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381 - Electrical audio signal processing systems and devices

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DocumentTitleDate
20110002473DEREVERBERATION APPARATUS, DEREVERBERATION METHOD, DEREVERBERATION PROGRAM, AND RECORDING MEDIUM - A sound source model storage section stores a sound source model that represents an audio signal emitted from a sound source in the form of a probability density function. An observation signal, which is obtained by collecting the audio signal, is converted into a plurality of frequency-specific observation signals each corresponding to one of a plurality of frequency bands. Then, a dereverberation filter corresponding to each frequency band is estimated by using the frequency-specific observation signal for the frequency band on the basis of the sound source model and a reverberation model that represents a relationship for each frequency band among the audio signal, the observation signal and the dereverberation filter. A frequency-specific target signal corresponding to each frequency band is determined by applying the dereverberation filter for the frequency band to the frequency-specific observation signal for the frequency band, and the resulting frequency-specific target signals are integrated.01-06-2011
20130044890INFORMATION PROCESSING DEVICE, INFORMATION PROCESSING METHOD AND PROGRAM - n information processing device includes: an estimating section which estimates an amplitude frequency function from a first signal output to a speaker and a second signal input from a microphone; a generating section which generates an estimated echo signal from the first signal and the amplitude frequency function; and a suppressing section which suppresses the estimated echo signal from the second signal, wherein the estimating section changes a coefficient of the amplitude frequency function on the basis of the correlation between the estimated amplitude frequency function and a short-time average amplitude frequency function.02-21-2013
20110176687APPARATUS AND ASSOCIATED METHODOLOGY FOR SUPPRESSING AN ACOUSTIC ECHO - A new acoustic echo suppressor and method for acoustic echo suppression is described herein. Exemplary embodiments of the acoustic echo suppressor use one linear regression model for each subband. The linear regression model for each subband may operate on the squared magnitude of the input samples as well as corresponding cross-products. In this way, accurate and robust estimates of the echo signal in each subband can be obtained, thereby providing good echo reduction while keeping the signal distortion low07-21-2011
20130028432REVERBERATION SUPPRESSION DEVICE, REVERBERATION SUPPRESSION METHOD, AND COMPUTER-READABLE RECORDING MEDIUM STORING REVERBERATION SUPPRESSION PROGRAM - A reverberation suppression device includes, a first storage unit configured to store, in advance, information representing a first impulse response obtained from a signal output from a microphone when a sound source positioned according to directivity of either a speaker or the microphone, which are mounted on a mobile terminal, outputs an impulse; a second storage unit configured to store information representing a second impulse response obtained from a signal output from the microphone when the speaker mounted on the mobile terminal outputs an impulse in a room where reverberation sound is to be suppressed; a response correction unit configured to obtain a corrected impulse response, which reflects the room's environment, by correcting the second impulse response, which is represented by the information stored in the second storage unit, using the information representing the first impulse response; and a sound correction unit configured to correct a sound signal01-31-2013
20130028431MULTIFUNCTIONAL ELECTRONIC ACCESSORY - An electronic accessory for an electronic device includes an audio processing circuit. The audio processing circuit includes a first switch circuit, an echo cancellation circuit and an amplification circuit. The echo cancellation circuit removes echoes from a first voice signal from a user in a call and a second voice signal from a caller, outputs the first voice signal to the electronic device via the first switch circuit, and outputs the second voice signal to the amplification circuit. The amplification circuit amplifies the second voice signal. The amplification circuit further directly receives and amplifies a third voice signal from multimedia content stored in the electronic device via the first switch circuit.01-31-2013
20090123002System and method for providing step size control for subband affine projection filters for echo cancellation applications - A system and method for Acoustic Echo Cancellation. The system and method include a subband affine projection filter and a variable step size controller configured to cancel an estimated echo from a near-end signal. The system and method also include a divergence detector adapted to reset the subband affine projection filter in response to determining a divergence is occurring. Additionally, the system and method include a double talk detector adapted to transmit a signal to mask an output signal when double talk is detected.05-14-2009
20100074452ACOUSTIC ECHO CONTROL - Processing requirements for echo cancellation in voice communications are significant and are even more so as the bandwidth of the communication increases. Whilst voice communication occupies a relatively narrow band of frequencies the processing requirements and so forth for wideband communication render echo cancellation difficult to achieve in a cost effective manner. The invention provides for provides echo cancellation within wideband communications by dividing the communications into sub-bands and applying echo cancellation to some sub-bands whilst processing other sub-bands according to the status of the communications. Additional sub-bands are transmitted at either full-duplex or half-duplex.03-25-2010
20130039503BEAMFORMING APPARATUS AND METHOD BASED ON LONG-TERM PROPERTIES OF SOURCES OF UNDESIRED NOISE AFFECTING VOICE QUALITY - A beamforming technique for a microphone array is described to attenuate a source of undesired noise that is deemed the most limiting to audio quality in an acoustic environment. Possible sources of undesired noise include echo, background noise (stationary) and other interference signals (non-stationary). The beamforming technique is updated based on long-term evaluations. Once an evaluation occurs and a decision is made, the beamformer adapts with a maximum responsiveness and without intentional delay, and therefore not affecting the beamformer's tracking ability. When fixed beamforming is utilized, one of several fixed beamformers having different attenuation targets are selected to implement noise attenuation. When adaptive beamforming is utilized, the beamformer adapts whenever the selected target is deemed dominant.02-14-2013
20100046768METHOD AND SYSTEM FOR ELIMINATION OF ACOUSTIC FEEDBACK - A method and system is provided for eliminating acoustical feedback in a system. The method determines a parameter for at least one notch filter, adjusting the notch filter based on the parameter, processing the digital signals through the notch filter, testing at the effect of the notch filter in the system, and removing the notch filter if the notch filter is not effective. Also disclosed is a method and system of selecting candidate frequencies which might be feedback, as opposed to other wanted sound frequencies. The selection method sampling the digital signals, converting the time domain digital signal samples by a fast Fourier transform algorithm into the frequency domain, using a ballistics approach to find prominences in the frequency spectrum, and testing the sizes of the prominences.02-25-2010
20130077798REVERBERATION SUPPRESSION DEVICE, REVERBERATION SUPPRESSION METHOD, AND COMPUTER-READABLE STORAGE MEDIUM STORING A REVERBERATION SUPPRESSION PROGRAM - A reverberation suppression device includes an analyzer configured to analyze change over time in the power of an input signal obtained from a microphone in response to sound input, and thereby compute the decrease per unit time in the power of the input signal in a reverb segment following the end of a segment in which the sound is produced; and a suppression controller configured to control a suppression gain which indicates the rate at which the input signal is attenuated, on the basis of analysis results from the analyzer.03-28-2013
20090154717Echo Suppressing Method and Apparatus06-18-2009
20090304198AUDIO SIGNAL DECORRELATOR, MULTI CHANNEL AUDIO SIGNAL PROCESSOR, AUDIO SIGNAL PROCESSOR, METHOD FOR DERIVING AN OUTPUT AUDIO SIGNAL FROM AN INPUT AUDIO SIGNAL AND COMPUTER PROGRAM - An audio signal decorrelator for deriving an output audio signal from an input audio signal has a frequency analyzer for extracting from the input audio signal a first partial signal descriptive of an audio content in a first audio frequency range and a second partial signal descriptive of an audio content in a second audio frequency range having higher frequencies compared to the second audio frequency range. A partial signal modifier for modifies the first and second partial signals, to obtain first and second processed partial signals, so that a modulation amplitude of a time variant phase shift or time variant delay applied to the first partial signal is higher than that applied to the second partial signal, or for modifying only the first partial signal. A signal combiner combines the first and second processed partial signals, or combines the first processed partial signal and the second partial signal, to obtain an output audio signal.12-10-2009
20130083936Processing Audio Signals - Audio signals are processed for use in a communication event. A data store may be queried to obtain an indication of an echo direction, which relates to a direction from which audio signals output from the audio output are likely to be received at a microphone array (plurality of microphones) of a device. Beamformer coefficients of an adaptive beamformer of the device are determined in dependence upon the received indication of the echo direction. Audio signals are received at the microphone array. The adaptive beamformer applies the determined beamformer coefficients to the received audio signals, thereby generating a beamformer output for use in the communication event. The beamformer coefficients are determined such that echo suppression is applied to audio signals received at the microphone array from the indicated echo direction.04-04-2013
20130083937Speaker Device, Sound Source Simulation System, and Echo Cancellation System - A speaker device includes an enclosure provided with a speaker unit and a bass reflex port, wherein the bass reflex port has an outer opening opened to outside of the enclosure and an inner opening opened to inside of the enclosure, and has a tubular body whose hollow cross-sectional area is gradually reduced along an axial direction of the bass reflex port from its ends to its center, and the tubular body is formed so that a length of the hollow cross-section in one direction does not change along the axial direction, and wherein the inner opening of the bass reflex port is located opposite to the speaker unit, with the bass reflex port sandwiched therebetween.04-04-2013
20100329472REVERBERATION SUPPRESSING APPARATUS AND REVERBERATION SUPPRESSING METHOD - A reverberation suppressing apparatus separating sound source signals based on input signals output from microphones collecting the plurality of sound source signals, includes a sound signal output unit generating sound signals and outputting the generated sound signals, a sound acquiring unit acquiring the input signals from microphones, a first evaluation function calculation unit calculating a separation matrix, the input signals, and the sound source signals, and calculating a first evaluation function, a reverberation component suppressing unit calculating an optimal separation matrix, and suppressing a reverberation component by separating the sound source signals other than the generated sound signals, and a separation matrix updating unit dividing a step-size function, approximating each segment to a linear function, calculating step sizes based on the approximated linear functions, and repeatedly updating the separation matrix so that the degree of separation of the sound source signals exceeds the predetermined value.12-30-2010
