Patent ID: 8369511

Claim:
A method for suppressing background noises and residual echoes in a transmission signal, the method comprising: receiving, by an echo suppressor, the transmission signal; suppressing, by the echo suppressor, residual echoes of the transmission signal; and outputting, by the echo suppressor, an echo-suppressed transmission signal; wherein suppressing the residual echoes of the transmission signal comprises: determining a noise level to signal level ratio (NSR) and a residual echo level to signal level ratio (RSR) of the transmission signal; performing a linear predictive coding (LPC) analysis on the transmission signal to obtain a LPC predictor A(z) consisting of LPC coefficients; converting the LPC coefficients to a set of Line Spectral Frequencies (LSF Tx ); modifying the LSF Tx to obtain a first modification of the LSF Tx (LSF 1 ) and a second modification of the LSF Tx (LSF 2 ); converting the LSF 1 and LSF 2 to obtain a first linear predictor A 1 (z) and a second linear predictor A 2 (Z), respectively; processing the transmission signal using a gain-controlled filtering processing function to obtain the echo-suppressed transmission signal: F ⁡ ( z ) = G n ⁡ ( NSR ) · G r ⁡ ( RSR ) · A 1 ⁡ ( z ) A 2 ⁡ ( z ) wherein G n (NSR) is a gain controlled by the NSR; and G r (RSR) is a gain controlled by the RSR.