Masking-Level Differences in the Elderly A Comparison of Antiphasic and Time-Delay Dichotic Conditions Research Article
Research Article  |   December 01, 1991
Masking-Level Differences in the Elderly
 
Author Affiliations & Notes
  • Margaret Kathleen Pichora-Fuller
    University of Toronto
  • Bruce A. Schneider
    University of Toronto
  • Requests for reprints should be sent to Bruce Schneider, Department of Psychology, Erindale Campus, University of Toronto, Mississauga, Ontario L5L 1C6.
Article Information
Hearing / Research Articles
Research Article   |   December 01, 1991
Masking-Level Differences in the Elderly
Journal of Speech, Language, and Hearing Research, December 1991, Vol. 34, 1410-1422. doi:10.1044/jshr.3406.1410
History: Received July 31, 1990 , Accepted January 3, 1991
 
Journal of Speech, Language, and Hearing Research, December 1991, Vol. 34, 1410-1422. doi:10.1044/jshr.3406.1410
History: Received July 31, 1990; Accepted January 3, 1991

Four dichotic thresholds (SπN0, S0Nπ, S0;Nτ, and SπNπτ,) were measured for young and old subjects using both burst and continuous broadband maskers. Masking-level differences (MLDs) were determined by subtracting dichotic thresholds from homophasic thresholds (S0N0 or SπNπ). The S0Nπ thresholds for the old subjects did not differ significantly from those for the young subjects in either the continuous or the burst masking noise conditions. The SπNπ thresholds for the old subjects did not differ significantly from those for the young subjects in the continuous masking noise condition, but there was a significant age effect (3 dB) when burst masking noise was used. Both young and old subjects obtained larger MLDs in continuous masking noise than in burst masking noise. MLDs for old subjects were smaller than MLDs for young subjects by 4.3, 5.0, 2.7, and 1.6 dB in burst masking noise and by 4.9, 3.5, 2.5, and 1.4 dB in continuous masking noise, respectively in the SπN0, SπNπτ, S0Nτ, and S0Nπ conditions. For young subjects there was a hierarchy n the size of the MLD obtained in the four dichotic conditions, with the MLD being significantly larger in the SπN0 and S0Nπτ, conditions; however, the size of the MLD was the same in all four conditions for the old subjects. Compared to young subjects, the performance of the old subjects was characterized by decreased ability to use homophasic cues In burst masking noise and decreased ability to use interaural difference cues. These findings were observed at four signal frequencies.

Acknowledgments
This research was supported by a grant from the Natural Sciences and Engineering Research Council of Canada. M. K. Pichora-Fuller is supported by an Ontario Ministry of Health, Health Research Personnel Development Program Fellowship (#01862). We would like to thank Jane Carey for assistance in data collection. We would also like to thank one of the reviewers, Dennis McFadden, for his thoughtful and helpful comments on an earlier version of this manuscript.
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