Stimulus Ratio Effects on Speech Discrimination by Children and Adults This investigation examined the response strategies and discrimination accuracy of adults and children aged 5–10 as the ratio of same to different trials was varied across three conditions of a “change/no-change” discrimination task. The conditions varied as follows: (a) a ratio of one-third same to two-thirds different trials (33% same), ... Research Article
Research Article  |   June 01, 1991
Stimulus Ratio Effects on Speech Discrimination by Children and Adults
 
Author Affiliations & Notes
  • Joan E. Sussman
    State University of New York at Buffalo
  • Requests for reprints should be sent to Joan E. Sussman, PhD, State University of New York at Buffalo, Department of Communicative Disorders and Science, Faculty of Social Sciences, 109 Park Hall, Buffalo, NY 14260.
Article Information
Hearing / Research Articles
Research Article   |   June 01, 1991
Stimulus Ratio Effects on Speech Discrimination by Children and Adults
Journal of Speech, Language, and Hearing Research, June 1991, Vol. 34, 671-678. doi:10.1044/jshr.3403.671
History: Received November 20, 1989 , Accepted August 24, 1990
 
Journal of Speech, Language, and Hearing Research, June 1991, Vol. 34, 671-678. doi:10.1044/jshr.3403.671
History: Received November 20, 1989; Accepted August 24, 1990

This investigation examined the response strategies and discrimination accuracy of adults and children aged 5–10 as the ratio of same to different trials was varied across three conditions of a “change/no-change” discrimination task. The conditions varied as follows: (a) a ratio of one-third same to two-thirds different trials (33% same), (b) an equal ratio of same to different trials (50% same), and (c) a ratio of two-thirds same to one-third different trials (67% same). Stimuli were synthetic consonant-vowel syllables that changed along a place of articulation dimension by formant frequency transition. Results showed that all subjects changed their response strategies depending on the ratio of same-to-different trials. The most lax response pattern was observed for the 50% same condition, and the most conservative pattern was observed for the 67% same condition. Adult response patterns were most conservative across condition. Differences in discrimination accuracy as measured by P(C) were found, with the largest difference in the 5- to 6-year-old group and the smallest change in the adult group. These findings suggest that children’s response strategies, like those of adults, can be manipulated by changing the ratio of same-to-different trials. Furthermore, interpretation of sensitivity measures must be referenced to task variables such as the ratio of same-to-different trials.

Acknowledgments
This research was supported in part by a research award from the American Speech-Language-Hearing Foundation and Psi lota Xi. The current research was reported in part at the 111 th Meeting of the Acoustical Society of America in May 1986 and at the Annual Convention of the American Speech-Language-Hearing Association in November 1986. The investigation was conducted at the State University of New York at Geneseo with materials generated at Purdue University. I gratefully acknowledge both departments for the use of their facilities, particularly the department of Speech Pathology and Audiology at SUNY-Geneseo. Special thanks are extended to S. Appelle for discussions and comments on the manuscript and to the two anonymous reviewers for their thoughtful suggestions.
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