Gender identification in younger and older adults: use of spectral and temporal cues in noise-vocoded speech.

OBJECTIVE: The aim of this study was to investigate potential effects of age on the ability of normal-hearing (NH) adult listeners to utilize spectral and temporal cues when performing a voice gender identification task.
DESIGN: Ten younger and 10 older NH adult listeners were measured on their ability to correctly identify the speaker gender of six different vowel tokens (H-/vowel/-D) when spoken by eight speakers (four male and four female). Spectral (number of channels) and temporal cues (low-pass cut-off frequency for temporal envelope extraction) were systematically manipulated using noiseband vocoding techniques; stimuli contained 1, 4, 8, 16, or 32 spectral channels, while the low-pass cut-off frequency of the temporal envelope filter was 20, 50, 100, 200, or 400 Hz. Furthermore, the fundamental frequencies (F0s) of the vowel tokens were manipulated to create two conditions: "Expanded" (large range of F0 values) and "Compressed" (small range of F0 values).
RESULTS: In general, younger listeners performed better than the older listeners but only when stimuli were spectrally degraded. For both the Expanded and Compressed conditions, the overall performance of the younger listeners was better than that of the older listeners, suggesting age-related deficits in both spectral and temporal processing. Furthermore, a significant interaction between age group and temporal envelope cues revealed that older listeners received less benefit from increasing temporal envelope information compared with the benefit observed among younger listeners. In particular, the performance of the younger NH group (collapsed across number of channels), but not the older NH group, improved as the temporal envelope cut-off frequency was increased from 50 to 400 Hz.
CONCLUSIONS: The results reported here support previous findings of senescent declines in perceiving spectrally reduced speech and temporal amplitude modulation processing. These results suggest that when F0 values are similar to one another, younger listeners can use temporal cues alone to glean voice-pitch information but older listeners exhibit a lessened ability to use such cues. Previous studies have demonstrated the importance of temporal envelope cues in periodicity perception (e.g., gender recognition) by cochlear implant listeners. The results of this study suggest that aging affects the use of such cues, and consequently gender recognition might be poorer among older cochlear implant recipients.