A quasi-experimental longitudinal paired-samples study was carried out to explore, whether aging for 5 years can (1) audibly and (2) measurably change women's vocalisations, and if so, on which acoustic information (3) the listeners' performance possibly could relay on and (4) which parameters can contribute to detect the chronological difference.
Results indicate that (1) listeners can significantly correctly judge this difference based on sustained /i/ and /u/ vowels, but much better based on (spontaneous) speech samples. (2) Parameters depicting pitch, vowel resonance, voice perturbations, tremor and spectral energy distributions differ (significantly) between chronologically and perceptually younger and older samples. (3) Listeners tend to judge vowel samples as older, if increased (amplitude) perturbations can be measured, but in speech samples there seem to be overriding and objectively more reliable features. (4) The most reliable age-indicating measures in this study in speech samples are durations / tempo measures - in vowels F0 and tremor.
Bibliographic reference. Brückl, Markus (2007): "Women's vocal aging: a longitudinal approach", In INTERSPEECH-2007, 1170-1173.