20090304197DISTRIBUTED AUDIO SIGNAL PROCESSING SYSTEM HAVING VIRTUAL CHANNELS - A distributed audio signal processing system having a plurality of linked audio signal processing units is disclosed. Each audio signal processing unit has physical channels for receiving and sending local audio signals and a high bandwidth interface for exchanging audio signals with other linked audio signal processing units. Each of the physical channels of each of the audio signal processing units is mapped to a corresponding global channel. Global channels can be combined to form virtual channels that can be processed as a signal channel.12-10-2009
20090110207Method and Apparatus for Speech Dereverberation Based On Probabilistic Models Of Source And Room Acoustics - Speech dereverberation is achieved by accepting an observed signal for initialization (04-30-2009
20130070934ENCASEMENT FOR ABATING ENVIRONMENTAL NOISE, HAND-FREE COMMUNICATION AND NON-INVASIVE MONITORING AND RECORDING - An encasement such as an electronic pillow including a pillow unit encasing at least one error microphone and at least one loudspeaker in electrical connection with a controller unit, the pillow unit also including a power source, and a reference sensing unit including at least one reference microphone in electrical connection with the controller unit, the controller unit including an algorithm for controlling interactions between the error microphone, loudspeaker, and reference microphone. A method of abating unwanted noise, by detecting an unwanted noise with a reference microphone, analyzing the unwanted noise, producing an anti-noise corresponding to the unwanted noise in a pillow, and abating the unwanted noise.03-21-2013
20110013781SYSTEM AND PROCESS FOR REGRESSION-BASED RESIDUAL ACOUSTIC ECHO SUPPRESSION - A regression-based residual echo suppression (RES) system and process for suppressing the portion of the microphone signal corresponding to a playback of a speaker audio signal that was not suppressed by an acoustic echo canceller (AEC). In general, a prescribed regression technique is used between a prescribed spectral attribute of multiple past and present, fixed-length, periods (e.g., frames) of the speaker signal and the same spectral attribute of a current period (e.g., frame) of the echo residual in the output of the AEC. This automatically takes into consideration the correlation between the time periods of the speaker signal. The parameters of the regression can be easily tracked using adaptive methods. Multiple applications of RES can be used to produce better results and this system and process can be applied to stereo-RES as well.01-20-2011
20120224708INFORMATION PROCESSING APPARATUS, AUXILIARY DEVICE THEREFOR, INFORMATION PROCESSING SYSTEM, CONTROL METHOD THEREFOR, AND CONTROL PROGRAM - Disclosed is a noise suppression technology for suppressing various types of noise including unknown noise without storing a large number of noise information in advance.09-06-2012
20090238373System and method for envelope-based acoustic echo cancellation - Systems and methods for envelope-based acoustic echo cancellation in a communication device are provided. In exemplary embodiments, a primary acoustic signal is received via a microphone of the communication device, and a far-end signal is received via a receiver. Frequency analysis is performed on the primary acoustic signal and the far-end acoustic signal to obtain frequency sub-bands. An echo gain mask based on magnitude envelopes of the primary and far-end acoustic signals for each frequency sub-band is generated. A noise gain mask based on at least the primary acoustic signal for each frequency sub-band may also be generated. A combination of the echo gain mask and noise gain mask may then be applied to the primary acoustic signal to generate a masked signal. The masked signal is then output.09-24-2009
20090052683Echo cancellation - Implementations related to echo cancellation are depicted and described herein.02-26-2009
20090010445ECHO SUPPRESSOR, ECHO SUPPRESSING METHOD, AND COMPUTER READABLE STORAGE MEDIUM - An apparatus is provided for suppressing an echo signal included in a measured signal corresponding to a measured sound. In the apparatus, the measured signal and a reference signal in a time domain are transformed into a frequency domain, and calculated for obtaining each value of a ratio and a correlation between the measured signal and the reference signal in the frequency domain. With executing a comparison of the values of the ratio and the correlation, a coefficient is derived, where a product of the coefficient and the measured sound in the frequency domain gives an estimated value of the echo signal. The echo in the measured signal is suppressed with subtracting the estimation of the echo signal from the measured signal, respectively in the frequency domain.01-08-2009
20090010444METHOD AND DEVICE FOR PERSONALIZED VOICE OPERATED CONTROL - An earpiece (01-08-2009
20090268920Cardioid beam with a desired null based acoustic devices, systems and methods - An acoustic device is provided with first and second one or more acoustic elements to generate a first signal that includes mostly undesired audio and substantially void of desired audio, and a second signal that includes desired as well undesired audio respectively. The first one or more acoustic elements are designed and arranged to generate a Cardioid beam with a null at an originating direction of the desired audio. The second one or more acoustic elements are designed and arranged to generate a complementary beam that includes the desired audio. A system is provided with an appropriate signal processing logic to recover the desired audio using the first and second signals. The signal processing logic may practice echo cancellation like techniques or blind signal separation techniques.10-29-2009
20120237047NONLINEAR REFERENCE SIGNAL PROCESSING FOR ECHO SUPPRESSION - An echo suppression system and method, and a computer-readable storage medium that is configured with instructions that when executed carry out echo suppression. Each of the system and the method includes the elements of a linear echo suppressor having a reference signal path, with a nonlinearity introduced in the reference signal path to introduce energy in spectral bands. Unlike an echo canceller, the echo suppression system and method are relatively robust to errors in the introduced nonlinearity.09-20-2012
20110044461APPARATUS AND METHOD FOR COMPUTING CONTROL INFORMATION FOR AN ECHO SUPPRESSION FILTER AND APPARATUS AND METHOD FOR COMPUTING A DELAY VALUE - An embodiment of an apparatus for computing control information for a suppression filter for filtering a second audio signal to suppress an echo based on a first audio signal includes a computer having a value determiner for determining at least one energy-related value for a band-pass signal of at least two temporally successive data blocks of at least one signal of a group of signals. The computer further includes a mean value determiner for determining at least one mean value of the at least one determined energy-related value for the band-pass signal. The computer further includes a modifier for modifying the at least one energy-related value for the band-pass signal on the basis of the determined mean value for the band-pass signal. The computer further includes a control information computer for computing the control information for the suppression filter on the basis of the at least one modified energy-related value.02-24-2011
20090310794AUDIO CONFERENCE APPARATUS AND AUDIO CONFERENCE SYSTEM - To provide an audio conference apparatus and an audio conference system which can smoothly proceed with the audio conference by removing a recursion sound of the conference voice is achieved. An audio conference apparatus 12-17-2009
20120243698Dynamic Beamformer Processing for Acoustic Echo Cancellation in Systems with High Acoustic Coupling - Near-end equipment for a communication channel with far-end equipment. The near-end equipment includes at least one loudspeaker, at least two microphones, a beamformer, and an echo canceller. The communication channel may be in one of a number of communication states including Near-End Only state, Far-End Only state, and Double-Talk state. In one embodiment, when the echo canceller determines that the communication channel is in either the Far-End Only state or the Double-Talk state, the beamformer is configured to generate a nearfield beampattern signal that directs a null towards a loudspeaker. When the echo canceller detects the Near-End Only state, the beamformer is configured to generate a farfield beampattern signal that optimizes reception of acoustic signals from the near-end audio source. Using different beamformer processing for different communication states allows echo cancellation processing to be more successful at reducing echo in the signal transmitted to the far-end equipment.09-27-2012
20110129096METHOD AND SYSTEM FOR REDUCING ACOUSTICAL REVERBERATIONS IN AN AT LEAST PARTIALLY ENCLOSED SPACE - A method of increasing the intelligibility of an audio broadcast in an at least partially enclosed space from at least one amplified audio source. An input microphone receives an incident audio wavefront at a first position in the at least partially enclosed space. An active noise control system is employed to generate a cancelling audio wavefront having a magnitude substantially equal to the magnitude of incident audio wavefront and a phase substantially opposite to the phase of the incident audio wavefront. The cancelling audio wavefront is broadcast at a second position in the at least partially enclosed space adjacent to a reflective surface of the at least partially enclosed space so as to attenuate the incident audio wavefront substantially at or near the reflective surface in order to reduce reverberations of the incident audio wavefront. In this manner, reverberations which could reduce the intelligibility of the audio broadcast to an audience is reduced.06-02-2011
20110293104AUDIO COMMUNICATION DEVICE AND METHOD USING FIXED ECHO CANCELLATION FILTER COEFFICIENTS - Methods, apparatuses, systems, and software are disclosed for providing a phone or other audio communication device with a fixed-path acoustic echo cancellation feature that compensates for a fixed-path acoustic coupling caused by transmission of sound from one or more speakers to one or more microphones through, for instance, the phone body itself.12-01-2011
20090316924ACCOUSTIC ECHO CANCELLATION AND ADAPTIVE FILTERS - In one embodiment, a two-way telecommunication device may perform acoustic echo cancellation on incoming signals. An audio decoding module may produce an audio render signal. An audio capture interface may receive an audio capture signal. A short length adaptive filter may determine a time delay between the audio render signal and the audio capture signal by adaptively predicting a sub-band of the audio capture signal using a corresponding sub-band of the audio render signal.12-24-2009
20090147964APPARATUS AND METHOD FOR REMOVING AN ECHO SIGNAL IN A SIGNAL TRANSMISSION/RECEPTION APPARATUS OF A COMMUNICATION SYSTEM - A method and apparatus for removing an echo signal in a signal transmission/reception apparatus of a communication system are provided. A signal transmission/reception apparatus determines an echo channel impulse response using a reception signal, generates an echo signal removing coefficient using the echo channel impulse response, removes an echo signal from the reception signal using the echo signal removing coefficient, and transmits a signal in which the echo signal is removed.06-11-2009
