Effects of Stimulus Variability on Speech Perception in Listeners With Hearing Impairment Traditional word-recognition tests typically use phonetically balanced (PB) word lists produced by one talker at one speaking rate. Intelligibility measures based on these tests may not adequately evaluate the perceptual processes used to perceive speech under more natural listening conditions involving many sources of stimulus variability. The purpose of this ... Research Article
Research Article  |   December 01, 1997
Effects of Stimulus Variability on Speech Perception in Listeners With Hearing Impairment
 
Author Affiliations & Notes
  • Karen Iler Kirk, PhD
    Indiana University School of Medicine Indianapolis
    Department of Otolaryngology–Head and Neck Surgery, Indiana University School of Medicine, 702 Barnhill Drive, Indianapolis, IN 46202
  • David B. Pisoni
    Indiana University School of Medicine Indianapolis
  • R. Christopher Miyamoto
    Indiana University School of Medicine Indianapolis
  • Corresponding author: e-mail: kkirk@iupui.edu
  • Currently affiliated with the University of Cincinnati
    Currently affiliated with the University of Cincinnati×
Article Information
Hearing & Speech Perception / Hearing Disorders / Speech, Voice & Prosody / Hearing / Research Articles
Research Article   |   December 01, 1997
Effects of Stimulus Variability on Speech Perception in Listeners With Hearing Impairment
Journal of Speech, Language, and Hearing Research, December 1997, Vol. 40, 1395-1405. doi:10.1044/jslhr.4006.1395
History: Received July 19, 1995 , Accepted April 30, 1997
 
Journal of Speech, Language, and Hearing Research, December 1997, Vol. 40, 1395-1405. doi:10.1044/jslhr.4006.1395
History: Received July 19, 1995; Accepted April 30, 1997

Traditional word-recognition tests typically use phonetically balanced (PB) word lists produced by one talker at one speaking rate. Intelligibility measures based on these tests may not adequately evaluate the perceptual processes used to perceive speech under more natural listening conditions involving many sources of stimulus variability. The purpose of this study was to examine the influence of stimulus variability and lexical difficulty on the speech-perception abilities of 17 adults with mild-to-moderate hearing loss. The effects of stimulus variability were studied by comparing word-identification performance in single-talker versus multipletalker conditions and at different speaking rates. Lexical difficulty was assessed by comparing recognition of "easy" words (i.e., words that occur frequently and have few phonemically similar neighbors) with "hard" words (i.e., words that occur infrequently and have many similar neighbors). Subjects also completed a 20-item questionnaire to rate their speech understanding abilities in daily listening situations. Both sources of stimulus variability produced significant effects on speech intelligibility. Identification scores were poorer in the multiple-talker condition than in the single-talker condition, and word-recognition performance decreased as speaking rate increased. Lexical effects on speech intelligibility were also observed. Word-recognition performance was significantly higher for lexically easy words than lexically hard words. Finally, word-recognition performance was correlated with scores on the self-report questionnaire rating speech understanding under natural listening conditions. The pattern of results suggest that perceptually robust speech-discrimination tests are able to assess several underlying aspects of speech perception in the laboratory and clinic that appear to generalize to conditions encountered in natural listening situations where the listener is faced with many different sources of stimulus variability. That is, wordrecognition performance measured under conditions where the talker varied from trial to trial was better correlated with self-reports of listening ability than was performance in a single-talker condition where variability was constrained.

Acknowledgments
This research was supported by NIDCD Research Grants DC-00064, DC-00111, and DC-00126 and NIDCD Training Grant DC-00012 to Indiana University. We thank Julia Renshaw, Molly Pope, and Michelle Wagner-Escobar for their help and assistance in recruiting the patients used in this study. We also thank Mitchell Sommers, Scott Lively, John Karl, and Luis Hernandez for technical assistance at various stages of the project. The assistance of Darla Sallee and Linette Caldwell in the preparation of this manuscript is also acknowledged.
Order a Subscription
Pay Per View
Entire Journal of Speech, Language, and Hearing Research content & archive
24-hour access
This Article
24-hour access