Effect of Age on Silent Gap Discrimination in Synthetic Speech Stimuli The difficulty that older listeners experience understanding conversational speech may be related to their limited ability to use information present in the silent intervals (i.e., temporal gaps) between dynamic speech sounds. When temporal gaps are present between nonspeech stimuli that are spectrally invariant (e.g., noise bands or sinusoids), older listeners ... Research Article
Research Article  |   April 01, 2004
Effect of Age on Silent Gap Discrimination in Synthetic Speech Stimuli
 
Author Affiliations & Notes
  • Jennifer Lister
    University of South Florida, Tampa
  • Kenton Tarver
    University of South Florida, Tampa
  • Corresponding author: e-mail: jlister@chuma.l.cas.usf.edu
  • Contact author: Jennifer Lister, PhD, University of South Florida, Department of Communications Sciences and Disorders, 4202 E. Fowler Avenue PCD 1017, Tampa, FL 33620. E-mail: jlister@chuma.l.cas.usf.edu
Article Information
Hearing & Speech Perception / Acoustics / Hearing Disorders / Augmentative & Alternative Communication / Speech, Voice & Prosody / Hearing / Research Articles
Research Article   |   April 01, 2004
Effect of Age on Silent Gap Discrimination in Synthetic Speech Stimuli
Journal of Speech, Language, and Hearing Research, April 2004, Vol. 47, 257-268. doi:10.1044/1092-4388(2004/021)
History: Received May 21, 2003 , Accepted October 7, 2003
 
Journal of Speech, Language, and Hearing Research, April 2004, Vol. 47, 257-268. doi:10.1044/1092-4388(2004/021)
History: Received May 21, 2003; Accepted October 7, 2003
Web of Science® Times Cited: 23

The difficulty that older listeners experience understanding conversational speech may be related to their limited ability to use information present in the silent intervals (i.e., temporal gaps) between dynamic speech sounds. When temporal gaps are present between nonspeech stimuli that are spectrally invariant (e.g., noise bands or sinusoids), older listeners are less able to resolve temporal gaps than are younger listeners. It has also been demonstrated that temporal gap perception deteriorates as the frequency difference between the sounds bordering the silent gap increases, and this effect becomes more pronounced with age (J. Lister, J. Besing, & J. Koehnke, 2002; J. Lister, J. Koehnke, & J. Besing, 2000). In this study, the effect of age on the ability to discriminate temporal gaps in dynamic stimuli (i.e., changing in frequency and duration over time) was measured in a gap duration discrimination (GDD) task. The participants were two groups of listeners with normal hearing sensitivity through at least 4000 Hz: (a) ages 21–38 years and (b) ages 50–72 years. Stimuli simulated the frequency characteristics of 1 consonant (/s/), a steady-state vowel (/a/), a weak diphthong (e/i/), and a voiced bilabial plosive (/ burst/) in 6 combinations: (a) /s-a/, (b) /s-e/i/, (c) /a-a/, (d) / ei-ei/, (e) / burst-a/, and (f) / burst-e/i/. For each of the 6 phoneme combinations, 2 conditions of stimulus duration were used: (a) fixed, meaning that the durations of leading and trailing noises were fixed at values typical for the speech sounds being simulated, and (b) random, meaning that duration varied randomly within a range acceptable for accurate perception of the speech contrasts. Gap duration difference limens (GDDLs) were significantly larger for the older listeners than for younger listeners. For both groups, GDDLs were poorer for the spectrally dynamic marker pairs (e.g., /burst-ei/) than for the marker pairs that were relatively stable in frequency over time (/a-a/). GDD performance also was poorer for the random condition than for the fixed condition. Listener age and hearing sensitivity were significantly correlated, and age was not significantly correlated with GDD when controlling for hearing sensitivity. The authors conclude that temporal resolution (as measured by gap discrimination) is affected by age, stimulus complexity, and, perhaps, by hearing sensitivity in a speech context.

Acknowledgments
This study was supported by University of South Florida Research and Creative Scholarship Grant 1219–933-RO. Portions of this work were presented at the 2001 meetings of the Association for Research in Otolaryngology and the Acoustical Society of America. We would like to thank Catherine Rogers for her assistance with phoneme synthesis and Richard Roberts for his comments on an earlier version of this article.
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