Patent ID: 8385558
Filing Date: 2013-02-26
Classification: H04M

Abstract:
1. A method to be executed on a computing device for determining echo presence, the method comprising: receiving an input audio signal at a microphone associated with the computing device; converting the input audio signal to a microphone signal and providing the microphone signal to a processor of the computing device; determining a presence of echo in the input audio signal at the processor by predicting an echo signal component of the input audio signal employing short length adaptive filters and a speaker signal, wherein the speaker signal is received from a circuit providing the speaker signal to a speaker; aligning sub-band components of the input audio signal at the processor, mic[n,k], and the speaker signal, spk[n,k], based on timestamps associated with each component with n representing a timeframe index and k representing a sub-band frequency; predicting the echo signal component of the input audio signal at the processor, mic[n, k], based on past samples of the speaker signals {spk[n-d, k], spk[n-d-1, k], spk[n-d-2, k]}, where d=0, 1, 2, . . . L0, and L0 being a causal-delay search range; predicting the echo signal component of the input audio signal at the processor, mic[n-d, k], based on the speaker signals {spk[n, k], spk[n-1, k], spk[n-2, k]}, where d=1, 2, . . . L1, and L1 is acausal-delay search range; computing a prediction parameter Echo Return Loss Enhancement “ERLE” based on a variance quotient of the input audio signal at the processor, mic[n, k], mic[n, k]-mic[n,k, d], and a difference between mic[n, k] and the predicted echo signal component, mic[n, k, d] for causal and acausal ranges; determining a maximum ELRE across the sub-bands at the processor; comparing the maximum ERLE to a predefined threshold for determining the presence of the echo at the processor; and if the prediction indicates the presence of echo, implementing a predefined measure at the processor.