Farsi language prosodic structure, research and implementation using a speech synthesizer

In this research, we have investigated about prosodic features of Farsi (Persian) language and quantified major stress rules and some intonation rules for speech synthesis purpose. The research is mostly concentrated on pitch variations and then on durational changes. We have implemented the proposed simplified prosodic rules using a Klatt formant synthesizer, specially modified for Farsi phonemes. In order to achieve to a better speech quality, we have exploited different allophonic forms for some consonants, leading to a total of 207 Farsi diphones synthesized by the speech synthesizer. Subjective listening tests show that the addition of the prosodic features drastically increases both the intelligibility and naturalness of the synthesized speech. The synthesizer is software-implemented on a Pentium PC and operates in real-time.