Psychometric Equivalence of Recorded Spondaic Words as Test Items In the determination of the speech-reception threshold (SRT), spondaic words are assumed to be homogeneous with respect to intelligibility; and the assumption of equal intelligibility requires that the words be comparable for all signal levels. Previous attempts to assess the equal intelligibility assumption using word thresholds as the sole criterion ... Research Article
Research Article  |   June 01, 1998
Psychometric Equivalence of Recorded Spondaic Words as Test Items
 
Author Affiliations & Notes
  • Robert C. Bilger
    University of Illinois at Urbana-Champaign Department of Speech and Hearing Science
  • Melanie L. Matthies
    University of Illinois at Urbana-Champaign Department of Speech and Hearing Science
  • Ted A. Meyer
    University of Illinois at Urbana-Champaign Department of Speech and Hearing Science
  • Scott K. Griffiths
    University of Illinois at Urbana-Champaign Department of Speech and Hearing Science
  • Corresponding author: e-mail: tmeyer@iupui.edu
  • Currently affiliated with Boston University, Department of Communication Disorders
    Currently affiliated with Boston University, Department of Communication Disorders×
  • Currently affiliated with Indiana University, DeVault Otologic Research Laboratory
    Currently affiliated with Indiana University, DeVault Otologic Research Laboratory×
  • Currently affiliated with the University of Florida, Department of Communication Processes and Disorders
    Currently affiliated with the University of Florida, Department of Communication Processes and Disorders×
Article Information
Speech, Voice & Prosodic Disorders / Hearing Disorders / Speech, Voice & Prosody / Hearing / Research Articles
Research Article   |   June 01, 1998
Psychometric Equivalence of Recorded Spondaic Words as Test Items
Journal of Speech, Language, and Hearing Research, June 1998, Vol. 41, 516-526. doi:10.1044/jslhr.4103.516
History: Received July 27, 1997 , Accepted November 24, 1997
 
Journal of Speech, Language, and Hearing Research, June 1998, Vol. 41, 516-526. doi:10.1044/jslhr.4103.516
History: Received July 27, 1997; Accepted November 24, 1997

In the determination of the speech-reception threshold (SRT), spondaic words are assumed to be homogeneous with respect to intelligibility; and the assumption of equal intelligibility requires that the words be comparable for all signal levels. Previous attempts to assess the equal intelligibility assumption using word thresholds as the sole criterion are not an adequate basis for specifying the equality of intelligibility. In the present study, the recorded spondaic words (Tillman recording) were analyzed in an attempt to create a more homogeneous set of spondaic words for future laboratory work. To achieve this goal, the data reported by Young, Dudley, and Gunter (1982) and data collected in our laboratory were fitted to a logistic function (psychometric function) from which a 50% point (threshold) and slope were obtained. To specify their acoustical parameters, the recorded spondaic words were digitized and the RMS level and duration of each syllable and word were calculated. None of the RMS or duration measures were correlated with word thresholds, so no attempt was made to equate level or duration. On the other hand, when the threshold of each word was adjusted to equal the mean threshold of the set (n = 36), the dispersion among word thresholds and slopes was greatly reduced. Further, we recommend that small sets of "equally intelligible" spondaic words not be used for clinical testing because set size is a strong factor in determining threshold for spondees (Meyer & Bilger, 1997; Punch & Howard, 1985).

Acknowledgments
This work was supported by a grant (DC 00174) from the National Institute on Deafness and Other Communication
Disorders of NIH. The authors would like to thank the reviewers for their helpful comments.
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