128 results about "Double-talk" patented technology

A signal processing device includes an adaptive filter (5), a noise estimation circuit (10), and a double talk detection circuit (81) and operates so that the double talk detection circuit (81) detects a double talk by using the estimated noise obtained by the noise estimation circuit (10). The signal processing device further includes noise estimation means and detects a double talk by using an estimated noise, a microphone signal, and pseudo-echo. An echo removal method and device detect a double talk by using a reliability coefficient expressed as continuous values between 0 and 1. By using continuous values instead of two values 0 and 1, it is possible to reduce the affect of a detection error.

A downlink activity and double talk probability detector and method for an echo canceler circuit (10) improves the stability of an echo canceler adaptive filter (300) and improves the attenuation of post-echo canceler uplink data (388). The echo canceler circuit (10) includes a downlink activity and double talk probability data generator (30) and an echo canceler stage (20). The downlink activity and double talk probability data generator (30) receives pre-echo canceler uplink data (40) and downlink data (50) and in response produces double talk probability data (60) and downlink activity data (70). The echo canceler stage (20) receives the downlink data (50), the pre-echo canceler uplink data (40), the double talk probability data (60) and the downlink activity data (70), and in response produces uplink data (80).

Disclosed is an apparatus for cancelling far endpoint echo signals in audio signals transmitted from a near endpoint to a far endpoint. In one embodiment, the apparatus includes a near endpoint analysis filter bank operable to divide a near endpoint signal into a plurality of near endpoint subband signals, a far endpoint analysis filter bank operable to divide a far endpoint signal into a plurality of far endpoint subband signals, and a background signal power estimator operable to determine background noise at the near end.

An echo canceller includes two parallel filters and a controller. The controller chooses the best of the two filters for the final echo cancellation. The filter coefficients are exchanged between the two filters constantly so that both filters retain performance all the time even if double-talk and echo path variations occur very closely in time. One filter is strongly robust and will not diverge during double-talk, and another filter is weakly robust and will converge rapidly during echo path variation.

A double talk activity detector (30) and method for an echo canceler circuit (10) improves the probability of detecting a double talk condition based on at least pre-echo canceler uplink data (40). The echo canceler circuit (10) includes a double talk activity probability data generator (30) and an echo canceler stage (20). The double talk activity probability data generator (30) receives pre-echo canceler uplink data (40) and in response produces double talk activity probability data (50). The echo canceler stage (20) is coupled to the double talk activity probability data generator (30) and receives downlink data (60), pre-echo canceler uplink data (40) and the double talk activity probability data (50) and in response produces attenuated uplink data (70).

An apparatus and method for echo cancellation is presented. The echo canceller comprises an adaptive filter that tracks the impulse response of the echo path and produces an estimate of the echo. Filter adaptation is controlled by a controller based on the rate of the far-end speech signal, the rate of the near-end signal, an acoustic loss measure, and a double talk hangover indicator. The controller may also comprise a step size adaptation unit for determining the adaptation step size of the adaptive filter. In addition, the controller may comprise a noise replacement unit, which controls replacement of the echo residual signal with comfort noise to ensure echo is completely rejected when only the far-end speaker is talking.

A method and apparatus for performing double-talk detection in an acoustic echo canceller in which a detection statistic is advantageously computed based on an estimate of a cross-correlation between the far-end signal and the return signal which has been normalized with use of an estimate of a covariance matrix of the far-end signal. The estimate of the cross-correlation between the far-end signal and the return signal may be further normalized with use of either an estimate of a variance of the return signal or an estimate of a covariance matrix of the return signal. In certain illustrative embodiments of the invention, one or more of these quantities may be estimated based on signal samples sampled over a predetermined time window. And in another illustrative embodiment of the present invention, the coefficients of the adaptive filter employed in the acoustic echo canceller itself are advantageously used to compute the detection statistic. These computations may be performed in either the time domain or the frequency domain. The detection statistic so computed is compared with a predetermined threshold, which threshold may be advantageously fixed at a value close to one, in order to determine whether or not double-talk has occurred.

The invention discloses a method and a device of echo elimination. The method comprises the following steps of: determining the energy of remote input signals and residual signals by a self-adapting filter according to the remote input signals in the last filtering treatment and the residual signals obtained in the last filtering treatment; determining filter coefficients used in the current filtering treatment by the self-adapting filter according to the filter coefficients used in the last filtering treatment, the remote input signals, the residual signals and the energy sum of the remote input signals and the residual signals; and executing the current filtering treatment by the self-adapting filter according to the determined current filter coefficients. The invention realizes the echo elimination in voice communication under the condition that double-talk detection is not carried out.

The present application provides an acoustic echo mitigation apparatus and method, an audio processing apparatus and a voice communication terminal. According to an embodiment, an acoustic echo mitigation apparatus is provided, including: an acoustic echo canceller for cancelling estimated acoustic echo from a microphone signal and outputting an error signal; a residual echo estimator for estimating residual echo power; and an acoustic echo suppressor for further suppressing residual echo and noise in the error signal based on the residual echo power and noise power. Here, the residual echo estimator is configured to be continuously adaptive to power change in the error signal. According to the embodiments of the present application, the acoustic echo mitigation apparatus and method can, at least, be well adaptive to the change of power of the error signal after the AEC processing, such as that caused by change of double-talk status, echo path properties, noise level and etc.

