Efficient algorithms for obtaining multipulse excitation for LPC coders

Since the presentation of multi-pulse excitation concept for LPC coders, by Atal and Remde, many different analysis techniques have been proposed to derive the excitation waveform. This paper describes several approaches for pulse amplitude and position determination. The original solution is compared to procedures which work directly on the residual signal, or which compute again a jointly optimal set of amplitudes, or which improve the filter parameters by taking into account the computed multi-pulse excitation. In addition, other novel techniques, based on the insertion of a long term pitch predictor in the multi-pulse analysis are presented. Also, the idea of a two stage modelization is introduced. Results of experimental evaluations for typical configurations, with respect to implementation complexity as well as speech quality, are given.