Isovowel lines for the evaluation of vowel formant structure in speech disorders.

This report describes a system of isovowel lines in the F1-F2 and F2-F3 planes and demonstrates how these linear approximations to vowel formant frequencies for a diverse sample of speakers can be used to evaluate the vowel formant structures of individuals with speech disorders. The application to disordered speech is illustrated with data for dysarthric adults, deaf adolescents, and young children with developmental errors of: Formula: (See Text) production.