Abstract:

Slowing of neural processes due to aging may cause effects in motor speech production. In a study of /w/, Slawinski [E. B. Slawinski, J. Acoust. Soc. Am. 95, 2221--2230 (1994)] found a slower prevoicing stage, and a smaller off-glide frequency range for older speakers than younger. The latter finding suggests that older speakers centralize their articulatory gestures. Articulatory gestures may also centralize at faster speech rates. The present study compared midsagittal tongue gestures for /w/, for older versus younger subjects, matched for rate of speech. Ten female subjects (five aged 21--29, five aged 64--71) repeated: /(schwa)wVp/ and /(schwa)gwVp/ using the vowels /i,a,u/, five times each, while ultrasound video recordings were made. The hypothesis was that coarticulation would cause different /w/ positions, (higher in /g/ context). If older subjects centralize tongue position for /w/, they might produce an even greater difference, if the high /g/ tongue position facilitated a more extreme /w/. Target frames were digitized and tongue surface edges were extracted [M. Unser and M. Stone, J. Acoust. Soc. Am. 91, 3001-3007 (1992)]. The distances between /w/ and /(g)w/ were determined using L2 norms. For two older and two younger speakers, rate effects were observed and age effects were not.