An acoustic investigation on the effect of speaking rate on vowel space and coarticulation in Toda VCV sequences

This study analyzes the effect of consonant context and speaking rate on vowel space and coarticulation in Toda vowel-consonant-vowel (VCV) sequences. Five vowels, /a/, /e/, /i/, /o/, /u/, and two intervocalic consonants, /p/ (labial) and /t/ (alveolar), are considered to form asymmetrical VCV sequences in slow and very fast speaking rates. Acoustic analysis using first and second formants (F1 and F2) shows a significant change in vowel space across speaking rates in a consonant specific manner. Quantification of range and extent of coarticulation using F2 are presented to carry out acoustic analysis of both anticipatory and carryover coarticulation. Significant effect of consonant context is found for both anticipatory and carryover coarticulation in most of the VCV sequences. Increase in speaking rate is found to significantly drop both anticipatory and carryover coarticulation range in the context of alveolar consonants. Results from these acoustic analyses indicate that there are differences in the nature in which rate and consonant context affect the coarticulatory organization.