Enabling and disabling the updating of an adaptive filter for echo cancellation of a communication device is discussed. In some embodiments, an echo canceler in a communication device may include an adaptive filter enabled to update responsive to a determination that a first condition is satisfied that there is no double talk detected on the communication device, and a determination that a second condition is satisfied based, at least in part, on a performance characteristic. The adaptive filter may be disabled from updating responsive to at least one of the first condition and the second condition not being satisfied. Described is disabling the adaptive filter from updating responsive to detecting a performance characteristic of the adaptive filter to fail to meet a condition indicating that the adaptive filter is diverging. The condition may be independent of whether double-talk is determined to be present on the communication device.

Echo cancellation to alleviate timing varying channels may be provided. First, a feedback signal corresponding to one of a plurality of downstream paths and a combination upstream signal comprising a combination of upstream signals from a plurality of upstream paths may be received. Next, a plurality of echo corrected signals may be created using the feedback signal, the combination upstream signal, and a plurality of echo cancelation coefficients that each respectively correspond to each one of the plurality of echo corrected signals and that are different from each other. Then a one of the plurality of echo cancelation coefficients that corresponds to a one of the plurality of echo corrected signals that provides a best echo cancelation performance as compared to other ones of the plurality of echo corrected signals may be selected to use.

Disclosed is an echo canceller (10) including: a false echo calculator (32) that acquires current and previous filter-coefficient groups used by an adaptive filtering unit (20), and that calculates plural false echo signals by performing a filtering operation using each of the current and previous filter-coefficient groups on a sequence of reception signals (x(n)); a voice-transmission signal buffer that outputs a previous voice-transmission signal (y(n1)); an evaluation value calculator (34) that calculates plural evaluated values of an echo cancellation quantity by using the previous voice-transmission signal; a filter selector (36) that selects a new filter-coefficient group on the basis of the plural evaluated values of the echo cancellation quantity; a foreground filter (39) that performs a filtering operation using the new filter-coefficient group on the sequence of reception signals (x(n)) to generate an estimated echo component; and a subtractor (25) that subtracts the estimated echo component from a voice-transmission signal to generate a residual signal (e(n)).

A controller for an acoustic echo canceller includes a noise estimator configured to estimate a level of noise that is comprised in a microphone signal relative to an echo component, estimated by the acoustic echo canceller, comprised in the microphone signal. The controller further includes a control module configured to control the acoustic echo canceller in dependence on that estimate.

A double-talk detecting method including estimating a noise contained in a mixed signal containing at least an echo, a near-end signal and a noise to determine an estimated noise; and detecting a presence of a near-end signal contained in said mixed signal using said estimated noise.

A carrier frequency offset (CFO) estimation device includes an echo cancelling unit, performing echo cancellation on an input signal to generate an echo-cancelled signal; and a CFO estimating unit, performing CFO estimation on the echo-cancelled signal to generate an estimated CFO.

A controller for an acoustic echo canceller is described. The controller includes a noise estimator configured to estimate a level of noise that is comprised in a microphone signal relative to an echo component, estimated by the acoustic echo canceller, comprised in the microphone signal. The controller further includes a control module configured to control the acoustic echo canceller in dependence on that estimate.

A system configured to improve speech quality by performing residual echo suppression (RES). The system may detect when double talk is present in a voice conversation and may use different attenuation parameters based on a frequency of audio data. The system may perform RES on the audio data using a low attenuation value for low frequencies and a high attenuation value for high frequencies and determine that double talk is present when a difference in energy level between the low frequencies and the high frequencies is below a threshold. If double talk is present, the RES may generate output audio data using a low attenuation value for low frequencies and a high attenuation value for high frequencies. If double talk is not present, the RES may generate output audio data using a high attenuation value for low frequencies and a high attenuation value for high frequencies.

It is possible to accurately estimate the echo suppression amount for each frequency even when a nonlinear echo component is large. An estimated echo function having variables of a logarithm of a magnitude at each frequency of a reception signal, a frequency of the reception signal, a logarithm of a total reception value that is a summation of magnitudes of the reception signal or transmission of the reception signal in any frequency range, and a logarithm of an envelope of the total reception value is stored. An echo suppressing process is performed by inputting a value of a second reception signal (a result of converting the reception signal into a frequency domain) to a function representing an estimated echo to generate an echo suppressing mask, and multiplying an echo suppressing gain calculated based on this echo suppressing mask by a second transmission signal (transmission signal converted into a frequency domain).

A non-linear echo is allowed to be suppressed and voice deterioration is allowed to be suppressed. An echo suppression device for suppressing an echo generated by inputting a voice signal output from a speaker to a microphone includes a compressor on a receiving signal path for transmitting a signal of a receiving signal to the speaker. When a double-talk state has been detected, the compressor performs a compression process on a signal greater than a first threshold among the receiving signals.