Integrated frequency-domain voice coding using an adaptive spectral

Abstract

A system for encoding voice while suppressing acoustic background noise and a method for suppressing acoustic background noise in a voice encoder are described herein. The voice encoder includes a sampler that captures frames of time-domain samples of an audio signal. A voice activity detector operatively coupled to the sampler determines presence or absence of speech in the current frame. A transformer is operatively coupled to the sampler for transforming the frame of time-domain audio samples into an estimate of the power spectrum of that frame. A noise model adapter operatively associated with the transformer updates a frequency-domain noise model based on the power spectrum estimate of the current frame if the voice activity detector indicates an absence of speech in this frame. A filter computation block operatively coupled to the noise model adapter and the transform computes a spectral enhancement (noise suppression) filter based on the current power spectrum estimate and the adapted noise model. A spectral enhancement block operatively coupled to the transformer and the filter computation block applies the spectral enhancement filter to the current power spectrum estimate. A quantizer and encoder block transforms the voice encoder model parameters, including the enhanced spectral magnitudes, into a frame of encoded bits.