20090086986EFFICIENT AUDIO SIGNAL PROCESSING IN THE SUB-BAND REGIME - A signal processing system enhances an audio signal. The audio signal is divided into audio sub-band signals. Some audio sub-band signals are excised. Other audio sub-band signals are processed to obtain enhanced audio sub-band signals. At least a portion of the excised audio sub-band signals are reconstructed. The reconstructed audio sub-band signals are synthesized with the enhanced audio sub-band signals to form an enhanced audio signal.04-02-2009
20100080398METHOD AND SYSTEM FOR HEARING DEVICE FITTING - The method for manufacturing an adjusted hearing device (04-01-2010
20090262950MULTI-CHANNEL ACOUSTIC ECHO CANCELLATION SYSTEM AND METHOD - Techniques for multi-channel acoustic echo cancellation include adaptive filtering. An adaptive filter can use a lattice predictor of order M coupled to an adaptive LMS/Newton filter of length N, wherein M10-22-2009
20090274315METHOD AND APPARATUS TO REDUCE NON-LINEAR DISTORTION - Techniques to reduce distortion in acoustic signals in mobile computing devices are described. For example, a mobile computing device may comprise a speaker operative to receive a first signal and output a second signal. The mobile computing device may further comprise a first microphone operative to receive the second signal and a second microphone operative to receive a third signal. An echo canceller may be coupled to the first microphone and the second microphone and may be operative to compare the second signal and the third signal and reduce distortion in the third signal based on the comparison. Other embodiments are described and claimed.11-05-2009
20080260172Echo Canceller and Speech Processing Apparatus - An echo canceller used for hands-free communication systems in which hands-free communication is performed by using a speaker and a microphone is disclosed. The echo canceller includes a step size control unit calculating a step size value in an adaptive filter and an adaptive filter unit estimating an echo component of a feedback path from an input signal to the feedback path by adaptively identifying an impulse response of the feedback path formed by an acoustical coupling and the like of the speaker and the microphone, and subtracting the echo component from an output signal from the feedback path, in which the step size control unit calculates a step size value by using an echo reduction amount defined based on the ratio between the output signal from the feedback path and a residual signal and outputs the value to the adaptive filter unit.10-23-2008
20090103743ECHO CANCELLER - An echo canceller includes a residual signal generation unit, a double talk detection unit, a nonlinear processor, a speech detection unit, and an input/output characteristic change unit. The residual signal generation unit generates a pseudo echo signal, and generates a residual signal by using the pseudo echo signal. The double talk detection unit detects the state of the transmission signal. The nonlinear processor attenuates the residual signal that has been inputted thereto to a signal level which is based on a predetermined input/output characteristic, and that outputs the attenuated residual signal. The speech detection unit detects whether or not speech is included in the reception signal. The input/output characteristic change unit changes the input/output characteristic of the nonlinear processor to a predetermined input/output characteristic when a single talk state has been detected at the double talk detection unit and speech has been detected at the speech detection unit.04-23-2009
20090003615Audio System Providing For Filter Coefficient Copying01-01-2009
20110206212Microphone System and Method of Operating the Same - A microphone system is provided, wherein the microphone system comprises a microphone array comprising a plurality of microphone units each adapted to generate a primary signal indicative of an acoustic wave received from the respective microphone unit, a first echo cancellation unit, an integrator unit, and a combination unit, wherein the microphone system is adapted to generate a first dipole response and a monopole response from the primary signals, wherein the integrator unit is adapted to generate a first integrated dipole response by integrating the first dipole response, wherein the first echo cancellation unit is adapted to generate a first echo cancelled integrated dipole response from the first integrated dipole response, and wherein the combination unit is adapted to combine the monopole response and the first echo cancelled integrated dipole response.08-25-2011
20090169027ECHO SUPPRESSOR - It is an object of the present invention to provide an echo suppressor which is simple in construction in comparison with the conventional echo suppressor, and which can suppress echoes corresponding to the spatial transfer paths, and reduce the amount of calculations necessary to suppress echoes. The echo suppressor is operative under the condition that transfer functions corresponding to spatial transfer paths between two or more loudspeakers (07-02-2009
20080304676METHOD AND SYSTEM FOR CLEAR SIGNAL CAPTURE - A method and system for clear signal capture comprehend several individual aspects that address specific problems in improved ways. In addition, the method and system also comprehend a hands-free implementation that is a practical solution to a very complex problem. Individual aspects comprehended related to echo and noise reduction, and divergence control.12-11-2008
20080310643METHOD AND SYSTEM FOR CLEAR SIGNAL CAPTURE - A method and system for clear signal capture comprehend several individual aspects that address specific problems in improved ways. In addition, the method and system also comprehend a hands-free implementation that is a practical solution to a very complex problem. Individual aspects comprehended related to echo and noise reduction, and divergence control.12-18-2008
20080310644METHOD AND SYSTEM FOR CLEAR SIGNAL CAPTURE - A method and system for clear signal capture comprehend several individual aspects that address specific problems in improved ways. In addition, the method and system also comprehend a hands-free implementation that is a practical solution to a very complex problem. Individual aspects comprehended related to echo and noise reduction, and divergence control.12-18-2008
20120294454MOBILE TERMINAL AND EARPHONE IDENTIFYING METHOD - A mobile phone apparatus 11-22-2012
20120294453METHOD AND APPARATUS FOR REDUCING NOISE PUMPING DUE TO NOISE SUPPRESSION AND ECHO CONTROL INTERACTION - An input signal is processed through noise suppression (NS) and echo control (EC) via a multipath model that reduces noise pumping effects while maintaining EC performance. A copy of a “noisy” input signal is sent to an EC component before the noisy signal is sent to a NS component, which processes the signal first, when there is a consistent noise level for estimation. The copy of the pre-processing noisy signal is sent to the EC component along with a “clean” or “noise-suppressed” signal output from the NS component. The EC component analyzes the noisy signal as if the EC was the first component in the signal chain to determine what actions to take. The EC component then applies these actions to the clean signal received from the NS component.11-22-2012
20120294452METHOD AND APPARATUS FOR REDUCING NOISE PUMPING DUE TO NOISE SUPPRESSION AND ECHO CONTROL INTERACTION - An input signal is processed through noise suppression (NS) and echo control (EC) via a multipath model that reduces noise pumping effects while maintaining EC performance. A copy of a “noisy” input signal is sent to an EC component before the noisy signal is sent to a NS component, which processes the signal first, when there is a consistent noise level for estimation. The copy of the pre-processing noisy signal is sent to the EC component along with a “clean” or “noise-suppressed” signal output from the NS component. The EC component analyzes the noisy signal as if the EC was the first component in the signal chain to determine what actions to take. The EC component then applies these actions to the clean signal received from the NS component.11-22-2012
20080292109Echo Detection - An echo detector includes means (11-27-2008
20090190769SOUND QUALITY BY INTELLIGENTLY SELECTING BETWEEN SIGNALS FROM A PLURALITY OF MICROPHONES - Sound signal reception is improved by utilizing a plurality of microphones to capture sound signals which are then weighed to dynamically adjust signal quality. A first sound signal and a second sound signal are obtained from first and second microphones, respectively, where the first and second sound signals originate from one or more sound sources. A first signal characteristic (e.g., signal power, signal signal-to-noise ratio, etc.) is obtained for the first sound signal and a second signal characteristic is obtained for the second sound signal. The first and second sound signals are weighed or scaled based on their respective first and second signal characteristics. The weighed first and second sound signals are then combined to obtain an output sound signal.07-30-2009
20130216057ECHO CANCELLATION USING CLOSED-FORM SOLUTIONS - A system that utilizes closed-form solutions to perform echo cancellation is described. The system includes a filter, filter parameter determination logic and a combiner. The filter is configured to process a far-end audio signal in accordance with one or more filter parameters to generate an estimated echo signal. The filter parameter determination logic is configured to update estimated statistics associated with the far-end audio signal and a microphone signal based on instantaneous statistics associated with the far-end audio signal and the microphone signal, and calculate the one or more filter parameters based upon the updated estimated statistics. The combiner is configured to generate an estimated near-end audio signal by subtracting the estimated echo signal from the microphone signal.08-22-2013
20130216056NON-LINEAR ECHO CANCELLATION - A two-stage structure for performing non-linear echo cancellation is described in which a first echo canceller is used to attenuate linear echo components of a microphone signal and a second echo canceller is used to attenuate non-linear echo components of the output signal generated by the first echo canceller. One or both of the echo cancellers may be implemented using closed-form solutions, including a closed form solution for a hybrid method in the frequency domain.08-22-2013
20080219463ACOUSTIC ECHO CANCELLATION SYSTEM - An embodiment of an acoustic echo cancellation system is disclosed. The system comprises an echo cancellation unit, a second filter and a subtraction unit. The echo cancellation unit comprises a first attenuator, a first filter and a first subtractor. The first attenuator has a first down-scaling factor for attenuating a first signal. The first filter generates a first echo signal estimate based on the attenuated first signal. The first subtractor generates a third signal by subtracting the first echo signal estimate from a second signal. The second filter generates a second echo signal estimate based on the first signal. The subtraction unit subtracts the second echo signal estimate from the third signal.09-11-2008
20090161884ETHERNET ISOLATOR FOR MICROPHONICS SECURITY AND METHOD THEREOF - A system and method for providing microphonic isolation on a transmission line. The transmission line has a first part and a second part. The first part of transmission line carries a data signal and a microphonic signal. The microphonic signal has frequencies that include those in a range of substantially 20 Hz to substantially 20 kHz. The system includes an isolation apparatus. The isolation apparatus has an input in electrical communication with a first part of the transmission line, an output in electrical communication with the second part of the transmission line, and a filter in electrical communication with the input and the output. The filter is arranged to substantially remove the microphonic signal received at the input from first part of transmission line and pass the data signal to the output.06-25-2009
