Production and perception of Greek vowels in normal and cerebral palsy speech

Abstract

This study investigates the perceptual consequences and differences in vowel pro-duction between cerebral palsy (CP) afflicted Greek speakers and their normal counterparts. Formant (F1 and F2) values for the five vowels of Modern Greek were extracted from productions of both male and female speakers in stressed and un-stressed conditions. These same productions were presented to normal hearing Greek speakers for vowel identification. Aggregate vowel spaces constructed from the mean F1 and F2 values reveal that the male CP speakers’ productions more closely resemble normal female spaces than that of normal males, but has only a slight impact on reducing intelligibility. Unstressed vowel productions from female CP speakers reduced intelligibility most significantly, in particular for the vowel [o]. Significantly greater standard errors around formant means for the CP speakers’ unstressed vowel productions suggest these speakers have considerably more diffi-culty in controlling vocal tract shape when using less vocal effort.