PARCAS, A new terminal analog model for speech synthesis

A new method to construct formant-type models for text-to-speech synthesis is described. The method consists of two phases: Firstly, the idealized acoustic transfer function of the uniform vocal tract is factorized into two partial transfer functions each including only every other formant of the original one. Secondly, the partial transfer functions, are approximated with proper rational, meromorphic functions. The method leads to a PARallel-CAScade model called PARCAS. In a typical text-to-speech application the model needs only 6 resonators and 16 control parameters. The special features of the PARCAS model lie in its structural compactness and simplicity to control. With this spesific structure the formant amplitudes in vowel sounds can be put close to the right levels by controlling the formant frequencies only. The same compact filter system can be used in the synthesis of all sounds including fricatives, nasals, transients and bursts. Also the mixed type excitation for voiced fricatives can easily be obtained. By informal listening of the synthesized speech it is found to be of high quality.