34 results about "Adaptive feedback cancellation" patented technology

A personal audio device, such as a wireless telephone, includes noise canceling circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone may also be provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit that performs the adaptive noise canceling (ANC) function also detects frequency-dependent characteristics in and / or direction of the ambient sounds and alters adaptation of the noise canceling circuit in response to the detection.

An improved method for adaptively cancelling acoustic feedback in hearing aids and other audio amplification devices. Feedback cancellation is limited to a frequency band that encompasses all unstable frequencies. By limiting the bandwidth of the feedback cancellation signal, the distortion due to the adaptive filter is minimized and limited only to the unstable feedback regions. A relatively simple signal processing algorithm is used to produce highly effective results with minimal signal distortion.

A hearing aid comprises an input transducer (2), a subtraction node for subtracting a feedback cancellation signal from the electrical input signal thereby generating a processor input signal, a signal processor (3), an output transducer (4), a pair of equalization filters (7a, 7b) for selecting from the processor input and output signals a plurality of frequency band signals, a frequency equalization unit for frequency equalization for the selected frequency band signals, and an adaptive feedback estimation filter (5, 6) for adaptively deriving the feedback cancellation signal from the equalized frequency band signals. The equalization of selected frequency bands of the input signals of the adaptive feedback cancellation filter provides for an improved and in particular a faster adaption of the feedback cancellation. The invention further provides a method of reducing acoustic feedback of a hearing aid, and a hearing aid circuit.

A hearing aid comprises at least one microphone (M) for converting input sound into an input signal, a subtraction node for subtracting a feedback cancellation signal from the input signal thereby generating a processor input signal, a hearing aid processor (G) for producing a processor output signal by applying an amplification gain to the processor input signal, a receiver (R) for converting the processor output signal into output sound, an adaptive feedback cancellation filter for adaptively deriving the feedback cancellation signal from the processor output signal by applying filter coefficients, calculation means for calculating the autocorrelation of a reference signal, and an adaptation means for adjusting the filter coefficients with an adaptation rate, wherein the adaptation rate is controlled in dependency of the autocorrelation of the reference signal.

The invention relates to an audio processing system for processing an input sound to an output sound. The invention further relates to a method of estimating a feedback transfer function in an audio processing system. The object of the present invention is to provide an alternative scheme for minimizing feedback in audio processing systems. The problem is solved in that the audio processing system comprises an input transducer for converting an input sound to an electric input signal and defining an input side, an output transducer for converting a processed electric output signal to an output sound and defining an output side, a forward path being defined between the input transducer and the output transducer, and comprising a signal processing unit adapted for processing an SPU-input signal originating from the electric input signal and to provide a processed SPU-output signal, and an electric feedback loop from the output side to the input side comprising a feedback path estimation unit for estimating an acoustic feedback transfer function from the output transducer to the input transducer, and a enhancement unit for estimating noise-like signal components in the electric signal of the forward path and providing a noise signal estimate output, wherein the feedback path estimation unit is adapted to use the noise signal estimate output in the estimation of the acoustic feedback transfer function. This has the advantage of providing an adaptive feedback cancellation system which is robust in situations with a high degree of correlation between the output signal and the input signal of an audio processing system, e.g. a listening device. The invention may e.g. be used in public address systems, entertainment systems, hearing aids, head sets, mobile phones, wearable / portable communication devices, etc.

The present invention discloses an adaptive feedback cancellation based on inserted and / or intrinsic characteristics and matched retrieval, which is realized by an audio processing system used for processing the input sound to output sound and a method for estimating a feedback transfer function in the audio processing system. The audio processing system comprises the following components: an input transducer; an output transducer; a forward path which comprises a signal processing unit; an electric feedback loop which extends from an output side and an input side and comprises a feedback path estimation unit which is used for estimating a sound feedback transfer function from the output transducer to the input transducer; and an enhancement unit which is used for extracting the characteristic of the electrical signal of the forward path and providing the estimated characteristic output; wherein the feedback path estimation unit is suitable for estimating the sound feedback transfer function with the estimated characteristic output. The invention can minimize the feedback in an audio processing system and may e.g. be used in hearing aids, head sets, mobile phones, wearable / portable communication devices, etc.

An improved method for adaptively cancelling acoustic feedback in hearing aids and other audio amplification devices. Feedback cancellation is limited to a frequency band that encompasses all unstable frequencies. By limiting the bandwidth of the feedback cancellation signal, the distortion due to the adaptive filter is minimized and limited only to the unstable feedback regions. A relatively simple signal processing algorithm is used to produce highly effective results with minimal signal distortion.