20090185695METHOD AND SYSTEM FOR CLOCK DRIFT COMPENSATION - Different sampling rates between a playout unit and a capture unit are compensated for via a system, method and computer program product. The playout unit receives samples from a computational unit, and the capture unit sends samples to the computational unit. A playout FIFO buffer operates in a playout time domain, and a capture FIFO buffer operates in a capture time domain. The computational unit is synchronized to a common clock. A first relationship is calculated between the common clock and a playout fifo buffer read pointer, and a second relationship is calculated between the common clock and a capture FIFO buffer write pointer. For each sample in the playout time domain a corresponding sample in the samples from said computational unit is found and sent to the playout FIFO buffer. For each sample in the common clock time domain the corresponding sample in the capture time domain is found and sent to the computational unit.07-23-2009
20130121497System and Method for Acoustic Echo Cancellation Using Spectral Decomposition - A method and apparatus for canceling an echo in audio communication is disclosed. The method comprises receiving an audio signal from a network and subsequently detecting a mixture audio signal comprising a target audio signal and an echo audio signal, the echo signal corresponding to the received audio signal. The method then comprises estimating the target audio signal by determining magnitude spectrograms for the mixture and received audio signals respectively, estimating a magnitude spectrogram of the target audio signal dependent on those of the mixture and received audio signal, and generating an output audio signal that estimates the target audio signal, the output audio signal being dependent on the estimated magnitude spectrogram.05-16-2013
20130121498NOISE REDUCTION USING MICROPHONE ARRAY ORIENTATION INFORMATION - A handheld device includes: an orientation sensor; an audio processor connected to the orientation sensor and adapted to receive orientation information from the orientation sensor; and a plurality of microphones through which audio content is captured, wherein the audio processor modifies the noise reduction algorithm applied to the audio content captured based, at least in part, on the orientation information.05-16-2013
20090245528METHOD FOR REDUCING ECHO AND RELATED ECHO REDUCING DEVICE AND VOICE APPARATUS THEREOF - A method for reducing echo includes detecting whether an output sound volume is greater than a threshold value, and setting an input sensitivity from a first designated sensitivity value to a second designated sensitivity value when the output sound volume is detected to be greater than the threshold value. The method further includes detecting whether an interrupt signal is received, determining whether the interrupt signal is triggered by detecting that the output sound volume is greater than the threshold value when receiving the interrupt signal, detecting whether the input sensitivity is the second designated sensitivity value when determining that the interrupt signal is triggered by detecting that the output sound volume is greater than the threshold value, and setting the input sensitivity as the second designated sensitivity value when detecting that the input sensitivity is not the second designated sensitivity value.10-01-2009
20090252343INTEGRATED LATENCY DETECTION AND ECHO CANCELLATION - In an audio system having a microphone, a speaker coupled to a source of audio output, and an echo canceller coupled to the speaker and microphone, latency between the source of audio output and the speaker may be compensated in echo cancellation performed by the echo canceller. The echo canceller may use a reference signal derived from a signal from the source of audio output in echo cancellation. The latency may be compensated by measuring the latency between the signal from the source of audio output and the speaker, determining a delay amount from the latency, delaying the reference signal by the delay amount to produce a delayed reference signal, and using the delayed reference signal as the reference signal in the echo canceller.10-08-2009
20120195438Echo suppression for wireless handsets and headsets - The enhancements provided herein are designed to allow an acoustic echo suppressor algorithm to operate with significant echo path delay between an audio block R08-02-2012
20100150364Method for Determining a Time Delay for Time Delay Compensation - The invention provides a computer-implemented method for determining a time delay for time delay compensation of a microphone signal from a microphone array in a beamformer arrangement. For a given time, an instantaneous estimate of a position of a wanted sound source and/or of a direction of arrival of a signal originating from the wanted sound source is determined. The computer system then determines whether the instantaneous estimate deviates from a preset estimate of a position of the wanted sound source and/or of a direction of arrival of a signal originating from the wanted sound source according to a predetermined criterion. The predetermined criterion comprises a check whether the instantaneous estimate deviates from the preset estimate by at least a predetermined deviation threshold. If the predetermined criterion is fulfilled, the instantaneous estimate for the given time is set by the computer system as the preset estimate, and the computer system determines the time delay for time delay compensation of the microphone signal based on the instantaneous estimate.06-17-2010
20120140939METHOD AND DEVICE FOR CANCELLING ACOUSTIC ECHO - An acoustic echo cancellation device for generating a pseudo echo signal by filtering an input remote speaker signal based on a plurality of adaptive filters and controlling the adaptive filters to filter the same based on a filter coefficient. The acoustic echo cancellation device generates an error signal by subtracting the pseudo echo signal from a nearby speaker signal, determines a convergence state of the filter coefficient based on the error signal, and sets at least one filter coefficient with a previously used value to stop the operation for calculating new values for the corresponding filter coefficients when the filter coefficient is determined to be converged.06-07-2012
20100189274DEVICE FOR AND A METHOD OF PROCESSING AUDIO SIGNALS - A method is provided which is suitable to cope with non-linear echo paths during acoustic echo cancellation in speakerphones. Non-linear paths occur particularly in hands-free operation of, e.g., a mobile phone, due to driving the amplifier and loudspeaker in the non-linear range. The idea is to combine the commonly known one microphone approach of linear acoustic echo cancellation using an adaptive filter and a post-processor together with a multiple microphone approach using beam forming which separately removes the non-linear part of the echo.07-29-2010
20110110526ACOUSTIC ECHO CANCELLER AND ACOUSTIC ECHO CANCELLATION METHOD - An adaptive filter generates a pseudo echo sound signal based on a sound emission sound signal. An adder subtracts the pseudo echo sound signal from a low band component of a collected sound signal, thereby generating a sound signal with a first-adjusted low band component. An echo spectrum estimation section estimates and calculates a frequency spectrum of a reverberation echo this time from a spectrum of the pseudo echo sound signal this time, a frequency spectrum of the preceding reverberation echo, and an update coefficient based on an audio environment. An adder subtracts the frequency spectrum of the reverberation echo and the frequency spectrum of stationary noise from a spectrum of the sound signal with the first-adjusted low band component.05-12-2011
20090046866APPARATUS CAPABLE OF PERFORMING ACOUSTIC ECHO CANCELLATION AND A METHOD THEREOF - An apparatus capable of performing acoustic echo cancellation and a method thereof are provided. The apparatus comprises a mapping matrix, first and second speakers, first and second microphones, a reference generator, and a multi-channel acoustic echo canceller. The mapping matrix generates an output signal according to the first and second far end signals. The first and second speakers, coupled to the mapping matrix, play the output signal. The first and second microphones receive the first and second echo signals that are acoustically coupled from the first and second speakers to the first and second microphones, wherein the first and second echo signals are correlated to the output signal. The reference generator generates a reference signal linearly correlated to the output signal according to the first and second far end signals. The multi-channel acoustic echo canceller, coupled to the reference generator and the first and second microphones, filters the reference signal to generate the first and second filtered signals to be indicative of the estimated echo signals at the first and second microphones, subtracts the first filtered signal from the first echo signal to generate a first error signal, and subtracts the second filtered signal from the second echo signal to generate a second error signal, and then transmits the first and second error signals to a far end terminal.02-19-2009
20100189275PASSENGER COMPARTMENT COMMUNICATION SYSTEM - A communication system for a passenger compartment includes at least two microphone arrays arranged within first and second regions, respectively, in the passenger compartment, and at least two loudspeakers and a signal processor connected to the microphone arrays and to the loudspeaker. Each microphone array has at least two microphones and provides an audio signal. Each loudspeaker is located within a different one of the first and the second regions. The signal processor processes the audio signal from the microphone array within the first region and provides the processed audio signal to the loudspeaker located within the second region.07-29-2010
20100150363Method for testing echo cancellers - The performance of an echo canceller is assessed using a) a test signal launched from originating test equipment and b) a simulated echo of the test signal launched from terminating test equipment. The launch of the simulated echo signal is timed in such a way that it arrives at the tandem echo canceller(s) at a point in time relative to the arrival of the test signal thereat that the tandem echo canceller(s) is (are) not able to cancel the simulated echo signal. The latter thus arrives uncanceled at the target echo canceller. The launch of the simulated echo signal is further timed in such a way that it arrives at the target echo canceller at a point in time relative to the arrival of the test signal thereat that the target echo canceller IS able to cancel the simulated echo signal. As a result, any residual echo received at the originating test equipment is a measure of the performance of the target echo canceller exclusive of the performance of the tandem echo canceller(s).06-17-2010
20090316923MULTICHANNEL ACOUSTIC ECHO REDUCTION - A multichannel acoustic echo reduction system is described herein. The system includes an acoustic echo canceller (AEC) component having a fixed filter for each respective combination of loudspeaker and microphone signals and having an adaptive filter for each microphone signal. For each microphone signal, the AEC component modifies the microphone signal to reduce contributions from the outputs of the loudspeakers based at least in part on the respective adaptive filter associated with the microphone signal and the set of fixed filters associated with the respective microphone signal.12-24-2009
