No abstract

Research in speech synthesis is presently concerned with methods for improving intelligibility and naturalness. But most work to date has dealt with intelligibility, i.e., the synthesized speech is intelligible but monotone and machinelike in quality. Although this type of speech is useful in some applications, the users of speech synthesizers are demanding a more natural sounding synthesized speech. We are addressing this issue in our research. In particular we are studying the influence of the glottal source function on the production of synthesized speech. Our data base consists of inverse filtered speech, ultra-high-speed laryngeal films, and the electroglottograph waveforms, all temporally synchronized in our experiments. We use the experimentally derived source waveforms obtained from these various method as the excitation for a serial/parallel Klatt formant synthesizer to synthesize sentences. We then evaluate the naturalness of this synthetic speech by listening tests. Our goal is to rank order the contribution of different source parameters to the naturalness of synthetic speech. More specifically, we report on our results to date of the effect of source-tract interaction upon the production of natural sounding speech.