Active change in American English dialects and their role in age perception.

Abstract

Prior studies on vocal aging have varied with respect to the perceptual relevance of vowel formants. Two patterns have been (inconsistently) observed: formant lowering due to age-induced laryngeal lowering and formant centralization. A third hypothesis was investigated here: that active changes in the vowel systems of American English dialects, lead by younger (especially female) speakers, can themselves serve as vocal age cues independent of the cited (physiological) changes. One active vowel change is the California vowel shift, involving the lowering/backing of [I], [E], and [ae], one that has also been observed in young speakers in Florida and elsewhere. Would such systematic differences in vowel quality occurring frequently in younger speech play a significant role in female voice age perception? Speech samples were collected from 20 young and 20 middle-aged female residents of northern Florida under four conditions: (a) while conversing with another speaker matched versus mismatched in age category and (b) having been trained (versus untrained) to accurately simulate the California vowel shift in younger speakers. Acoustic analysis and age estimation studies were conducted to determine if the presence of a natural/simulated “younger” dialect shifted perceived age and the extent of any shift relative formant lowering and formant centralization.