20100296663System and Method for the Application on an LMS Method to Updating an Echo Canceller in an ADSL Modem - An echo cancellation device relies on the known characteristics of the sync frame to monitor, update in an off-line fashion and determine the accuracy of an echo canceller in, for example, a modem, such as an ADSL modem. Specifically, time domain samples are read from the transmit (Tx) and receive (Rx) paths of the modem. These samples are stored in memory. When the sync frame has received a predetermined number of the same Tx samples and Rx samples, the samples are stored. Running averages, over the sync frames, of the TX and RX samples are maintained. These averages are subtracted from a sync frame of samples, to allow LMS updating of the echo canceller taps, free of extraneous signals. Updating, i.e., tracking of changes in the echo channel, is done for the echo canceller in an off-line fashion. The coefficients for the in-line version are updated, while the off-line version is updated over several sync frames. Periodically, the performance of the off-line version is compared with the in-line version. The coefficients of the in-line version are replaced by those of the off-line version only if it is determined the off-line version, which is tracking echo channel changes, has better performance. After replacement of the in-line coefficients, the off-line tracking is continued in the off-line version.11-25-2010
20090067637Echo control retrofit - The present invention provides an echo control retrofit apparatus and method that advantageously reduces echo when communicating over packet-switched networks. An echo control retrofit apparatus, including an echo control circuit, is operably coupled between a headset or handset device and an audio source. The echo control circuit receives a sound signal from the audio source and a transmit signal from the headset or handset device and provides an adjusted sound signal to the audio source. Advantageously, a variety of existing headsets and handsets may be used in accordance with the present invention to provide reduced caller echo without the need to purchase new headsets or handsets.03-12-2009
20100183163SOUND SIGNAL PROCESSOR AND DELAY TIME SETTING METHOD - An echo canceller formed of an adaptive filter is designed such that even under a condition where a system transmission delay is undefined, an appropriate delay time can be set in a delay circuit that absorbs a system delay, and that an effective echo cancellation effect can always be achieved. A time difference of a transmission path until a reproduction audio signal input to the delay circuit is input as a processing target signal of an adaptive filter system through a space between a speaker and a microphone is determined, and the delay time corresponding to this time difference is set in the delay circuit. At this time, the speaker and the microphone are placed so that the distance therebetween is small, and the delay time of the delay circuit is set to 0. Thus, the determined time difference indicates a system transmission delay in the above transmission path. That is, an accurate delay time corresponding to the system transmission delay can be set in the delay circuit.07-22-2010
20110019832SOUND PROCESSOR, SOUND PROCESSING METHOD AND RECORDING MEDIUM STORING SOUND PROCESSING PROGRAM - A sound processor includes a conversion unit converts a reference sound signal corresponding to a base of sound to be output and an observation sound signal based on each of sound signals output by a plurality of sound receiving units into frequency components, an echo suppression unit estimates echo derived from sound based on a converted reference sound signal and suppressing the estimated echo in a converted observation sound signal, a noise suppression unit estimates noise based on an arrival direction of sound and suppressing the estimated noise in the converted observation sound signal and an integrating process unit suppresses, with respect to each frequency component, echo and noise in the converted sound signal based on a observation sound signal obtained after echo suppression and a observation sound signal obtained after noise suppression.01-27-2011
20110019833APPARATUS AND METHOD FOR COMPUTING FILTER COEFFICIENTS FOR ECHO SUPPRESSION - A preferred embodiment of an apparatus for computing filter coefficients for an adaptive filter for filtering a microphone signal so as to suppress an echo due to a loudspeaker signal includes an extractor for extracting a stationary component signal or a non-stationary component signal from the loudspeaker signal or from a signal derived from the loudspeaker signal, and a computer for computing the filter coefficients for the adaptive filter on the basis of the extracted stationary component signal or the extracted non-stationary component signal.01-27-2011
20110019831Echo Suppression Method and Apparatus Thereof - In an echo suppression apparatus, an adaptive filter estimates an echo path of a near end, and generates a pseudo echo signal of a reception signal received from a far end. A subtractor subtracts the pseudo echo signal from a near-end signal including an echo signal of the reception signal, a near-end sound and a background noise, thereby generating an echo-canceled signal. A background noise estimation unit estimates a spectrum of the background noise. A non-linear processing unit performs spectrum subtraction of the estimated spectrum of the background noise from the spectrum of the echo-canceled signal, and controls a gain of the spectrum of the echo-canceled signal in response to the result of the spectrum subtraction, thereby obtaining a spectrum of a transmission signal transmitted to the far end. A threshold calculation unit calculates a threshold value used to determine presence or absence of the residual echo in the echo-canceled signal. The non-linear processing unit compares the result of the spectrum subtraction with the threshold value, then controls the spectrum of the echo-canceled signal with a high gain in case that the result of the spectrum subtraction is higher than the threshold value, and with a low gain in case that the result of the spectrum subtraction is not higher than the threshold value.01-27-2011
20110044462SIGNAL ENHANCEMENT DEVICE, METHOD THEREOF, PROGRAM, AND RECORDING MEDIUM - The initial values of parameter estimates are set, including reverberation parameter estimates, which includes a regression coefficient used in a linear convolutional operation for calculating an estimated value of reverberation included in an observed signal, source parameter estimates, which includes estimated values of a linear prediction coefficient and a prediction residual power that identify the power spectrum of a source signal, and noise parameter estimates, which include noise power spectrum estimates. Then, the maximum likelihood estimation is used to alternately repeat processing for updating at least one of the reverberation parameter estimates and the noise parameter estimates and processing for updating the source parameter estimates until a predetermined termination condition is satisfied.02-24-2011
20110116644SIMULATED BACKGROUND NOISE ENABLED ECHO CANCELLER - An apparatus may include a noise estimation unit configured to determine a noise spectrum associated with a noise signal, and generate a filter based on the determined noise spectrum. The apparatus may also include a noise synthesis unit configured to generate a colored noise using the filter generated by the noise estimation unit. The apparatus may be incorporated in an echo canceller.05-19-2011
20130156210TRAINING AN ECHO CANCELLER IN SEVERE NOISE - An apparatus includes a non-adaptive filter, an adaptive filter, and a controller. The non-adaptive filter may have non-adaptive filter coefficients and be configured to develop a non-adaptive error signal as a function of the non-adaptive filter coefficients. The adaptive filter may have adaptive filter coefficients and be configured to develop an adaptive error signal as a function of the adaptive filter coefficients. The controller may be configured to monitor a quality of the non-adaptive and adaptive error signals and perform one or more of a full coefficient update, a partial coefficient update and a fractional coefficient update of the non-adaptive filter coefficients based on a comparison of the quality of the adaptive error signal to a determined current best-attained performance measurement.06-20-2013
20090214048HARMONIC DISTORTION RESIDUAL ECHO SUPPRESSION - Harmonic distortion residual echo suppression (HDRES) technique embodiments are presented which act to suppress the residual echo remaining after a near-end microphone signal has undergone AEC, including harmonic distortion in the signal that was caused by the speaker audio signal playback. In general, an AEC module is employed which suppresses some parts of the speaker audio signal found in a near-end microphone signal and generates an AEC output signal. A HDRES module then inputs the AEC output signal and the speaker audio signal, and suppresses at least a portion of a residual part of the speaker audio signal that was left unsuppressed by the AEC module. This includes at least a portion of the harmonic distortion exhibited in the AEC output signal.08-27-2009
20100226503ECHO CANCELLER - An echo canceller capable of suppressing an echo more effectively than the case of performing filter processing by a signal of a fixed-point format while suppressing an increase in cost is provided. An echo canceller 09-09-2010
20090052684AUDIO CONFERENCING APPARATUS - Microphones arranged in an array shape along a longitudinal direction are respectively formed in both the longitudinal side surfaces of a housing 02-26-2009
20100054489DEREVERBERATION SYSTEM AND DEREVERBERATION METHOD - Provided is a dereverberation system or the like which copes with an arbitrary condition flexibly and is capable of recognizing a sound or a sound source signal. According to the dereverberation system, an inverse filter (h) is set by using a pseudo-inverse matrix (R03-04-2010
20110176688SIGNAL PROCESSING METHOD, SIGNAL PROCESSING DEVICE, AND SIGNAL PROCESSING PROGRAM - Provided is a signal processing method which receives a plurality of reception signals and subtracts pseudo-echoes generated by a plurality of adaptive filters which input the reception signals, from a plurality of echoes generated by the reception signals, thereby reducing the echoes. The method delays two or more of the reception signals so as to generate delayed reception signals and inputs the reception signals and the delayed reception signals to the adaptive filters so as to generate pseudo-echoes.07-21-2011
20090028354Echo Canceller Employing Dual-H Architecture Having Split Adaptive Gain Settings - An echo canceller circuit is set forth. The echo canceller circuit includes a digital filter having adaptive tap coefficients to simulate an echo response occurring during a call. The adaptive tap coefficients are updated during the call using a Means Squares process. A tap energy detector is also employed. The tap energy detector identifies and divides groups of taps having high energy from groups of taps having low energy. The high energy tap groups are smaller in number than the low energy tap groups. The high energy tap groups are adapted separately from the low energy tap groups using the Least Squares process. Still further, the high energy tap groups may be adapted using an adaptive gain constant a while the low energy tap groups are adapted using an adaptive gain constant a′, wherein a>a′.01-29-2009
20100260344Method and Arrangement for Echo Cancellation of Voice Signals - A method and arrangement for cancelling echoes in a communication terminal (10-14-2010
20110211706SOUND EMISSION AND COLLECTION DEVICE AND SOUND EMISSION AND COLLECTION METHOD - Provided is a sound emission and collection device capable of estimating the azimuth of a sound source (such as a main utterer) precisely without any processing load. The sound emission and collection device (09-01-2011
