EP0516695A1 - Noise reducing system. - Google Patents
Noise reducing system.Info
- Publication number
- EP0516695A1 EP0516695A1 EP91904859A EP91904859A EP0516695A1 EP 0516695 A1 EP0516695 A1 EP 0516695A1 EP 91904859 A EP91904859 A EP 91904859A EP 91904859 A EP91904859 A EP 91904859A EP 0516695 A1 EP0516695 A1 EP 0516695A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- signal
- control system
- active control
- noise
- region
- 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
Links
- 230000003044 adaptive effect Effects 0.000 claims abstract description 47
- 238000001914 filtration Methods 0.000 claims abstract description 11
- 230000002238 attenuated effect Effects 0.000 claims description 7
- 230000005540 biological transmission Effects 0.000 claims description 5
- 210000005069 ears Anatomy 0.000 claims description 3
- 230000003111 delayed effect Effects 0.000 description 12
- 238000001228 spectrum Methods 0.000 description 6
- 238000004891 communication Methods 0.000 description 4
- 230000000875 corresponding effect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 230000003252 repetitive effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
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
- G10K11/1783—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 handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
- G10K11/17837—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 handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions by retaining part of the ambient acoustic environment, e.g. speech or alarm signals that the user needs to hear
-
- 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
- G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive 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
- G10K11/1787—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
- G10K11/17879—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
- 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
- G10K2210/10—Applications
- G10K2210/121—Rotating machines, e.g. engines, turbines, motors; Periodic or quasi-periodic signals in general
-
- 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
- G10K2210/3018—Correlators, e.g. convolvers or coherence calculators
-
- 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
- G10K2210/50—Miscellaneous
- G10K2210/511—Narrow band, e.g. implementations for single frequency cancellation
Definitions
- This invention relates generally to the selective attenuation of noise where tonal noises are attenuated more than broadband (random) noises. More specifically the tones may be produced by one or more sources of noise each of which generate noise at a fundamental frequency and possibly harmonic frequencies.
- the tones reach a region where they provide a disturbance and reduce the ability of a person to hear other sounds which are generally of a more random nature (eg speech signals) .
- the invention relates to an active noise control system which provides more attenuation of the tonal noises than of the random sounds in the region and does not require a signal link to the source or sources of tonal noise.
- tonal noise includes narrow-band random noise, and noise includes vibration.
- Headsets which selectively cancel the noise produced by a single rotating machine are known (Chaplin - GB2104754), but these require a link, by cable or ultrasonic/infrared transmission, to the source of repetitive noise in order to generate a trigger signal.
- the system requires one link per machine. This link or links can be inconvenient - if they are cable they restrict the movement of the wearer and if they are by transmission they may be unreliable as the wearer moves into regions where the transmission is obscured.
- GB2104754 describes the possibility of using a local microphone to obtain a signal to drive a phase-locked loop to generate a trigger signal but admits that this will only be effective when the repetitive noise is particularly regular. As described his method will not be able to deal with multiple sources of tonal noise.
- an active control system for attenuating tonal noise more than random noise in a region, which does not require a signal link to the source or sources of the tonal noise, comprising
- - transducer means to generate sounds in the region which interfere with the tonal noise to produce at least in part cancellation of the tonal noise and thereby attenuating the tonal noise more than random noise within that region.
- first circuit means for effectively delaying a signal related at least in part to the uncontrolled sound in the region where selective attenuation is required
- an adaptive filter having the effectively delayed signal supplied thereto and adaptive attenuation characteristic is controlled by the second circuit means to produce signals for driving the transducer means
- the operation of the filter is adapted so as to selectively attenuate tonal sounds more than random sounds.
- the processing in the second circuit means may include cross-correlating the effectively delayed signal (or signals derived therefore, or from which the said signals are themselves derived and which may itself be modified by filtering) and the monitor signal (or signals derived therefrom, or from which the said signals are themselves derived and which may itself be modified by filtering) .
