Effect of Age on F 0 Difference Limen and Concurrent Vowel Identification

Abstract

Purpose To investigate the effect of age on voice fundamental frequency (F 0 ) difference limen (DL) and identification of concurrently presented vowels. Method Fifteen younger and 15 older adults with normal audiometric thresholds in the speech range participated in 2 experiments. In Experiment 1, F 0 DLs were measured for a synthesized vowel. In Experiment 2, accuracy in identifying concurrently presented vowel pairs was measured. Vowel pairs were formed from 5 synthesized vowels with F 0 separations ranging from 0 to 4 semitones. Results Younger adults had smaller (better) F 0 DLs than older adults. For the older group, age was significantly correlated with F 0 DLs. Younger adults identified concurrent vowels more accurately than older adults. When the vowels in the pairs had different formants, both age groups benefited similarly from F 0 separation. Interestingly, when both constituent vowels had identical formants, F 0 separation was deleterious, especially for older adults. Pure-tone average threshold did not correlate significantly with either F 0 DL or accuracy in concurrent vowel identification. Conclusion Age-related declines were confirmed for F 0 DLs, identification of concurrently spoken vowels, and benefit from F 0 separation between vowels with identical formants. This pattern of findings is consistent with age-related deficits in periodicity coding.