Characterization of tongue shape during normal speech
Kathleen A. Morrish, Maureen Stone, Thomas H. Shawker, Barbara C. Sonies · The Journal of the Acoustical Society of America · 1984
Averaged tongue shapes and polynomial equations were computed for five phonemes in order to determine aspects of tongue curve which distinguish between phonemes. Five repetitions of each of the phonemes /i/, /u/, /o/, /æ/, and /ɑ/ were produced by a normal volunteer using the carrier phrase “I can say /dVd/ again.” An ultrasound sector scanner was used to obtain midsagittal pictures of the posterior section of the tongue from vertical to 85° back into the throat. The pictures were digitized, and the resulting points were used to generate average tongue shapes and average quadratic and cubic fits for each phoneme. While both techniques provide information which allows the researcher to distinguish between the five phonemes used, only the averaged tongue shapes adequately reflect certain details of tongue shape.