- the processing in the second circuit means may include calculating the cross spectrum between the effectively delayed signal (or signals derived therefrom, or from which the said signals are themselves derived and which may itself be modified by filtering) and the monitor signal (or signals derived therefrom, or from which the said signals are themselves derived and which may itself be modified by filtering) .
- the said signal related at least in part to the uncontrolled sound in the region where selective attenuation is required may be obtained from a sensor located close to the region where selective attenuation is required.
- the said signal related at least in part to the uncontrolled sound in the region where selective attenuation is required may be obtained by subtracting the signals which drive the transducer means (or signals derived therefrom, or from which the said signals are themselves derived and which may itself be modified by filtering) from the monitor signal.
- the first circuit means may effectively delay the signal it receives by actually delaying the signal it receives.
- this delay is adjusted, by the first adaption unit means which is itself responsive the the spectrum or auto-correlation of the input to the first circuit means, so that the sum of this delay plus any delay in the transmission process from the transducer to the sensor providing the monitor signal is greater than the correlation time of the noises to be unattenuated and shorter than the correlation time of the noises to be attenuated.
- This means that the system is unable to attenuate noises with short duration cross-correlations (ie broadband random signals) and yet is able to attenuate noises with long duration cross-correlations.
- the first circuit means may include one or more narrow-band filters whose outputs are fed to the adaptive filter. These narrow-band filters can be fixed or tunable so that the centre frequencies can be adjusted to correspond to the frequencies of the tones to be cancelled and their bandwidth adjusted to include these tonal noises.
- the narrow-band filters being adjusted by the first adaption unit means which is itself responsive to the spectrum or auto-correlation of the input to the first circuit means.
- the adaptive filter can include one or more parallel adaptive filter sections each of which has a characteristic at least partly determined by minimising the cross-correlation between its input and the monitor signals.
- the first circuit means includes narrow-band filters the individual filter outputs are fed one to each of the parallel adaptive filter sections of the adaptive filter.
- Each adaptive filter section may be a jth order finite impulse response filter where the coefficients are adjusted with a gradient descent algorithm.
- a separate sensor is used to produce the signal for input to the first circuit means, advantageously that sensor is positioned so that it is insensitive to the noise produced by the transducers or the effect of the transducers on the signal it produces is reduced by electronic subtraction.
- the system may be incorporated in a headset or ear defender. Either one system would be used or alternatively two systems would be used so that the quietened region generally includes one or both ears.
- the sensors providing the monitor signal could be any transducer that can be used to infer the unsteady pressure at a point located close to each ear, for example, a microphone located close to each ear.
- the sensors providing the signal as input to the first circuit means could be one microphone located on or near the top of the headset or alternatively one close to the back of the shell of one or both earpieces, and in the further alternative no sensor is required specifically to generate this signal, the signal being derived from the monitor signal as described herein.
- the transducer may be any device capable of generating unsteady pressure fluctuations, for example a loudspeaker.
- the transducers may be mounted close to the ear so as to influence the unsteady pressure in the region around one or both ears, for example, the transducers may be mounted in the shell of one or both earpieces.
- the headset can be of an open-backed type to allow the easy entry of desirable speech signals.
- the headset may be part of a communications headset where desirable sounds are reproduced through the loudspeakers.
- an effectively delayed and adaptive filter generally of the form described herein may be incorporated in the speech receiving microphone channel in order to attenuate the background tonal noises picked up by the microphone.
- Figure 1 is a block schematic diagram of one embodiment of the invention
- FIG. 2 is a block schematic diagram of an alternative embodiment of the invention.
- Figure 3 is a block schematic diagram of one embodiment of the invention where the sensor signal is derived from a sensor in the region to be controlled.
- Figure 4 is a block schematic diagram of an alternative embodiment of the invention where the sensor signal is derived from a sensor in the region to be controlled.
