Speech encoding and decoding system which modifies encoding and decoding

Abstract

The present invention relates to a speech encoder/decoder system employing digital transmission in which the encoding and decoding operations are complimentary, and these operations make use of sets of parameters which may be optimized for a speaker and for a particular digital radio link. A number of sets of parameters are determined experimentally, for example, by employing human sample groups in which perceived audio and transmission quality are tested. The encoder/decoder system then employs a group, or number, of sets of parameters serving all speakers rather than employing one fixed set of parameters. The particular set of parameters for a speaker in the encoder of a first transceiver is determined by a processor which receives values based on an analysis of the input audio signal, and then a parameter set identifier is sent within the digital signal for use by a decoder of a second transceiver. In addition, the processor of the first transceiver which receives a signal from the second transceiver may include circuitry which monitors the signal to noise ratio and bit error rate of the channel to provide a second criteria in addition to the received values based on the analysis of the input audio signal for choosing a particular set of parameters for the encoder.