A simplified model for simulation and transformation of speech

This paper explores a model that reduces speech production to the specification of four time varying parameters; F1 and F2, voice fundamental frequency (Fo), and a relative amplitude of the voice. The trajectory of the first two formants, F1 and F2, is treated in a series of coordinate pairs that are mapped from the F1F2 plane into a two-dimensional plane of "coefficients". These coefficients are multipliers of two empirically-based orthogonal basis vectors which, when added to a neutral vowel area function, will produce a new area function with the desired locations of F1 and F2. Thus, area functions and voice parameters extracted at appropriate time intervals can be fed into a speech simulation model to recreate the original speech. A transformation of the speech can also be imposed by manipulating the area function and voice characteristics prior to the recreation of speech by simulation. The model has initially been developed for vowel-like speech utterances but the effect of consonants on the F1F2 trajectory is also briefly addressed.