20080267420Methods and systems for reducing acoustic echoes in multichannel audio-communication systems - Various embodiments of the present invention are directed to adaptive real-time, acoustic echo cancellation methods and systems. One method embodiment of the present invention is directed to reducing acoustic echoes in microphone-digital signals transmitted from a first location to a second location. The first location includes a plurality of loudspeakers and microphones, each microphone produces one of the microphone-digital signals including sounds produced at the first location and acoustic echoes produced by the loudspeakers. The method includes determining approximate impulse responses, each of which corresponds to an echo path between the microphones and the loudspeakers. The method includes determining a plurality of approximate acoustic echoes, each approximate acoustic echo corresponds to convolving a digital signal played by one of the loudspeakers with a number of the approximate impulse responses. The acoustic echo in at least one of the microphone-digital signals is reduced based on the corresponding approximate acoustic echo.10-30-2008
20080205661SYSTEM AND METHOD FOR CANCELLING ECHO - A system and a method for canceling an echo is disclosed. In accordance with the system and the method, a plurality of independently and variably delayed adaptive algorithm blocks are selectively applied to a delayed feedback signal to generate a plurality of echo components in parallel, thereby canceling the echo component from an input signal.08-28-2008
20110255702SIGNAL DEREVERBERATION USING ENVIRONMENT INFORMATION - An audio processing system includes an audio processing device and an external device, the audio processing device having a signal processing unit adapted for running an algorithm for processing an input signal representing an acoustic signal from the environment of the user and providing a processed output signal. The external device includes in an information signal a measure, characteristic of the reverberation of the room or location where the audio processing device is located, and the audio processing device is adapted to extract the measure of the reverberation from the information signal and use the measure as an input to an algorithm that includes a directional algorithm for providing a directional characteristic of the input signal.10-20-2011
20100246844Method for Determining a Signal Component for Reducing Noise in an Input Signal - The invention provides a method for determining a signal component for reducing noise in an input signal, which comprises a noise component, comprising the steps of: estimating the noise component in the input signal, estimating a reverberation component in the noise component, and removing the estimated reverberation component from the estimated noise component to obtain a modified estimate of the noise component.09-30-2010
20110255703DETERMINING AN ACOUSTIC COUPLING BETWEEN A FAR-END TALKER SIGNAL AND A COMBINED SIGNAL - The present invention provides an improved determination of an acoustic coupling between a loudspeaker (10-20-2011
20100166200Feedback Elimination Method and Apparatus - A method and apparatus for detecting a singing frequency in a signal processing system using two neural-networks is disclosed. The first one (a hit neural network) monitors the maximum spectral peak FFT bin as it changes with time. The second one (change neural network) monitors the monotonic increasing behavior. The inputs to the neural-networks are the maximum spectral magnitude bin and its rate of change in time. The output is an indication whether howling is likely to occur and the corresponding singing frequency. Once the singing frequency is identified, it can be suppressed using any one of many available techniques such as notch filters. Several improvements of the base method or apparatus are also disclosed, where additional neural networks are used to detect more than one singing frequency.07-01-2010
20100166199ACOUSTIC ECHO REDUCTION CIRCUIT FOR A "HANDS-FREE" DEVICE USABLE WITH A CELL PHONE - The device comprises: a circuit for picking up acoustic signals with the microphone (07-01-2010
20100067712Echo Cancelling Device, Signal Processing Device and Method Thereof, and Program - An echo cancelling device includes a filter-coefficient polarity inverter configured to invert the polarity of a filter coefficient at intervals of a predetermined frame length, an adaptive filter configured to estimate a signal to be inputted from an unknown system by multiplying a signal to be outputted from a speaker by the filter coefficient, and generate the resultant estimated signal, a subtracter configured to calculate an error signal from an input signal from a microphone and the estimated signal, and an error-signal polarity inverter configured to invert the polarity of the error signal in synchronization with the inversion of the polarity of the filter coefficient at intervals of the predetermined frame length. The adaptive filter updates the filter coefficient on the basis of the error signal by using binary fixed-point arithmetic, and therein, performing a truncation operation.03-18-2010
20110135105ECHO CANCELLER - An adaptive filter unit 06-09-2011
20120148059Controlling Audio Signals - Method, user terminal and computer program product for controlling audio signals at the user device during a communication session between the user device and a remote node, in which a primary audio signal is received at audio input means of the user device for transmission to the remote node in the communication session. It is determined whether the user device is operating in (i) a first mode in which secondary audio signals output from the user device are likely to disturb the primary audio signal received at the audio input means, or (ii) a second mode in which secondary audio signals output from the user device are not likely to disturb the primary audio signal received at the audio input means. In dependence upon determining that the user device is operating in the first mode, the secondary audio signals are selectively suppressed from being output from the user device during the communication session, such that when the user device is operating in the first mode said secondary audio signals do not disturb the primary audio signal received at the audio input means for transmission to the remote node in the communication session.06-14-2012
20100215184Method for Determining a Set of Filter Coefficients for an Acoustic Echo Compensator - The invention provides a method for determining a set of filter coefficients for an acoustic echo compensator in a beamformer arrangement. The acoustic echo compensator compensates for echoes within the beamformed signal. A plurality of sets of filter coefficients for the acoustic echo compensator is provided. Each set of filter coefficients corresponds to one of a predetermined number of steering directions of the beamformer arrangement. The predetermined number of steering directions is equal to or greater than the number of microphones in the microphone array. For a current steering direction, a current set of filter coefficients for the acoustic echo compensator is determined based on the provided sets of filter coefficients.08-26-2010
20130010976Efficient Audio Signal Processing in the Sub-Band Regime - A signal processing system enhances an audio signal. The audio signal is divided into audio sub-band signals. Some audio sub-band signals are excised. Other audio sub-band signals are processed to obtain enhanced audio sub-band signals. At least a portion of the excised audio sub-band signals are reconstructed. The reconstructed audio sub-band signals are synthesized with the enhanced audio sub-band signals to form an enhanced audio signal.01-10-2013
20090245527LINEAR FULL DUPLEX SYSTEM AND METHOD FOR ACOUSTIC ECHO CANCELLATION - A linear full duplex system and method for acoustic echo cancellation is disclosed. In one embodiment, a method includes calculating a residual echo after subtraction of an echo estimate from a near end signal associated with a communication, refining a far end and a residual signal associated with the communication, updating, based on the far end signal, the echo estimate of an echo associated with the communication, subtracting the echo from the near end signal based on the echo estimate to cancel the echo associated with the communication, updating, based on the refined far end and refined residual signal, the adaptive filter module used for echo estimation, and detecting a steady state and, during the steady state, dynamically detecting internal substates and switching between the internal substates and detecting and managing double talk associated with the communication.10-01-2009
20120250871Nonlinear Echo Suppression - Presented is a method and associated system for suppression of linear and nonlinear echo. The method includes dividing an input signal into several frequency bands in each of a several of time frames. The input signal may include an echo signal. The method further includes multiplying the input signal in each of the several frequency bands by a corresponding echo suppression signal. Calculating the corresponding echo suppression signal may include estimating a power of the echo signal in a particular frequency band as a sum of several component echo powers, each of the several component echo powers due to an excitation from a far-end signal in a corresponding one of the several frequency bands. Calculating the corresponding echo suppression signal may further include subtracting the power of the echo signal in the particular frequency band from a power of the input signal in the particular frequency band.10-04-2012
20120045069Dynamic Audibility Enhancement - A method of enhancing an audio signal includes the steps of: a) receiving a primary audio input signal, b) receiving a detected audio signal which comprises: A) an echo component derived from play-out of the primary audio input signal and B) a noise component, and c) estimating from the primary audio input signal and the detected audio signal: 1) a set of frequency-specific lower bound gains, such that each frequency-specific lower bound gain, when applied to a respective frequency of the primary audio input signal, would cause the noise component to just mask the echo component at that respective frequency and 2) a set of frequency-specific upper bound gains, such that, each frequency-specific upper bound gain, when applied to a respective frequency of the primary audio input signal, would cause the echo component to just mask the noise component, at that respective frequency; d) estimating a sat of frequency-specific gains in such a way that each frequency-specific gain falls between the respective frequency-specific lower bound gain and respective frequency-specific upper bound gain; and e) applying the frequency-specific gains to the primary audio input signal.02-23-2012
20120207315AUDIO PROCESSING APPARATUS AND METHOD OF CONTROLLING THE AUDIO PROCESSING APPARATUS - An audio processing apparatus includes first and second audio pickup units. The second audio pickup unit includes an audio resistor provided to cover a sound receiving portion to suppress external wind introduction while passing an external audio. A first filter attenuates a signal having a frequency lower than a first cutoff frequency of the output signal of a first A/D converter. A second filter attenuates a signal having a frequency higher than a second cutoff frequency of the output signal of a second A/D converter. A third filter is provided between the first audio pickup unit and the first A/D converter to attenuate a signal having a frequency lower than a third cutoff frequency for suppressing the wind noise.08-16-2012
