ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

4pSC19. Formant synthesis: Turning cascade into parallel with applications to the Klatt synthesizer.

Qiguang Lin

Jingyun Zou

CAIP Ctr., Rutgers Univ., Piscataway, NJ 08855-1390

Formant speech synthesis is one of the successful approaches for text-to-speech synthesis. Usually, formants are connected in parallel for the synthesis of consonants and in either cascade or parallel for vowels. The cascade structure requires a fewer number of control parameters and the synthesized spectrum is guaranteed to be correct. It is best suited for vowel synthesis. However, because of the necessary interchange of a parallel and cascade structure, it is not trivial to maintain good continuity in resonance modes. On the other hand, vowels can also be synthesized by the same parallel formant synthesizer used for consonants. This solution avoids the interchange of resonators, but more control parameters are necessitated and the resultant spectrum may be distorted. In this paper, a method is described which mathematically turns a cascade configuration into parallel. No additional parameters, that is, the complex amplitudes of formants, are explicitly required. Instead, these parameters are determined from given formant frequencies, bandwidths, and the higher-pole correction. The method thus maintains continuity in resonance modes without requiring extra parameters. The method has been integrated into the Klatt synthesizer. Synthetic speech generated using the proposed method will be demonstrated. [Work partially supported by ARPA Contract No. DAST 63-93-C-0064.]