Patent ID: 8391471

Claim:
An echo suppressing apparatus operable with a sound output device for outputting sound based on a reference sound signal and a sound processing device for processing an observed sound signal based on a received sound, the echo suppressing apparatus comprising: an echo removal section for presuming an echo component of the observed sound signal on the basis of both the observed sound signal and the reference sound signal, and removing the echo component from the observed sound signal; a ratio calculation section for calculating a power ratio of the observed sound signal to the reference sound signal; a correction amount calculation section for calculating, based on with the calculated power ratio, a correction amount for the observed sound signal from which the echo component is removed; a correction section for correcting, based on the calculated correction amount, the observed sound signal from which the echo component is removed, so as to suppress a residual echo remaining in the observed sound signal from which the echo component is removed; and an output section for outputting the corrected observed sound signal to the sound processing device, wherein the correction amount calculation section comprises: a derivation section for deriving a spectrum based on the observed sound signal from which the echo component is removed; an envelope derivation section for deriving a spectrum envelope based on the derived spectrum; and a coefficient section for obtaining a correction coefficient for correcting the spectrum envelope in accordance with the power ratio when the power ratio is equal to or lower than a given value, and the correction amount calculation section calculates a correction amount for correcting a spectrum shape of the observed sound signal from which the echo component is removed in the basis of the result obtained by correcting the spectrum envelope with the correction coefficient.