Abstract:
Magnetic resonance imaging (MRI) is increasingly used in speech production research, particularly to obtain three-dimensional images of sustainable sounds such as fricatives or vowels. However, acoustic studies of fricatives [Shadle et al., Proc. ETRW, 193--196 (1996)] have shown that the spectral shape varies with vowel context, with the amount of variation depending on the fricative. This study, therefore, uses MRI to study the articulatory correlates of vowel context effects on fricatives. Two subjects (male French, female American English) for whom a large acoustic, aerodynamic, and articulatory database of fricatives already existed, were studied. Three different imaging methods were used that varied in acquisition time, image quality, and image extent: midsagittal turbo-flash (2 s), midsagittal spin-echo (15 s), and full coronal and axial spin-echo scans (approx. 2 min each). The subjects uttered the fricatives [f, (theta), s, (integral)] in vowel contexts [a, i, u]. Results indicate that not only are vowel context effects preserved in the longer duration images, they are often heightened. [f] showed the greatest variation in configuration with vowel context. Comparison to acoustic results and other MRI studies will be presented. [Work supported by ATR HIP Laboratories, while the first author was an invited researcher at ATR.]