A method and an audio processing system determine a system parameter, e.g. step size, in an adaptive algorithm, e.g. an adaptive feedback cancellation algorithm so as to provide an alternative scheme for feedback estimation in a multi-microphone audio processing system. A feedback part of the system's open loop transfer function is estimated and separated in a transient part and a steady state part, which can be used to control the adaptation rate of the adaptive feedback cancellation algorithm by adjusting the system parameter, e.g. step size parameter, of the algorithm when desired system properties, such as a steady state value or a convergence rate of the feedback, are given / desired. The method can be used for different adaptation algorithms such as LMS, NLMS, RLS, etc. in hearing aids, headsets, handsfree telephone systems, teleconferencing systems, public address systems, etc.

A method and system for active noise cancellation is provided. The system employs subband processing, and preferably implements over-sampled filterbank. The system is applicable to adaptive noise cancellation, adaptive echo cancellation for portable listening devices, such as headsets and other similar listening devices.

A system and method for adaptively removing feedback in audio systems and, more particularly, hearing aid systems. The audio system comprises an analysis unit, for receiving an input signal and providing N bandpass input signals, and an adaptive feedback cancellation unit for removing a feedback condition in one or more of the N bandpass input signals. The adaptive feedback cancellation unit comprises N sub-units with at least one of the sub-units including: (i) a feedback detector for indicating the presence of the feedback condition in one of the bandpass input signals, (ii) an adaptive feedback canceller for providing an adaptive gain modification factor for adjusting gain when the feedback condition is detected within one of the bandpass input signals, and (iii) a multiplier coupled to the adaptive feedback canceller and the analysis unit for providing a bandpass output signal based on one of the bandpass input signals and the corresponding adaptive gain modification factor.

A method and apparatus for enhancing the performance of an in-the-canal hearing aid by temporarily increasing the adaptation speed of an adaptive feedback cancellation filter in response to sudden changes in the acoustic feedback path. The hearing aid employs a sound producing transducer (e.g., a speaker) mounted in a user's open ear canal along with a sound responsive transducer (e.g., a microphone) and a second sound responsive transducer also mounted in the ear canal and spaced a fixed distance from the first sound responsive transducer. The output signals from the first and second sound responsive transducers are applied to a digital processor which compares the respective output signals to detect impedance changes in the audio feedback path. The detected occurrence of an impedance change is then used to influence the adaptation speed of the adaptive feedback cancellation filter.

The invention discloses a fitting device for fitting a hearing device to compensate for the hearing loss of a user and to a corresponding method. Additionally, the invention relates to a hearing device of reducing feedback and to a corresponding hearing device. The hearing device comprises a receiver and a microphone; wherein a feedback path from the receiver to the microphone exists; wherein the hearing device further comprises an adaptive feedback canceller adapted to reduce at least a part of the feedback; and wherein the adaptive feedback canceller comprises a fixed filter for modeling an invariant portion of the feedback path, and an adaptive filter for modeling a variant portion of the feedback path; and wherein the invariant portion is provided to the fixed filter of the hearing device independently of an actual user using the hearing device and the acoustical environment where the hearing device is put into use. Thereby a hearing aid is achieved which contains a fixed filter which comprises the invariant portions of the feedback path.

The invention regards a scheme for generating a probe noise signal to be used in an anti feedback system of an audio system. The audio system comprises e.g. a microphone for capturing an audio signal, an audio signal processor for adaptation of the audio signal and a receiver for generation of an audible signal. According to an embodiment of the invention, a noise signal is injected into the audio signal path between the microphone and the receiver and used for estimating acoustical feedback, the noise signal being generated by the following steps:converting a digitized audio signal to the frequency domain, in order to obtain a series of magnitude and phase values,changing the phase values such that the phase of the resulting signal becomes less correlated, preferably substantially un-correlated, to the original signal,converting the magnitude and phase back to a time domain signal using the changed phase values.The invention may e.g. be used in a hearing aid, a headset or a pair of headphones.

A hearing aid includes: a feedback monitor connected to the adaptive feedback canceller and configured to monitor a state of feedback and having an output providing an indication of the state of feedback; and a cue controller connected to the feedback monitor and the at least one adaptive cue filter, and configured to control, in response to an output of the feedback monitor, the at least one adaptive cue filter so that the difference between the output of the at least one ITE microphone and the combined output of the at least one adaptive cue filter is reduced.

This invention concerns a method, and a device, for feedback cancellation. This invention also concerns a computer program product comprising computer program code means to make a computer execute a procedure for feedback cancellation. The method comprises providing an adaptive feedback cancellation filter which adapts under the control of a control module, and filtering at least one input of the control module to suppress correlated signals from the input prior to the control module operating upon the input. The device comprises an adaptive feedback cancellation filter, a control module and at least one filter. The control module controls adaptation of the adaptive feedback cancellation filter. The filter suppresses correlated signals from an input to the control module prior to the control module operating upon the input.

