An articulatory study of lexicalized and epenthetic schwa using real time magnetic resonance imaging.

Debate exists about the nature of schwa in terms of articulatory planning and execution. It is commonly believed that schwa lacks a specific constriction target. Another view is that the constriction target for schwa is the mean of the language’s targeted vowels. Some have argued that both lines of thinking are correct [I. Smorodinsky, J. Acoust. Soc. Am. 109, 2446 (2001)]. Specifically, epenthetic schwas (e.g., needed) may indeed be targetless, while lexical schwas (e.g., panda) have a target. To investigate this, we collected midsagittal realtime l MR images [S. Narayanan et al., J. Acoust. Soc. Am. 115, 1771 (2004)] from two native English speakers. The speakers read sentences aloud which contained, variously, lexical or epenthetic schwas in multiple contexts. Images of the various schwas were extracted from the MR data and a profile of the vocal tract was fit to the image. If both targeted and targetless schwas exist, then they should be evident by examining the vocal tract shape in these images. Lexical schwas, if they are targeted, should have relatively low variability as compared to epenthetic schwas. Conversely, the vocal tract shape during epenthetic schwas should be highly correlated with the surrounding vowel context. [Work supported by NIH.]