Abstract:
Rules are being developed for controlling a formant synthesizer (HLsyn) in which ten higher-level parameters control changes in vocal-tract natural frequencies, areas of four orifices, and other aspects of articulation. The input to the rules is a phonetic sequence labeled in terms of distinctive features. The rules operate in four stages. First, the time locations of a sequence of landmarks are established. The landmarks are of three types: locations of vowel nuclei and offglides, locations of amplitude minima for glides, and times of formation and release of consonantal constrictions. Second, formant trajectories between vowel landmarks are derived. Third, these vowel-to-vowel formant movements are modified by the effects of consonantal constrictions, working from left to right. Fourth, the effects of secondary consonant articulations are added, including introduction of a velopharyngeal opening, spreading or constricting glottal movements, and influences of segmentally related vocal fold stiffening and vocal tract expansion or contraction for obstruents. Trajectories of the parameters are, for the most part, constructed from quarter-cycle segments of sinusoids. Examples of synthesis of simple VCVCV utterances illustrate the vowel-to-vowel coarticulation and context-dependent vowel formants that result from application of the rules. [Supported in part by NIH Grant No. MH52358.]