying drawings.
GB08507445A 1985-03-21 1985-03-21 Improvements in acoustic attenuation Expired GB2172769B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08507445A GB2172769B (en) 1985-03-21 1985-03-21 Improvements in acoustic attenuation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08507445A GB2172769B (en) 1985-03-21 1985-03-21 Improvements in acoustic attenuation

Publications (3)

Publication Number Publication Date
GB8507445D0 GB8507445D0 (en) 1985-05-01
GB2172769A true GB2172769A (en) 1986-09-24
GB2172769B GB2172769B (en) 1988-07-06

Family

ID=10576437

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08507445A Expired GB2172769B (en) 1985-03-21 1985-03-21 Improvements in acoustic attenuation

Country Status (1)

Country Link
GB (1) GB2172769B (en)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989000746A1 (en) * 1987-07-20 1989-01-26 Plessey Overseas Limited Improvements relating to noise reduction systems
US4953217A (en) * 1987-07-20 1990-08-28 Plessey Overseas Limited Noise reduction system
EP0390386A2 (en) * 1989-03-25 1990-10-03 Sony Corporation Noise reducing device
US5001763A (en) * 1989-08-10 1991-03-19 Mnc Inc. Electroacoustic device for hearing needs including noise cancellation
EP0423172A1 (en) * 1988-06-24 1991-04-24 Sensor Electronics Inc Active noise reduction system.
US5251263A (en) * 1992-05-22 1993-10-05 Andrea Electronics Corporation Adaptive noise cancellation and speech enhancement system and apparatus therefor
EP0581565A2 (en) * 1992-07-28 1994-02-02 Nelson Industries, Inc. Active acoustic attenuation system with power limiting
EP0596623A2 (en) * 1992-11-02 1994-05-11 AT&T Corp. Electronic cancellation of ambient noise in telephone receivers
EP0680738A1 (en) * 1994-05-04 1995-11-08 Hauni Maschinenbau Aktiengesellschaft Auditory protection system on a production machine
US5524058A (en) * 1994-01-12 1996-06-04 Mnc, Inc. Apparatus for performing noise cancellation in telephonic devices and headwear
US5740258A (en) * 1995-06-05 1998-04-14 Mcnc Active noise supressors and methods for use in the ear canal
EP0870298A2 (en) * 1995-06-07 1998-10-14 Andrea Electronics Corporation Noise cancellation and noise reduction apparatus
US6683965B1 (en) 1995-10-20 2004-01-27 Bose Corporation In-the-ear noise reduction headphones
GB2436657A (en) * 2006-04-01 2007-10-03 Sonaptic Ltd Ambient noise-reduction system
WO2008090342A3 (en) * 2007-01-25 2008-10-30 Wolfson Microelectronics Plc Ambient noise reduction

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6363345B1 (en) 1999-02-18 2002-03-26 Andrea Electronics Corporation System, method and apparatus for cancelling noise
US6594367B1 (en) 1999-10-25 2003-07-15 Andrea Electronics Corporation Super directional beamforming design and implementation

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1492963A (en) * 1974-02-22 1977-11-23 Lawson Tancred H Preventing or reducing transmission of sound
GB1530814A (en) * 1977-06-20 1978-11-01 British Aircraft Corp Ltd Hearing protection devices
GB1555760A (en) * 1976-09-27 1979-11-14 Chaplin G B B Active methods for attenuating compression waves
GB2097629A (en) * 1981-04-15 1982-11-03 Nat Res Dev Methods and apparatus for active sound control
GB2160742A (en) * 1984-06-21 1985-12-24 Nat Res Dev Damping for directional sound cancellation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1492963A (en) * 1974-02-22 1977-11-23 Lawson Tancred H Preventing or reducing transmission of sound
GB1555760A (en) * 1976-09-27 1979-11-14 Chaplin G B B Active methods for attenuating compression waves
GB1530814A (en) * 1977-06-20 1978-11-01 British Aircraft Corp Ltd Hearing protection devices
GB2097629A (en) * 1981-04-15 1982-11-03 Nat Res Dev Methods and apparatus for active sound control
GB2160742A (en) * 1984-06-21 1985-12-24 Nat Res Dev Damping for directional sound cancellation