20120114129MIXER WITH ADAPTIVE POST-FILTERING - A noise reduction system includes multiple transducers that generate time domain signals. A transforming device transforms the time domain signals into frequency domain signals. A signal mixing device mixes the frequency domain signals according to a mixing ratio. Frequency domain signals are rotated in phase to generate phase rotated signals. A post-processing device attenuates portions of the output based on coherency levels of the signals.05-10-2012
20120155665Echo Canceller With Adaptive Non-Linearity - An echo canceller (06-21-2012
20120027218Multi-Microphone Robust Noise Suppression - A robust noise reduction system may concurrently reduce noise and echo components in an acoustic signal while limiting the level of speech distortion. The system may receive acoustic signals from two or more microphones in a close-talk, hand-held or other configuration. The received acoustic signals are transformed to cochlea domain sub-band signals and echo and noise components may be subtracted from the sub-band signals. Features in the acoustic sub-band signals are identified and used to generate a multiplicative mask. The multiplicative mask is applied to the noise subtracted sub-band signals and the sub-band signals are reconstructed in the time domain.02-02-2012
20120106749Microphone Non-Uniformity Compensation System - A microphone compensation system responds to changes in the characteristics of individual microphones in an array of microphones. The microphone compensation system provides a communication system with consistent performance despite microphone aging, widely varying environmental conditions, and other factors that alter the characteristics of the microphones. Furthermore, lengthy, complex, and costly measurement and analysis phases for determining initial settings for filters in the communication system are eliminated.05-03-2012
20120063609ACOUSTIC MULTI-CHANNEL CANCELLATION - A multi-channel acoustic echo canceller arrangement comprises a microphone (03-15-2012
20120063608SYSTEM FOR EXTRACTION OF REVERBERANT CONTENT OF AN AUDIO SIGNAL - A reverberant characteristic of an acoustic space is superimposed on an audio signal that is received by an apparatus. The apparatus decomposes the audio signal into an estimated original dry signal component and an estimated reverberant characteristic of the acoustic space. Estimation of the original dry signal component and the reverberant characteristic of the acoustic space is based on determination of an estimated impulse response of the acoustic space from the received audio signal. Once the audio signal is decomposed, the estimated original dry signal component and the estimated reverberant characteristic of the acoustic space may be independently modified by the apparatus. The modified or unmodified estimated original dry signal component and estimated reverberant characteristic of the acoustic space may be combined by the apparatus to produce one or more adjusted frequency spectra.03-15-2012
20100092003INTEGRATING ACOUSTIC ECHO CANCELLATION AS A SUBSYSTEM INTO AN EXISTING VIDEOCONFERENCE AND TELEPRESENCE SYSTEM - The present invention is embodied in a computer-readable program in a computer-readable medium for upgrading a video conference system, the computer-readable program comprising acoustic echo canceling control software having an application programming interface. The acoustic echo canceling control software is implemented on a computer system that operates the video conference system and macros are configured to couple the acoustic echo canceling control software to hardware components of the video conference system and to interface with the application programming interface. The macros are user configurable for providing real time adjustments of echo canceling runtime parameters of the hardware components during a video conference session.04-15-2010
20120163612Communication System - An echo component of a first signal received at an audio input device is removed. A second signal is output from an audio output device. The echo component in the first signal is the result of the second signal traversing an echo path. The characteristics of the first and second signals are compared, and if the first signal only comprises the echo, an estimate of the echo path is determined by comparing the first and second signals. The echo path estimate is applied to the first signal to determine an equalised first signal, which is is compared with the second signal to determine an estimate of the echo component. The echo component from the first signal is removed in dependence on the estimate of the echo component.06-28-2012
20120128168METHOD AND APPARATUS FOR NOISE AND ECHO CANCELLATION FOR TWO MICROPHONE SYSTEM SUBJECT TO CROSS-TALK - A method and apparatus for joint noise and echo cancellation of a two microphone system subject to cross-talk. The method includes estimating the reference output by removing the cross-talk and the estimated echo from the reference channel, when an echo is detected in the reference echo signal, adapting filters H05-24-2012
20100208908ECHO SUPRESSING METHOD AND APPARATUS - The coefficient generating section receives a first signal which is the output signal of the microphone of a signal generated by subtracting the output signal of a linear echo canceller from the output signal of the microphone and a second signal which is the output signal of the linear echo canceller. The coefficient generating section detects the minimum value of the variation with time of the ratio of the amplitude of the first signal to that of the second signal and outputs the value of constant times the detected minimum value as a crosstalk coefficient indicating the degree of crosstalk of the echo. The converting section corrects the first signal according to the crosstalk coefficient and the second signal to generate a near-end signal which is the resultant signal of when the echo is removed from the first signal and outputs the near-end signal to an output terminal.08-19-2010
20080298602SYSTEM FOR PROCESSING MICROPHONE SIGNALS TO PROVIDE AN OUTPUT SIGNAL WITH REDUCED INTERFERENCE - A system reduces noise or other external signals that may affect communication. A device converts sound from two or more microphones into an operational signal. Based on one or both signals, a beamformer generates an intermediate signal. Reflected or other undesired signals may be estimated or measured by an echo canceller. Interference may be measured or estimated by processing the echo-reduced signal or estimate by a blocking matrix. An interference canceller may reduce the interference that may modify or disrupt a signal based on the output of the blocking matrix and the intermediate signal.12-04-2008
20080298601Double Talk Detection Method Based On Spectral Acoustic Properties - A method of detecting double talk condition in hands free communication devices is disclosed. In general, the method in accordance with the teachings of this invention detects double talk conditions based on inherent frequency response differences between the transducers used and acoustical effect on the spectrum of the returned echo signal. An input signal from a far-end talker and an input signal from the output from an echo canceler are received by the detector. K spectral subbands are created for each input signal. From this K subbands q subbands are selected based on inherent frequency differences between the far-end transducer and a near-end transducer. The spectral echo residual power is estimated at each subband. The estimated spectral echo power and the output signal from the echo canceler for a selected subband are compared to a predetermined threshold. Based on this comparison, it is determined whether double talk conditions exist based on the comparison.12-04-2008
20110268287LOUDSPEAKER SYSTEM AND SOUND EMISSION AND COLLECTION METHOD - A loudspeaker system with a high degree of versatility, which, even when a microphone or a person speaking moves, can adequately response to the movement is provided. A plurality of linkage terminals 11-03-2011
20110158418DEREVERBERATION AND NOISE REDUCTION METHOD FOR MICROPHONE ARRAY AND APPARATUS USING THE SAME - A dereverberation and noise reduction method adapted for a microphone array and an apparatus using the same are proposed. The microphone array receives a plurality of audio signals from an audio source. The dereverberation and noise reduction method includes the following steps. The received audio signals are processed by a beamforming processing, and a first audio signal is generated. Besides, the received audio signals are processed by a suppression processing, and a suppression audio vector is generated. Further, suppression audio vector is processed by an adaptive filtering processing, and a second audio signal is generated. In addition, the second audio signal is subtracted from the first audio signal to acquire an audio output signal, where parameters of the adaptive filtering processing are adjusted according to a feedback of the audio output signal.06-30-2011
20080247559ELECTRICITY ECHO CANCELLATION DEVICE AND METHOD - An electricity echo cancellation device applied at a terminal includes: an input buffer memory module, a network echo delay computation module and an adaptive filtering module. The adaptive filtering module includes an adaptive filter, a subtracter and a dual-ended voice detection module. An electricity echo cancellation method includes: calculating a network echo delay according to relevant information of an RTCP packet transmitted from the network; and dynamically adjusting a terminal input signal to be adaptively filtered according to the network echo delay. The present invention ensures the electricity echo cancellation effect at the final user end on the whole, and improves the effectiveness of electricity echo cancellation. Meanwhile method of the present invention can be realized with software, thus avoiding influences of hardware memory restricts on the echo cancellation effect. In addition, the present invention only needs a single-point deployment, and thus the cost is saved.10-09-2008
20080247558Robust and Efficient Frequency-Domain Decorrelation Method - An audio signal is processed by transforming the signal into a frequency domain representation having a plurality of frequency subbands. A decorrelated signal is derived from the frequency domain representation using a phase rotation.10-09-2008
20080247557Information Processing Apparatus and Program - According to one embodiment, a signal processing apparatus includes a speaker configured to output the received input signal on which a delay detection signal which has a frequency component of an inaudible frequency on a received input signal is superposed to an acoustic space, an extracting section configured to extract the delay detection signal from the sending input signal outputted from microphone configured to collect sound in the acoustic space a calculating section configured to calculate a delay time between the received input signal and an acoustic echo component contained in the sending input signal, a delay section configured to delay the received input signal by a time corresponding to the delay time and generate a delayed received input signal, and an echo suppression processing section configured to suppress the acoustic echo component contained in the sending input signal by use of the delayed received input signal.10-09-2008
20080226090Oscillation/Echo Canceller System - An oscillation/echo canceller system (09-18-2008
20130177162NOVEL PRE-PROCESS (AMPLITUDE DISTORTION) AND POST-PROCESS (PHASE SYNCHRONIZATION) FOR LINEAR AEC SYSTEM - An acoustic processing apparatus is provided. The apparatus includes a pre-processing component, a filter and a first signal processing component. The pre-processing component compensates a non-linearity of a reference signal to generate an input signal. The filter coupled to the pre-processing component, the filter executes filtering on the input signal to generate an output signal. The first signal processing component, coupled to the pre-processing component, the reference signal obtains a gain from the first signal processing component to generate a first signal, and the first signal processing component passes the gain to the pre-processing component.07-11-2013
