Fundamental Frequency During Phonetically Governed Devoicing in Normal Young and Aged Speakers

Age-related changes in the laryngeal system can be perceived as altered vocal pitch and increased pitch variability. However, reports vary as to the nature and extent of an age effect on fundamental frequency (F0) for analyses taken over long segments of connected speech. Analysis of F0 across a smaller time frame may be more informative. Young speakers show an increase in F0 associated with phonetically governed devoicing gestures that is likely mediated by increased vocal fold stiffness. Anatomic and neurophysiologic changes in the aged larynx may limit the role of increased vocal fold stiffness in the devoicing gesture. This study tests the hypothesis that aged speakers show a smaller increase in F0 in association with the devoicing gesture for production of an intervocalic voiceless obstruent than do young speakers. Normal young and aged speakers produced a short sentence containing an intervocalic voiceless obstruent. Measures of F0 were obtained for ten cycles before voice offset and ten cycles after voice onset. Young speakers showed a small increase in F0 during devoicing whereas aged speakers showed a decrease in F0 during devoicing. Aged speakers seem to rely more on vocal fold abduction rather than a combination of abduction and tensing to achieve devoicing.