Transmission system with improved speech encoder

摘要

A speech transmission system with an input speech signal applied to a speech encoder for encoding the speech signal which is transmitted via a communication channel to a speech decoder. Background noise dependent processing elements in the speech encoder and/ or speech decoder are introduced to improve the performance of the transmission system. The parameters of the perceptual weighting filter in the speech encoder are derived by calculating linear prediction coefficients from a speech signal which is processed by means of a high pass filter. An adaptive post filter in a speech decoder is bypassed when the noise level exceeds a threshold value.