- Figure 5 shows example autocorrelations for random noise and for tonal noise.
- Figure 6 shows one embodiment of the invention incorporated into a headset.
- Figure 7 shows another embodiment of the invention incorporated into a headset.
- Figure 8 shows a further embodiment.of the invention incorporated into a headset. Detailed description of the preferred embodiments.
- Figure one shows a sensor, 1, which produces a signal representative of the sound in region 2.
- This signal, 3, is delayed in a first circuit means, 4, and the resultant signal fed via an adaptive filter, 5, to a transducer, 6, which generates sound to interfere with the sound in the region 2.
- the coefficients of the adaptive filter, 5, are adjusted by a second circuit means, 26, in accordance with an adaptive algorithm, described below, which uses monitor signal, 7, from a sensor, 8, in the region to be controlled, 2, and the input, 9, to the adaptive filter, 5.
- the first circuit means, 4, is adapted by the first adaption unit means, 10, in accordance with the spectrum or auto-correlation of the signal, 3.
- the delay is adjusted so that it is greater than the correlation time of the sound that is ' to be left unattenuated and yet less than the correlation time of the sound to be attenuated. This delay may be made to depend upon frequency where some frequency selectivity is required.
- the adaptive algorithm of the second circuit means 26 is any adaptive algorithm which adjusts the adaptive filter in order to minimise the correlation between the filter's input and the monitor signal. These may be of the frequency domain type which involve calculating cross-spectra or the time domain type which involve cross-correlating. Many algorithms of this type are described in WIDROW & STEARNS 'adaptive signal processing* . One such time domain algorithm is described below:
- the input signal, 9, is denoted by u(t) and the output of the adaptive filter section, 5, is denoted by y(t) .
- u(t) the output of the adaptive filter section
- y(t) Normally the signals are in sampled digital form having been converted by an analogue to digital converter either before or after the delay unit.
- the sampled version of the input and output are represented as u(k) and y(k) where k represents the time instant.
- the signals will be converted back to analogue form after the adaptive filter, 5.
- the output y(k) is related to the input
- the output of sensor, 8, the monitor signal, is w(k) and this comprises two components v(k) , the uncontrolled noise, and the component due to the transducer, 6.
- b_ ⁇ +1 (i) is the next update of the filter coefficient bj (i) .
- r(k-i) w(k) can be interpretted as a single sample estimate of the cross-correlation between the two sugnals r and w.
- Other aproximations are possible such as
- One particular novel feature of this invention is the ability of the circuit means, 11, to reduce the tonal noise more than the broadband random noise. This feature is now explained.
- the adaptive filter section described above will drive the correlation (for positive time lags) between its input and the monitor signal to zero by adjusting the coefficients of the filter so that a cancelling noise is produced to eliminate any noise which contributes to the correlation between the two. By introducing a delay into the input signal there will no longer be any correlation between the two (for positive time lags) for broadband noises with shorter correlation times than the delay and thus the adaptive filter section will do nothing.
- FIG. 5a shows a typical cross- correlation of the input to the first circuit means and monitor signal when their sensors are close together and receiving broadband noise.
- Figure 5b shows the typical cross-correlation when their sensors are receiving a narrow-band (tonal) sound.
- D shifts the cross- correlation so that the origin is at the point marked D. Since the adaptive filter is only able to control the sounds with a significant level of cross- correlation to the right of the origin only the narrow-band signal will be controlled. If the system receives a combination of many noises it will eliminate all those with a cross-correlation beyond the point D and so it will eliminate all tones.
- the signal, 3, is not contaminated with noises received by its sensor, 1, from the transducer, 6.
- This may be achieved by making the sensor, 1, directional so that it is insensitive to sounds from the transducer, or by positioning it so that it is insensitive, or by providing an additional filter which takes the transducer signal as an input and whose output is used to subtract the effect of the transducer from the sensor signal in a manner similar to that described for eliminating the effect of the transducer produced noise on the monitor signal.
