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Browse Prior Art Database


IP.com Disclosure Number: IPCOM000008135D
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2002-May-21

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Related People

Martin T. Karanja Sedny S.J. Attia Anthony Q. Tran


With the rapid deployment of digital technology in wireless communications, the field of speech coding has seen a tremendous amount of develop- ment. Low bit-rate coding schemes such as CELP and VSFLP have gained a lot of popularity in digi- tal wireless telephony. The basis of these parametric vocoders ("voice coders") is at the encoder speech is modeled as a time-varying vocal tract filter excit- ed by a stochastic excitation sequence. At the decoder, this vocal tract filter/excitation model is reconstructed and the decoded speech samples are recovered. In this vocal tract filter/excitation coding process the output of the encoder depends not only on the present input but also on past inputs. Similarly the decoder output depends on present and past inputs. Furthermore, it is essential that the decoder states track the encoder states.