A Kinematic Analysis of Coarticulation Effects on Schwa

This study investigated coarticulatory effects on schwa. The purpose was to establish a viable phonetic environment and analysis for future studies of coarticulation, particularly in motor speech disorders.

Seven female adults read 2 phrases containing 4 target words in a CVC structure embedded in the carrier phrases, "Put a CVC here" and "Get CVC a puppy." A 3D electromagnetic articulography system was used to track lingual movements during schwa production. Two indices of coarticulation were employed: (a) tongue position difference between the temporal midpoint (grand mean of each speaker) and the onset/offset of schwa immediately following or preceding a transconsonantal vowel and (b) tongue position differences between the grand mean of each speaker and each utterance repetition, both measured at the temporal midpoint of the schwa.

Both measures indicated that schwa is significantly influenced by transconsonantal corner vowels. The magnitude of coarticulation effects on schwa varied among the 4 corner vowels in the order of /i/>/ɑ/ = /æ/>/u/.

Findings support the use of schwa in future studies when examining coarticulatory effects in people with and without motor speech disorders. Some methodological issues such as selection of measurement points and speech stimuli are also discussed.