- Figure 2 shows a similar layout to figure 1 but with a different internal layout for the circuit means 11.
- the signal, 3, from the sensor, 1, is fed to one or more narrow-band filters in a first circuit means, 12, whose outputs, 16, are fed one to each of the parallel adaptive filter sections of the adaptive filter, 14.
- the output of all of the parallel sections are combined to form the drive to the transducer, 6.
- the adaption of the individual parallel adaptive filter sections of the adaptive filter, 14, is accomplished by the second circuit means, 15, in response to the monitor signal 7 and each of the narrow-band filter outputs 16.
- the second circuit means uses the adaptive algorithm described above where the coefficients of each of the parallel adaptive filter sections are adapted in accordance with the corresponding input and the monitor signal.
- the narrow-band filters in a first circuit means, 12, are either fixed or tunable. In the case when they are fixed there are a sufficient number of them, closely spaced in frequency, so that a tonal signal of any frequency in the range of interest will pass through one of them.
- this first circuit When a tonal noise is fed to this first circuit means with a bandwidth smaller than the bandwidth of the narrow-band filters there will be an output from one of the filters which is a delayed (and thus phase- shifted) version of the input. Because the cross- correlation of the sensor and monitor signals will have a long correlation time, despite the delay introduced by the filter, this output will have a correlation (for positive time lags) with the monitor signal and thus the corresponding parallel adaptive filter section of the adaptive filter, 14, will be adapted to produce an output signal to attenuate the tonal noise.
- this first circuit When a broadband signal is fed to this first circuit means which has a bandwidth much larger than the bandwidth of the narrow-band filter some output will be generated at each of the filters in the bandwidth of the original signal, but the outputs will be delayed versions of the input (delayed by a time corresponding to the reciprocal of the bandwidth of the narrow-band filters) and because of the short correlation time of the original broadband signal this (effectively) delayed signal will have little cross- correlation with the monitor signal and thus the parallel adaptive filter sections will produce little output and the noise will be unattenuated.
- the narrow-band filters may be tunable in order to minimise the complexity of the system by reducing the number of narrow-band filters.
- the narrow-band filters would be continually adjusted by the first adaption unit 13 in order to maintain their centre frequency close to the frequency of the corresponding tone. Their bandwidth would be adjusted to ensure that it was greater than the tone being attenuated and yet not too broad to let broadband signals through with insufficient delay. This processing being done automatically.
- Figure 3 shows how the sensor signal may be derived from the sensor, 8, in the region to be controlled, 2.
- the output, 17, from the circuit means, 11, which in this figure is identical to that shown in figure 1, is fed to a filter 18.
- the characteristic of this filter is adjusted to correspond to the transfer function between signal 17 and signal 7. This is identical to the filter c(i) used in the first adaption unit 6.
- the output of filter 18 is subtracted from the monitor signal 7 to provide an equivalent signal 3.
- the characteristic of the filter 18 may be updated in order to maintain it as an accurate representation of the transfer function.
- Figure 4 shows the equivalent circuit where the input to the first circuit means and monitor signals are derived from the same sensor for the circuit means 11 which uses narrow-band filters.
- Figure 6 shows the system incorporated in a ear defender.
- the ear defender may be of the open-backed type to allow the desired sounds to reach the ear unimpeded.
- the sensor, 1, generating the input to the first circuit means is a microphone mounted on the shell of the earpiece, 19 and the sensor, 8, generating monitor signals is a microphone contained in the earpiece close to the ear.
- the transducer, 6, is a loudspeaker incorporated in the shell of the earpiece.
- Figure 7 shows a system where one microphone 22, is used to provide the input to the first circuit means for both circuits 11.
- Figure 8 shows the embodiment in which there is no separate sensor to provide an input to the first circuit means (and the input is derived from the monitor signals as described hereinbefore).