The invention relates to an audio processing system for processing an input sound to an output sound. The invention further relates to a method of estimating a feedback transfer function in an audio processing system. The object of the present invention is to provide an alternative scheme for minimizing feedback in audio processing systems. The problem is solved in that the audio processing system comprises an input transducer for converting an input sound to an electric input signal and defining an input side, an output transducer for converting a processed electric output signal to an output sound and defining an output side, a forward path being defined between the input transducer and the output transducer, and comprising a signal processing unit adapted for processing an SPU-input signal originating from the electric input signal and to provide a processed SPU-output signal, and an electric feedback loop from the output side to the input side comprising a feedback path estimation unit for estimating an acoustic feedback transfer function from the output transducer to the input transducer, and a enhancement unit for estimating noise-like signal components in the electric signal of the forward path and providing a noise signal estimate output, wherein the feedback path estimation unit is adapted to use the noise signal estimate output in the estimation of the acoustic feedback transfer function. This has the advantage of providing an adaptive feedback cancellation system which is robust in situations with a high degree of correlation between the output signal and the input signal of an audio processing system, e.g. a listening device. The invention may e.g. be used in public address systems, entertainment systems, hearing aids, head sets, mobile phones, wearable / portable communication devices, etc.

This invention concerns a method, and a device, for feedback cancellation. This invention also concerns a computer program product comprising computer program code means to make a computer execute a procedure for feedback cancellation. The method comprises providing an adaptive feedback cancellation filter which adapts under the control of a control module, and filtering at least one input of the control module to suppress correlated signals from the input prior to the control module operating upon the input. The device comprises an adaptive feedback cancellation filter, a control module and at least one filter. The control module controls adaptation of the adaptive feedback cancellation filter. The filter suppresses correlated signals from an input to the control module prior to the control module operating upon the input.

A hearing aid comprises an input transducer (2), a subtraction node for subtracting a feedback cancellation signal from the electrical input signal thereby generating a processor input signal, a signal processor (3), an output transducer (4), a pair of equalization filters (7a, 7b) for selecting from the processor input and output signals a plurality of frequency band signals, a frequency equalization unit for frequency equalization for the selected frequency band signals, and an adaptive feedback estimation filter (5, 6) for adaptively deriving the feedback cancellation signal from the equalized frequency band signals. The equalization of selected frequency bands of the input signals of the adaptive feedback cancellation filter provides for an improved and in particular a faster adaption of the feedback cancellation. The invention further provides a method of reducing acoustic feedback of a hearing aid, and a hearing aid circuit.

Methods and systems for signal processing an audio signal in a hearing device to detect when feedback path change occurs and controlling an adaptive feedback canceler to remove the feedback are provided. The hearing device includes a receiver and a microphone. An exemplary method includes detecting whether a tonal signal is caused by a feedback path change by estimating a product of a subband error signal and a subband output signal generated in response to a subband audio input signal; estimating a fast metric based on the estimated product and estimating a slow metric; and applying or maintaining an adaptation rate to the adaptive feedback canceler of the hearing device, wherein the adaptation rate applied or maintained is selected based upon a value of the difference between the fast and slow metrics compared to a threshold value.

The invention discloses a sub-band adaptive feedback elimination method and system based on step length control. The method comprises the following steps: acquiring a microphone pickup signal d (n) and a loudspeaker output delay signal x (n); performing pre-emphasis processing, sub-band filtering processing and FFT conversion on the signal d (n) and the signal x (n) in sequence; performing frequency-domain filtering processing to obtain a frequency-domain difference signal E (f, k); updating a frequency-domain filter coefficient; after the frequency-domain difference signal E (f, k) is converted to a time domain through IFFT, obtaining a time-domain signal e (n) through sub-band synthesis filtering processing and signal de-emphasis processing in sequence; and performing frequency shift processing on the time-domain signal e (n) to obtain a loudspeaker output signal y (n). According to the method, a sub-band adaptive algorithm is used, a high effect can be achieved with the minimum filter length, meanwhile, a large amount of calculation is reduced, and the processing efficiency is improved.

Systems and methods for acoustic feedback cancellation. One method includes transmitting, with a transceiver, a known full-band sequence at a first time. The method includes receiving, via a microphone, a received audio signal including a received copy of the known full-band sequence. The method includes filtering the received audio signal to generate a filtered audio signal, and detecting, based on the filtered audio signal, a second portable communication device in proximity to the portable communication device. The method includes, in response to detecting the second portable communication device, determining, based on the first time and filtered audio signal, an estimated loop delay. The method includes initializing an adaptive feedback cancellation filter based on the estimated loop delay and the plurality of estimated filter coefficients. The method includes determining a plurality of estimated filter coefficients based on the known full-band sequence and the received copy of the known full-band sequence.

