Age-related differences in speech variability among women.

The purpose of this study was to examine the differences in variability of several measures of the speech produced by two groups of women, one aged 20-35 years and one aged 75 years and over. The subjects read the first paragraph of the "Rainbow Passage," sustained vowels at three loudness levels, and repeated a carrier phrase in which a series of 18 syllables were embedded. Data were gathered on intraoral pressure (PIO), vocal intensity, speaking fundamental frequency (SFF), voice onset time (VOT), and phoneme duration. The F-max test and ANOVA statistics revealed that the older women exhibited greater within-subject variability than the younger women for PIO, SFF, VOT, and consonant duration. These factors required more precise temporal, respiratory, phonatory, or articulatory adjustments than did the vocal intensity tasks or vowel duration. The variability differences found in this study may reflect individual patterns of acoustic and physiologic change in the speech produced by older women.