- An additional input can be fed to one or each of the loudspeakers carrying desirable communication signals for the wearer and these signals will be converted into sounds for the wearer to hear. These sounds will be unaffected by the citcuit means, 11.
- a microphone would be attached to the headset to receive the wearer's speech.
- the effective delay can be achieved by introducing a delay into the signal either before, during or after adaptive filtering or any combination thereof.
- some or all of the delay introduced by device 4 can be incorporated in the filter 5 or achieved by a discrete device located between the filter 5 and the transducer 6.
- the second circuit 76 must of course be adjusted accordingly.
- N can be any number, and as indicated above ri is the number of sampling points by which one signal is offset from the other.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Health & Medical Sciences (AREA)
- Audiology, Speech & Language Pathology (AREA)
- General Health & Medical Sciences (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
- Noise Elimination (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9003938 | 1990-02-21 | ||
GB909003938A GB9003938D0 (en) | 1990-02-21 | 1990-02-21 | Noise reducing system |
PCT/GB1991/000265 WO1991013429A1 (en) | 1990-02-21 | 1991-02-20 | Noise reducing system |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0516695A1 true EP0516695A1 (en) | 1992-12-09 |
EP0516695B1 EP0516695B1 (en) | 1997-04-09 |
Family
ID=10671394
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP91904859A Expired - Lifetime EP0516695B1 (en) | 1990-02-21 | 1991-02-20 | Noise reducing system |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP0516695B1 (en) |
JP (1) | JPH07500677A (en) |
AT (1) | ATE151554T1 (en) |
AU (1) | AU639761B2 (en) |
CA (1) | CA2076390C (en) |
DE (1) | DE69125601T2 (en) |
GB (1) | GB9003938D0 (en) |
WO (1) | WO1991013429A1 (en) |
Families Citing this family (27)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3506440B2 (en) | 1991-08-05 | 2004-03-15 | 富士通テン株式会社 | Noise control device |
GB2274757A (en) * | 1993-01-28 | 1994-08-03 | Secr Defence | Ear defenders employing active noise control |
US5386477A (en) * | 1993-02-11 | 1995-01-31 | Digisonix, Inc. | Active acoustic control system matching model reference |
US5481615A (en) * | 1993-04-01 | 1996-01-02 | Noise Cancellation Technologies, Inc. | Audio reproduction system |
AU2007233675B2 (en) | 2006-04-01 | 2010-11-25 | Widex A/S | Hearing aid, and a method for control of adaptation rate in anti-feedback systems for hearing aids |
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 |
US8908877B2 (en) | 2010-12-03 | 2014-12-09 | Cirrus Logic, Inc. | Ear-coupling detection and adjustment of adaptive response in noise-canceling in personal audio devices |
WO2012075343A2 (en) | 2010-12-03 | 2012-06-07 | Cirrus Logic, Inc. | Oversight control of an adaptive noise canceler in a personal audio device |
JP2014533444A (en) | 2011-06-01 | 2014-12-11 | フィテック システムズ リミテッドPhitek Systems Limited | In-ear device incorporating active noise reduction |
US8958571B2 (en) | 2011-06-03 | 2015-02-17 | Cirrus Logic, Inc. | MIC covering detection in personal audio devices |
US9318094B2 (en) | 2011-06-03 | 2016-04-19 | Cirrus Logic, Inc. | Adaptive noise canceling architecture for a personal audio device |
US9824677B2 (en) * | 2011-06-03 | 2017-11-21 | Cirrus Logic, Inc. | Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (ANC) |
US8948407B2 (en) | 2011-06-03 | 2015-02-03 | Cirrus Logic, Inc. | Bandlimiting anti-noise in personal audio devices having adaptive noise cancellation (ANC) |
US9325821B1 (en) | 2011-09-30 | 2016-04-26 | Cirrus Logic, Inc. | Sidetone management in an adaptive noise canceling (ANC) system including secondary path modeling |
US9319781B2 (en) | 2012-05-10 | 2016-04-19 | Cirrus Logic, Inc. | Frequency and direction-dependent ambient sound handling in personal audio devices having adaptive noise cancellation (ANC) |
