Patent ID: 9076455
Filing Date: 2015-07-07
Classification: G10K,G10L

Abstract:
1. A method for echo compensation of at least one audio microphone signal that includes an echo signal contribution due to an audio loudspeaker signal in a loudspeaker-microphone system, the method comprising: converting overlapped sequences of the audio loudspeaker signal from a time domain to a frequency domain and obtaining a time series of short-time loudspeaker spectra with a predetermined number of sub-bands, wherein the sequences have a predetermined sequence length and an amount of overlapping of the overlapped sequences predetermined by a loudspeaker sub-sampling rate; temporally interpolating the time series of short-time loudspeaker spectra, including, for each pair of temporally adjacent short-time loudspeaker spectra, calculating an interpolated short-time loudspeaker spectrum by weighted addition of the temporally adjacent short-time loudspeaker spectra; computing an estimated echo spectrum with its sub-band components for at least one current loudspeaker spectrum by weighted adding of a current short-time loudspeaker spectrum and previous short-time loudspeaker spectra, up to a predetermined maximum time delay, wherein: first filter coefficients are used for weighting the current loudspeaker spectrum and the corresponding previous short-time loudspeaker spectra with increasing time delay; second filter coefficients are used for weighting the interpolated short-time loudspeaker spectra temporally adjacent to the current loudspeaker spectrum and the corresponding previous short-time loudspeaker spectra; and the first and second filter coefficients are estimated by an adaptive algorithm; converting overlapped sequences of the audio microphone signal from the time domain to the frequency domain and obtaining a time series of short-time microphone spectra with a predetermined number of sub-bands, wherein the sequences have a predetermined sequence length and an amount of overlapping of the overlapped sequences predetermined by a microphone sub-sampling rate; adaptively filtering the time series of short-time microphone spectra of the microphone signal by at least subtracting a corresponding estimated echo spectrum from a corresponding microphone spectrum, where the first and second filter coefficients are applied and sub-band components of the spectra are used for the subtraction; converting the filtered time series of short-time spectra of the microphone signal to overlapped sequences of a filtered audio microphone signal; and overlapping the sequences of the filtered audio microphone signal to generate an echo compensated audio microphone signal.