Abstract: A synthesis method in which that part of each interval of the original signal which contains the fundamental information is left unchanged, and only the remaining part of the interval is altered. In this way, not only is processing time reduced, but the natural sound of the synthetic signal is also improved. The main part of the interval is an exact reproduction of the original signal. At least the waveforms associated to voiced sounds are subdivided into a plurality of intervals, corresponding to the responses of the vocal duct to a series of excitation impulses of the vocal cords, synchronous with the fundamental frequency of the signal. Each interval is subjected to a weighting. The signals resulting from the weighting are replaced with a replica thereof shifted in time by an amount that depends on a prosodic information. The synthesis is then carried out by overlapping and adding the shifted signals.