US9123321B2 (en) | 2012-05-10 | 2015-09-01 | Cirrus Logic, Inc. | Sequenced adaptation of anti-noise generator response and secondary path response in an adaptive noise canceling system |
US9318090B2 (en) | 2012-05-10 | 2016-04-19 | Cirrus Logic, Inc. | Downlink tone detection and adaptation of a secondary path response model in an adaptive noise canceling system |
US9532139B1 (en) | 2012-09-14 | 2016-12-27 | Cirrus Logic, Inc. | Dual-microphone frequency amplitude response self-calibration |
US9369798B1 (en) | 2013-03-12 | 2016-06-14 | Cirrus Logic, Inc. | Internal dynamic range control in an adaptive noise cancellation (ANC) system |
US9414150B2 (en) | 2013-03-14 | 2016-08-09 | Cirrus Logic, Inc. | Low-latency multi-driver adaptive noise canceling (ANC) system for a personal audio device |
US9502020B1 (en) | 2013-03-15 | 2016-11-22 | Cirrus Logic, Inc. | Robust adaptive noise canceling (ANC) in a personal audio device |
US9578432B1 (en) | 2013-04-24 | 2017-02-21 | Cirrus Logic, Inc. | Metric and tool to evaluate secondary path design in adaptive noise cancellation systems |
US9369557B2 (en) | 2014-03-05 | 2016-06-14 | Cirrus Logic, Inc. | Frequency-dependent sidetone calibration |
US9319784B2 (en) | 2014-04-14 | 2016-04-19 | Cirrus Logic, Inc. | Frequency-shaped noise-based adaptation of secondary path adaptive response in noise-canceling personal audio devices |
JP6964581B2 (en) | 2015-08-20 | 2021-11-10 | シーラス ロジック インターナショナル セミコンダクター リミテッド | Feedback Adaptive Noise Cancellation (ANC) Controllers and Methods with Feedback Responses Partially Provided by Fixed Response Filters |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ZA824145B (en) * | 1981-06-12 | 1983-04-27 | Sound Attenuators Ltd | Method and apparatus for reducing repetitive noise entering the ear |
GB8517716D0 (en) * | 1985-07-13 | 1985-08-21 | Plessey Co Plc | Noise reduction arrangements |
US4985925A (en) * | 1988-06-24 | 1991-01-15 | Sensor Electronics, Inc. | Active noise reduction system |
-
1990
- 1990-02-21 GB GB909003938A patent/GB9003938D0/en active Pending
-
1991
- 1991-02-20 AU AU73360/91A patent/AU639761B2/en not_active Ceased
- 1991-02-20 EP EP91904859A patent/EP0516695B1/en not_active Expired - Lifetime
- 1991-02-20 CA CA002076390A patent/CA2076390C/en not_active Expired - Fee Related
- 1991-02-20 WO PCT/GB1991/000265 patent/WO1991013429A1/en active IP Right Grant
- 1991-02-20 AT AT91904859T patent/ATE151554T1/en not_active IP Right Cessation
- 1991-02-20 DE DE69125601T patent/DE69125601T2/en not_active Expired - Fee Related
- 1991-02-20 JP JP3505505A patent/JPH07500677A/en active Pending
Non-Patent Citations (1)
Title |
---|
See references of WO9113429A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO1991013429A1 (en) | 1991-09-05 |
AU639761B2 (en) | 1993-08-05 |
DE69125601T2 (en) | 1997-08-14 |
ATE151554T1 (en) | 1997-04-15 |
JPH07500677A (en) | 1995-01-19 |
GB9003938D0 (en) | 1990-04-18 |
DE69125601D1 (en) | 1997-05-15 |
CA2076390A1 (en) | 1991-08-22 |
AU7336091A (en) | 1991-09-18 |
CA2076390C (en) | 1998-07-14 |
EP0516695B1 (en) | 1997-04-09 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
AU639761B2 (en) | Noise reducing system | |
US5652799A (en) | Noise reducing system | |
Kates | Constrained adaptation for feedback cancellation in hearing aids | |
EP0081516B1 (en) | Method and apparatus for reducing repetitive noise entering the ear | |
JP4888852B2 (en) | Bidirectional communication apparatus having one transducer and method thereof | |
US5937070A (en) | Noise cancelling systems | |
US6078672A (en) | Adaptive personal active noise system | |
US5452361A (en) | Reduced VLF overload susceptibility active noise cancellation headset | |
US11862140B2 (en) | Audio system and signal processing method for an ear mountable playback device | |
WO2001024575A9 (en) | Noise suppression system with dual microphone echo cancellation | |
