A test of formant frequency analyzes with simulated child-like vowels.

Abstract

Speech production by children is typically characterized by a fairly high fundamental frequency of phonation and a short vocal tract length that produces high formant frequencies. Together these two characteristics contribute to the difficulty of making accurate measurements of the formants because the vocal tract transfer function may be undersampled by the voice source harmonics. In addition, the close proximity of the low-numbered harmonics (including the fundamental) to a formant may lead to strong nonlinear interaction of the acoustic pressures in the vocal tract and the glottal airflow. The purpose of this study was to use standard spectrographic and LPC techniques, as well as new pitch-synchronous method, to measure formant frequencies of child-like vowels that have been simulated with a speech production model. Each vowel will be simulated with two different representations of the voice source: a glottal area model that allows for nonlinear source-tract interaction and a glottal flow model in which vocal tract characteristics cannot affect the source. The results of the analyzes will be compared to the actual formant frequencies calculated directly from the known vocal tract area functions used to generate the vowels. [Research supported by NIH R01-DC04789.]