The present document specifies algorithms for front-end feature extraction and their transmission which form part of a system for distributed speech recognition. The specification covers the following components:

• the algorithm for front-end feature extraction to create Mel-Cepstrum parameters;
• the algorithm to compress these features to provide a lower data transmission rate;
• the formatting of these features with error protection into a bitstream for transmission;
• the decoding of the bitstream to generate the front-end features at a receiver together with the associated algorithms for channel error mitigation.

The present document does not cover the "back-end" speech recognition algorithms that make use of the received DSR front-end features.

The algorithms are defined in a mathematical form or as flow diagrams. Software implementing these algorithms written in the "C" programming language is contained in the .ZIP file which accompanies the present document. Conformance tests are not specified as part of the standard. The recognition performance of proprietary implementations of the standard can be compared with those obtained using the reference "C" code on appropriate speech databases.

It is anticipated that the DSR bitstream will be used as a payload in other higher level protocols when deployed in specific systems supporting DSR applications. In particular, for packet data transmission, it is anticipated that the IETF AVT RTP DSR payload definition (see bibliography) will be used to transport DSR features using the frame pair format described in clause 6.