CA2424093A1 (en) | Method and device for acoustic shock protection | |
WO1997025790A3 (en) | Noise cancellation and noise reduction apparatus | |
CN114787911A (en) | Noise elimination system and signal processing method of ear-wearing type playing device | |
US3098121A (en) | Automatic sound control | |
EP0643881B1 (en) | Active plus selective headset | |
JP7164794B2 (en) | Hearing protection system with self-speech estimation and related methods | |
Håkansson et al. | Noise Canceling Headsets for Speech Communication | |
JP3128870B2 (en) | Noise reduction device | |
WO1993025167A1 (en) | Active selective headset | |
US11678105B2 (en) | Noise canceling headphones | |
CN117177120A (en) | Noise-reducing audio earphone | |
Rubak et al. | Adaptive noise cancelling in headsets | |
JPH05188977A (en) | Noise controller | |
EP0643880A1 (en) | Active/passive headset with speech filter | |
EP0643571A1 (en) | Active selective headset |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 19920908 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE |
|
19A | Proceedings stayed before grant |
Effective date: 19930430 |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: 712A |
|
19F | Resumption of proceedings before grant (after stay of proceedings) |
Effective date: 19950220 |
|
17Q | First examination report despatched |
Effective date: 19950510 |
|
GRAG | Despatch of communication of intention to grant |
Free format text: ORIGINAL CODE: EPIDOS AGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: CH Effective date: 19970409 Ref country code: LI Effective date: 19970409 Ref country code: AT Effective date: 19970409 Ref country code: GR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 19970409 Ref country code: ES Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY Effective date: 19970409 Ref country code: DK Effective date: 19970409 |
|
REF | Corresponds to: |
Ref document number: 151554 Country of ref document: AT Date of ref document: 19970415 Kind code of ref document: T |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: EP |
|
ITF | It: translation for a ep patent filed | ||
REF | Corresponds to: |
Ref document number: 69125601 Country of ref document: DE Date of ref document: 19970515 |
|
ET | Fr: translation filed | ||
REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LU Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 19980220 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: BE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 19980228 |
|
26N | No opposition filed | ||
BERE | Be: lapsed |
Owner name: NOISE CANCELLATION TECHNOLOGIES INC. Effective date: 19980228 |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: IF02 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20070105 Year of fee payment: 17 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NL Payment date: 20070108 Year of fee payment: 17 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: SE Payment date: 20070205 Year of fee payment: 17 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20070228 Year of fee payment: 17 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: IT Payment date: 20070529 Year of fee payment: 17 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20070201 Year of fee payment: 17 |
|
EUG | Se: european patent has lapsed | ||
GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 20080220 |
|
NLV4 | Nl: lapsed or anulled due to non-payment of the annual fee |
Effective date: 20080901 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20080901 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST Effective date: 20081031 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20080221 Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20080902 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20080229 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20080220 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20080220 |