Low bit rate speech coders in mobile communications systems suffer from the effects of bursty errors on the transmission channels. By using forward error control (FEC) techniques, some of these errors can be corrected. However, the channel distortions occasionally become so severe that these FEC techniques fail and so the transmitted parameters to the speech synthesizer are effectively lost. The only way to restore the lost speech then is the application of a lost frame reconstruction or replacement strategy. In this paper, we report on a novel frame reconstruction strategy for a 6. 8 Kb/s CELP-like coder. By breaking the transmitted parameters into two separate classes, we adopted different strategies for recovering from the loss of each class and so cut down on the more severe full frame reconstruction. In informal listening tests, speech intelligibility was maintained at up to 20% random frame loss of either parameter category and two consecutive full frame losses (~ 40ms of speech).
Bibliographic reference. Atungsiri, S. A. / Soheili, R. / Kondoz, A. M. / Evans, B. G. (1991): "Effective lost speech frame reconstruction for CELP coders", In EUROSPEECH-1991, 599-602.