20130129101MULTICHANNEL ACOUSTIC ECHO REDUCTION - A multichannel acoustic echo reduction system is described herein. The system includes an acoustic echo canceller (AEC) component having a fixed filter for each respective combination of loudspeaker and microphone signals and having an adaptive filter for each microphone signal. For each microphone signal, the AEC component modifies the microphone signal to reduce contributions from the outputs of the loudspeakers based at least in part on the respective adaptive filter associated with the microphone signal and the set of fixed filters associated with the respective microphone signal.05-23-2013
20130129100PROCESSING AUDIO SIGNALS - In an embodiment, a method of processing audio signals at a device includes receiving audio signals at a plurality of microphones of the device; processing at least one of the audio signals received by the plurality of microphones to generate a first characteristic; a beamformer applying beamformer coefficients to the received audio signals, thereby generating a beamformer output; processing the beamformer output to generate a second characteristic. An echo canceller is applied to the beamformer output, thereby suppressing, from the beamformer output, an echo resulting from audio signals output from an audio output. An operating parameter of the echo canceller is determined, using a relationship between the first and second characteristics.05-23-2013
20130142348Method and System for Bone Conduction Sound Propagation - A wearable ambient sound reduction system, the system may include: a microphone, adapted to detect an ambient sound signal; a processor adapted to generate an output signal in response to the ambient sound signal; wherein the output signal, when conveyed to a bone of the user, reduces an affect that an ambient sound signal has upon the user; wherein the microphone is coupled to the processor; and a bone conduction speaker, coupled to the processor, adapted to convey the output signal to a bone of a user.06-06-2013
20100278351Methods and systems for reducing acoustic echoes in multichannel communication systems by reducing the dimensionality of the space of impulse resopnses - Various embodiments of the present invention are directed to adaptive methods for reducing acoustic echoes in multichannel audio communication systems. Acoustic echo cancellation methods determine approximate impulse responses characterizing each echo path between loudspeakers and microphones within a room and improve performance based on previously determined impulse responses. In particular, the methods adapt to changes in the room by inferring approximate impulse responses that lie within a model of an impulse response space. Over time the method improves performance by evolving the model into a more accurate space from which to select subsequent approximate impulse responses.11-04-2010
20130156211WIDEBAND ACOUSTIC ECHO CANCELLATION APPARATUS WITH ADAPTIVE TAIL LENGTH IN EMBEDDED SYSTEM, AND WIDEBAND ACOUSTIC ECHO CANCELLATION METHOD - A wideband acoustic echo cancellation apparatus with an adaptive tail length in an embedded system, and a wideband acoustic echo cancellation method are provided, and the wideband acoustic echo cancellation apparatus may include a delay length calculating unit to calculate a delay length of an echo path, using a near-end signal and a far-end signal, an adaptive filter implementing unit to implement an adaptive filter based on the calculated delay length, using selected coefficients, and an error calculating unit to search for three intervals having a largest impulse response value from all intervals of a tail of the adaptive filter, and to calculate an error during an interval in which the selected coefficients are used.06-20-2013
20090028355Double-talk detector with accuracy and speed of detection improved and a method therefor - A double-talk detector finds an estimated power value of near end background noise based on a residual signal by a noise estimator; the average power of a transmitter input signal by a transmitter average power calculator; the average power of a receiver input signal by a receiver average power calculator; and an estimated echo path attenuation value through a predetermined echo path attenuation value estimating process based on the estimated power value of the near end background noise, the average power of the transmitter input signal and the average power of the receiver input signal by an attenuation value estimator. The double-talk detector detects a double-talk state based on the estimated echo path attenuation value, the average power of the transmitter input signal and the average power of the receiver input signal by a double-talk determiner to control update of the coefficient of an adaptive filter.01-29-2009
20100316228METHODS AND SYSTEMS FOR BLIND DEREVERBERATION - Various embodiments of the present invention are directed to methods for dereverberation of audio generated in a room. In one aspect, a method for dereverberating reverberant digital signals comprises transforming a reverberant digital signal from the time domain into Fourier domain signals using a computing device, each Fourier domain signal corresponding to a subband. For each subband of the Fourier domain signal, the method computes autoregressive model coefficients of the reverberation with the current and previous magnitudes of the Fourier digital signal, and inverse filters the magnitude of the Fourier domain signal using the computing device, based on the autoregressive model coefficients and previous magnitudes of the Fourier digital signal. The method includes inverse transforming the Fourier domain signals with filtered magnitudes into an approximate dereverberated digital signal.12-16-2010
20130156209OPTIMIZING AUDIO PROCESSING FUNCTIONS BY DYNAMICALLY COMPENSATING FOR VARIABLE DISTANCES BETWEEN SPEAKER(S) AND MICROPHONE(S) IN A MOBILE DEVICE - Mobile communication devices, having multiple speakers and/or microphones to perform a number of audio functions, for use with mobile devices, are provided. The microphones may be housed within the communication device housing. To compensate for the unwanted signal feedback between the speakers and microphones, acoustic echo cancellation may be implemented to determine the proper distance and relative location between the speakers and microphones. Acoustic echo cancellation removes the echo from voice communications to improve the quality of the sound. The removal of the unwanted signals captured by the microphones may be accomplished by characterizing the audio signal paths from the speakers to the microphones (speaker-to-microphone path distance profile), including the distance and relative location between the speakers and microphones. The optimal distance and relative location between the speakers and microphones is provided to the user to optimize performance.06-20-2013
20110311066Echo Cancellers and Echo Cancelling Methods - Methods and systems for updating the adaptive filter of an echo canceller. A method of updating the adaptive filter of an echo canceller in which an estimated echo is resolved from a received signal and then subtracted from an incoming echo-contaminated signal so as to produce a filtered output signal, includes: obtaining a corrected impulse response of an echo reconstruction filter (ERF); calculating specified decision measures usable to decide whether to prospectively apply the corrected ERF impulse response or a current ERF impulse response; determining whether application of the corrected ERF impulse response would result in improved echo cancellation; and updating the ERF to apply the corrected impulse response, when it is determined that the updating would result in a lower residual echo.12-22-2011
20130188797Over-Sampled Single-Sided Subband Echo Cancellation - A method of echo cancellation, particularly for use in high definition applications, splits an input signal and reference signal into M single-sided sub-band. The subbanded signals are downsampled at a downsampling rate N, where N≦M, adaptively filtered, and recombined to produce an output signal. The sub-bands are preferably oversampled such that N07-25-2013
20130188798REVERBERATION REDUCTION DEVICE AND REVERBERATION REDUCTION METHOD - A reverberation reduction device includes, a processor; and a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute, calculating reverberation characteristics in response to an impulse response of a path of a sound from an audio output unit to an audio input unit by determining the impulse response from a first audio signal and a second audio signal that represents a sound that the audio input unit has picked up from the first audio signal reproduced by the audio output unit, and estimating a distance from the audio input unit to a sound source in accordance with at least one of a volume and a frequency characteristic of a third audio signal that represents a sound that the audio input unit has picked up from a sound from the sound source; correcting the reverberation characteristics so that the reverberation characteristics.07-25-2013
20130188799AUDIO PROCESSING DEVICE AND AUDIO PROCESSING METHOD - An audio processing device includes a reverb property estimating unit that estimates a reverb property at each frequency on the basis of a first audio signal and a second audio signal representing sounds of the first audio signal output by an audio output unit and collected by an audio input unit, a gain calculating unit that determines an attenuating ratio for a component of the first audio signal at each frequency such that the larger the reverb property at the frequency is, the larger the attenuating ratio for the component at the frequency becomes, and a correcting unit that attenuates the first audio signal at the each frequency in accordance with the attenuating ratio determined for each frequency.07-25-2013
20120045070ACTIVE NOISE CONTROL DEVICE - The active noise control device includes: a signal obtaining section that obtains an electric signal relating to the predetermined sound; a control section that adjusts an amplitude and a phase of the electric signal obtained by the signal obtaining section; a vibrating section having a diaphragm and a vibrator, the vibrator vibrating in accordance with an output from the control section. Because a sound radiated from the diaphragm toward the first region is substantially in opposite phase to that toward the second region, the control section controls the vibrator so that the diaphragm generates a sound that attenuates the predetermined sound in the first region, and causes the predetermined sound to have a desired frequency characteristic in the second region.02-23-2012
20080304675Acoustic Echo Canceller - An acoustic echo cancellation device (12-11-2008
20130208905Temporal Interpolation Of Adjacent Spectra - Embodiments of the present invention exploit redundancy of succeeding FFT spectra and use this redundancy for computing interpolated temporal supporting points. An analysis filter bank converts overlapped sequences of an audio (ex. loudspeaker) signal from a time domain to a frequency domain to obtain a time series of short-time loudspeaker spectra. An interpolator temporally interpolates this time series. The interpolation is fed to an echo canceller, which computes an estimated echo spectrum. A microphone analysis filter bank converts overlapped sequences of an audio microphone signal from the time domain to the frequency domain to obtain a time series of short-time microphone spectra. The estimated echo spectrum is subtracted from the microphone spectrum. Further signal enhancement (filtration) may be applied. A synthesis filter bank converts the filtered microphone spectra to the time domain to generate an echo compensated audio microphone signal. Computational complexity of signal processing systems can, therefore, be reduced.08-15-2013

Patent applications in class DEREVERBERATORS