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989000746A1 (en) * 1987-07-20 1989-01-26 Plessey Overseas Limited Improvements relating to noise reduction systems
US4953217A (en) * 1987-07-20 1990-08-28 Plessey Overseas Limited Noise reduction system
AU608041B2 (en) * 1987-07-20 1991-03-21 Bae Systems (Defence Systems) Limited Improvements relating to noise reduction systems
EP0423172A1 (en) * 1988-06-24 1991-04-24 Sensor Electronics Inc Active noise reduction system.
EP0423172A4 (en) * 1988-06-24 1991-09-11 Sensor Electronics, Inc. Active noise reduction system
EP0390386A2 (en) * 1989-03-25 1990-10-03 Sony Corporation Noise reducing device
EP0390386A3 (en) * 1989-03-25 1991-10-23 Sony Corporation Noise reducing device
US5138664A (en) * 1989-03-25 1992-08-11 Sony Corporation Noise reducing device
US5001763A (en) * 1989-08-10 1991-03-19 Mnc Inc. Electroacoustic device for hearing needs including noise cancellation
US5251263A (en) * 1992-05-22 1993-10-05 Andrea Electronics Corporation Adaptive noise cancellation and speech enhancement system and apparatus therefor
EP0581565A2 (en) * 1992-07-28 1994-02-02 Nelson Industries, Inc. Active acoustic attenuation system with power limiting
EP0581565A3 (en) * 1992-07-28 1994-10-12 Nelson Ind Inc Active acoustic attenuation system with power limiting.
EP0596623A2 (en) * 1992-11-02 1994-05-11 AT&T Corp. Electronic cancellation of ambient noise in telephone receivers
EP0596623A3 (en) * 1992-11-02 1997-01-02 At & T Corp Electronic cancellation of ambient noise in telephone receivers.
US5524058A (en) * 1994-01-12 1996-06-04 Mnc, Inc. Apparatus for performing noise cancellation in telephonic devices and headwear
EP0680738A1 (en) * 1994-05-04 1995-11-08 Hauni Maschinenbau Aktiengesellschaft Auditory protection system on a production machine
US5740258A (en) * 1995-06-05 1998-04-14 Mcnc Active noise supressors and methods for use in the ear canal
EP0870298A2 (en) * 1995-06-07 1998-10-14 Andrea Electronics Corporation Noise cancellation and noise reduction apparatus
EP0870298A4 (en) * 1995-06-07 1999-12-22 Andrea Electronics Corp Noise cancellation and noise reduction apparatus
US6683965B1 (en) 1995-10-20 2004-01-27 Bose Corporation In-the-ear noise reduction headphones
GB2436657A (en) * 2006-04-01 2007-10-03 Sonaptic Ltd Ambient noise-reduction system
GB2436657B (en) * 2006-04-01 2011-10-26 Sonaptic Ltd Ambient noise-reduction control system
WO2008090342A3 (en) * 2007-01-25 2008-10-30 Wolfson Microelectronics Plc Ambient noise reduction

Also Published As

Publication number Publication date
GB8507445D0 (en) 1985-05-01
GB2172769B (en) 1988-07-06

Similar Documents

Publication Publication Date Title
US5740258A (en) Active noise supressors and methods for use in the ear canal
US5001763A (en) Electroacoustic device for hearing needs including noise cancellation
US5033090A (en) Hearing aid, especially of the in-the-ear type
US6801629B2 (en) Protective hearing devices with multi-band automatic amplitude control and active noise attenuation
JP2989843B2 (en) Active noise reduction system
GB2172769A (en) Ear defender
US7043037B2 (en) Hearing aid having acoustical feedback protection
US5276740A (en) Earphone device
US5208867A (en) Voice transmission system and method for high ambient noise conditions
US8295503B2 (en) Noise reduction device and method thereof
US5815582A (en) Active plus selective headset
US5452361A (en) Reduced VLF overload susceptibility active noise cancellation headset
CA2022888A1 (en) Electroacoustic device for hearing needs including noise cancellation
US10424287B2 (en) Active noise-control device
CA2076390C (en) Noise reducing system
CN109565626B (en) Acoustic open type earphone with active noise reduction function
US20110206214A1 (en) Active noise reduction system
JPS63503186A (en) Method and device for attenuating extrinsic noise reaching the eardrum and improving the intelligibility of electroacoustic communications
US6714654B2 (en) Hearing aid operative to cancel sounds propagating through the hearing aid case
JP6495448B2 (en) Self-voice blockage reduction in headset
JP2022016340A (en) Earpiece, hearing device and system for active occlusion cancellation
EP0643881B1 (en) Active plus selective headset
JP3112268B2 (en) Noise reduction device
WO1991011078A1 (en) Earphone device
JPH067397A (en) Soundproof ear cover

Legal Events

Date Code Title Description
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
PE20 Patent expired after termination of 20 years

Effective date: 20050320