A method and an audio processing system determine a system parameter, e.g. step size, in an adaptive algorithm, e.g. an adaptive feedback cancellation algorithm so as to provide an alternative scheme for feedback estimation in a multi-microphone audio processing system. A feedback part of the system's open loop transfer function is estimated and separated in a transient part and a steady state part, which can be used to control the adaptation rate of the adaptive feedback cancellation algorithm by adjusting the system parameter, e.g. step size parameter, of the algorithm when desired system properties, such as a steady state value or a convergence rate of the feedback, are given / desired. The method can be used for different adaptation algorithms such as LMS, NLMS, RLS, etc. in hearing aids, headsets, handsfree telephone systems, teleconferencing systems, public address systems, etc.

Methods and systems for signal processing an audio signal in a hearing device to detect when feedback path change occurs and controlling an adaptive feedback canceler to remove the feedback are provided. The hearing device includes a receiver and a microphone. An exemplary method includes detecting whether a tonal signal is caused by a feedback path change by estimating a product of a subband error signal and a subband output signal generated in response to a subband audio input signal; estimating a fast metric based on the estimated product and estimating a slow metric; and applying or maintaining an adaptation rate to the adaptive feedback canceler of the hearing device, wherein the adaptation rate applied or maintained is selected based upon a value of the difference between the fast and slow metrics compared to a threshold value.

A hearing aid includes: a feedback monitor connected to the adaptive feedback canceller and configured to monitor a state of feedback and having an output providing an indication of the state of feedback; and a cue controller connected to the feedback monitor and the at least one adaptive cue filter, and configured to control, in response to an output of the feedback monitor, the at least one adaptive cue filter so that the difference between the output of the at least one ITE microphone and the combined output of the at least one adaptive cue filter is reduced.

The invention relates to the technical field of acoustics, in particular to a method and system for adaptive acoustic feedback elimination based on transform domain. A method and system for adaptive acoustic feedback elimination based on the transform domain of the present invention, through audio signal acquisition, signal time-frequency conversion, self-tuning coefficient calculation, autocorrelation matrix calculation, matrix equation fast solution, frequency domain filtering, feedback The steps of elimination, filter coefficient update, and signal time-frequency inverse transformation realize adaptive acoustic feedback elimination. The invention realizes the elimination of acoustic feedback and can reduce the damage to the target audio signal, and can obtain better feedback elimination effect and maintain higher audio quality under the environment of dynamic change of the feedback path. This technology uses the principle of algorithm to estimate the transfer function of the feedback path to separate the target audio signal from the feedback signal, so as to achieve feedback elimination, and the specific type of feedback path, the number of various feedback paths, the target sound source and the feedback sound source It is independent of the spatial topology of the audio and does not produce large audio impairments.

The invention discloses a hearing aid device and a method for fitting a hearing aid device to compensate a user's hearing loss to reduce feedback. The present invention relates to a hearing aid device comprising a receiver and a microphone; wherein there is a feedback path from the receiver to the microphone; wherein the hearing aid device further comprises an adaptive feedback canceller adapted to reduce at least a portion of the feedback; and wherein the adaptive feedback The canceller includes a fixed filter for modeling the constant part of the feedback path and an adaptive filter for modeling the changing part of the feedback path; The acoustic environment in which the hearing device is put into use will provide a constant part to the fixed filter of the hearing aid. Hereby is achieved a hearing aid comprising a fixed filter comprising a constant part of the feedback path.

A signal processing device comprises: input transducer(s) configured to convert input(s) to an input signal; output transducer(s) configured to convert an output signal to output(s); a signal processing circuit configured to at least subtract a feedback estimation signal from the input signal to produce a feedback compensated signal; and an adaptive feedback estimator. The adaptive feedback estimator comprises processor(s) and machine readable medium(s) collectively comprising instructions configured to cause the processor(s) to: estimate feedback path characteristic(s); construct an adaptive feedback cancellation filter based at least in part on the feedback path characteristic(s); select a value for variable p in a diversity measure norm; compute an update rule for the adaptive feedback cancellation filter, the update rule based on the diversity measure norm; apply the update rule to the adaptive feedback cancellation filter; and generate the feedback estimation signal through employment of the adaptive feedback cancellation filter on the output signal.

The present subject matter can improve robustness of performance of acoustic feedback cancellation in the presence of strong acoustic disturbances. In various embodiments, an optimization criterion determined to enhance robustness of an adaptive feedback canceller in an audio device against disturbances in an incoming audio signal can be applied such that the adaptive feedback controller remains in a converged state in response to presence of the disturbances.