Modeling vocal disorders via formant synthesis

The authors consider the synthesis of speech with various vocal characteristics, such as modal, creaky, breathy, rough, and hoarse. The relationships between the acoustical parameters of the glottal source pulses and these vocal characteristics were reviewed. Based on the acoustical parameters needed to model these vocal characteristics, a novel unified glottal source model was developed. This source model was tested with a formant synthesizer for its ability to synthesize speech with various vocal characteristics. Informal listening tests were conducted to evaluate the performance of this source model. The preliminary results are encouraging, and more rigorous testing of this model and further development of the glottal source model for each vocal characteristic are underway. Applications of this work include high-quality speech synthesis and the modeling of vocal disorders