A method of suppressing an echo signal in a communication path such as acoustic coupling between a speaker and a microphone in a telephone device handset includes the steps of monitoring a transmitted signal supplied to the communication path to determine an attribute thereof; generating a leaky mask based on the determined attribute and an attribute of a received echo signal; and partially cancelling the received echo signal using the leaky mask.

This invention deals with an adaptive echo cancelling system for communication networks. The system includes an adaptive filter for acoustic echo cancellation that uses a combination of echo cancelling and gain control techniques. The main advantages of the combination of these approaches are good communication quality during double talk and easier control of the output echo level.

The invention provides a residual echo suppression method and system, and aims to solve the problem of initial-state echo leakage of an adaptive filter by estimating residual echo according to the relevance between a reference signal and a residual signal at the initial convergence stage of the adaptive filter. The method comprises the following steps: estimating the residual echo once by using estimated echo after the convergence of the adaptive filter; estimating the residual echo once by using the relevance between the reference signal and the residual signal; and estimating and calculating two residual echo suppression gains by using the two residual echoes, and weighting the two gains to obtain a total gain. Through adoption of the residual echo suppression method and system, the double-talk effect is effectively improved.

The invention discloses a double-talk detection and echo cancellation method based on zero-crossing rate, comprising the following steps: S1, zero-crossing rate calculation and double-talk monitoring: different echo cancellation strategies are adopted for double-talk and single-talk scenarios; S2, echo filter estimation and echo cancellation; there is difference between an echo signal collected by a microphone and a far-end signal because of room impulse response, and the echo component is eliminated from the signal collected by the microphone; and S3, recovery of a target speech harmonic structure. A harmonic structure analysis method is used to compensate for the missing harmonic components of near-end speech to further inhibit speech distortion. Compared with the traditional echo cancellation technology, double-end monitoring is realized based on the zero-crossing rate, and elimination of target speech is avoided. Based on the criterion of frequency-domain minimum mean square error, an echo cancellation filter converges rapidly. By adopting a frequency-domain parallel processing framework, the complexity is low. A speech distortion inhibition module is added, and the distortion degree of target speech is reduced.

The invention relates to a call state detection method and device. The method comprises the steps of obtaining a far end signal; superposing an ultrasonic signal on the far end signal to obtain a hybrid signal, and playing the hybrid signal; obtaining a near end signal collected by a microphone unit; determining a first signal segment in the hybrid signal and a second signal segment in the near end signal according to the ultrasonic signals; calculating a correlation value between the first signal segment and the second signal segment; and when the correlation value is smaller than a preset correlation value threshold, determining that a call state is a double-talk state. According to the scheme, the hybrid signal and the near end signal are aligned through the ultrasonic signal superposed in the far end signal and the ultrasonic signal contained in the near end signal collected by the microphone unit, and whether the call state is the double-talk state or not is judged through the correlation value between the aligned near end signal and hybrid signal, thereby improving the accuracy of detecting the double-talk state.

A method and apparatus for canceling an acoustic echo in a mobile terminal involving an acoustic echo canceller (AEC) for canceling an echo signal from a received far-end user's signal. Upon detecting double talk, a down-sampler lowpass-filters an output signal and down-samples the lowpass-filtered signal. The AEC estimates an echo signal using the far-end user's signal, and outputs a residual echo signal by canceling the estimated echo signal from the down-sampled signal. An up-sampler up-samples the residual echo signal by zero padding, and lowpass-filters the up-sampled signal.

Disclosed is an adaptive filter that prevents adaptation error from increasing in a state of double talk, without providing a double-talk detection circuit. In this adaptive filter, using input signal x[n] and error signal e[n], a tap coefficient setting section (202) calculates a numerator term of update coefficient Δw_n[i] in a delay circuit (301) and a multiplier (302), and calculates a normalized denominator term of update coefficient Δw_n[i] in a multiplier (303), a multiplier (304), an adder (305), an averaging circuit (306), and an adder (307). The tap coefficient setting section (202) divides the numerator term by the normalized denominator term in a reciprocal computation circuit (308) and a multiplier (309) and calculates update coefficient Δw_n[i]. The tap coefficient setting section (202), in a multiplier (310), an adder (311), and a delay circuit (312), adds update coefficient Δw_n[i] multiplied by step size 2μ to tap coefficient w_n[i] and generates updated tap coefficient w_n+1[i].

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.

A state machine for attenuating the transition into and out of NLP state to reduce voice clipping and to reduce echo leak in a voice over packet signal transmission. The state machine interposes two additional transitional states between the NLP active state and the NLP inactive state to eliminate the sharp transition of NLP activity. An NLP entering state is used to gradually reduce the mixing ratio of echo and voice to attenuate the transition from passage of echo in the NLP inactive state to the suppression of echo in the NLP active state. An NLP exiting state is used to gradually increase (ramping the change) the mixing ratio of echo and voice to attenuate the transition from suppression of echo in the NLP active state to passage of echo in the NLP inactive state. The rate of increase/decrease, the transition rate is determined based upon the signal parameters, including the presence of double talk and a transition rate indicator based unon these factors is generated in software to control the transition rate.

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.