Confidence Limits for Maximum Word-Recognition Scores Clinical judgments are often made regarding whether maximum word-recognition scores (PBmax) are appropriate in relation to degree of sensorineural hearing loss. In order to determine if word recognition is significantly poorer than expected, it is necessary to consider the lower boundary of PBmax associated with a particular degree of hearing ... Research Article
EDITOR'S AWARD
Research Article  |   April 01, 1995
Confidence Limits for Maximum Word-Recognition Scores
 
Author Affiliations & Notes
  • Judy R. Dubno
    Department of Otolaryngology and Communicative Sciences Medical University of South Carolina Charleston
  • Fu-Shing Lee
    Department of Otolaryngology and Communicative Sciences Medical University of South Carolina Charleston
  • Alan J. Klein
    Department of Otolaryngology and Communicative Sciences Medical University of South Carolina Charleston
  • Lois J. Matthews
    Department of Otolaryngology and Communicative Sciences Medical University of South Carolina Charleston
  • Chan F. Lam
    Department of Biometry and Epidemiology Department of Radiology Medical University of South Carolina Charleston
  • Contact author: Judy R. Dubno, Department of Otolaryngology and Communicative Sciences, Medical University of South Carolina, Charleston, SC 29425. E-mail: dubnojr@musc.edu
Article Information
Hearing Disorders / Research Issues, Methods & Evidence-Based Practice / Hearing / Research Articles
Research Article   |   April 01, 1995
Confidence Limits for Maximum Word-Recognition Scores
Journal of Speech, Language, and Hearing Research, April 1995, Vol. 38, 490-502. doi:10.1044/jshr.3802.490
History: Received June 3, 1994 , Accepted November 9, 1994
 
Journal of Speech, Language, and Hearing Research, April 1995, Vol. 38, 490-502. doi:10.1044/jshr.3802.490
History: Received June 3, 1994; Accepted November 9, 1994

Clinical judgments are often made regarding whether maximum word-recognition scores (PBmax) are appropriate in relation to degree of sensorineural hearing loss. In order to determine if word recognition is significantly poorer than expected, it is necessary to consider the lower boundary of PBmax associated with a particular degree of hearing loss for speech materials commonly used to measure word recognition. The purpose of this experiment was to define a confidence limit for PBmax from Northwestern University Test #6 (NU-6) word-recognition scores obtained from a large group of young and aged subjects with confirmed cochlear hearing loss. Word-recognition scores at several speech levels were obtained from 407 ears with a wide range of pure-tone averages. Because the characteristics of the distribution of maximum scores are not known, a procedure was developed using computer simulations to approximate the distribution of word-recognition scores corresponding to PBmax and determine the 95% confidence limit (CL). Results of the simulation were confirmed by comparing means and standard deviations of PBmax derived from experimental and simulation data. Percentages of young and aged subjects with scores outside the 95% CL are equal to their proportions in the entire subject sample. If PBmax determined from a score-level psychometric function is poorer than the 95% CL, PBmax may be considered “disproportionately” poor in relation to the degree of hearing loss. One score measured at a single arbitrary suprathreshold level that is poorer than the 95% CL suggests that the score may underestimate PBmax and that word recognition should be measured at additional levels to obtain a more reasonable estimate of the listener’s maximum word-recognition score.

Acknowledgments
This work was supported by grants P01 DC 00422 and R01 DC 00184 from the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health. The authors gratefully acknowledge the assistance of Dawn Konrad, Elizabeth Poth, Bart R. Clement, and Jayne B. Ahlstrom in data collection, and John H. Mills, Richard H. Wilson, and two anonymous reviewers for comments on a draft of this article.
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