Effect of Step Size on Clinical and Adaptive 2IFC Procedures in Quiet and in a Noise Background Audibility thresholds for a 1000-Hz sinusoid were measured with a standard clinical (CLIN) procedure and a two-interval, forced-choice (2IFC) adaptive procedure bracketing 79% correct. Both used 2- and 5-dB step sizes in quiet and in a continuous, broadband noise background. Clinical thresholds were from 2 to 4 dB higher than ... Research Article
Research Article  |   August 01, 1996
Effect of Step Size on Clinical and Adaptive 2IFC Procedures in Quiet and in a Noise Background
 
Author Affiliations & Notes
  • Lynne Marshall
    Naval Submarine Medical Research Laboratory Groton, CT
  • Thomas E. Hanna
    Naval Submarine Medical Research Laboratory Groton, CT
  • Richard H. Wilson
    Veterans Administration Medical Center Mountain Home, TN
  • Contact author: Lynne Marshall, PhD, Box 900, Subase NLON, Groton, CT 06349-5900.
    Contact author: Lynne Marshall, PhD, Box 900, Subase NLON, Groton, CT 06349-5900.×
Article Information
Hearing & Speech Perception / Acoustics / Research Issues, Methods & Evidence-Based Practice / Hearing / Research Articles
Research Article   |   August 01, 1996
Effect of Step Size on Clinical and Adaptive 2IFC Procedures in Quiet and in a Noise Background
Journal of Speech, Language, and Hearing Research, August 1996, Vol. 39, 687-696. doi:10.1044/jshr.3904.687
History: Received December 6, 1994 , Accepted January 28, 1996
 
Journal of Speech, Language, and Hearing Research, August 1996, Vol. 39, 687-696. doi:10.1044/jshr.3904.687
History: Received December 6, 1994; Accepted January 28, 1996

Audibility thresholds for a 1000-Hz sinusoid were measured with a standard clinical (CLIN) procedure and a two-interval, forced-choice (2IFC) adaptive procedure bracketing 79% correct. Both used 2- and 5-dB step sizes in quiet and in a continuous, broadband noise background. Clinical thresholds were from 2 to 4 dB higher than 2IFC thresholds, depending on the condition. Step size had a larger effect on the CLIN thresholds than the 2IFC thresholds. For the CLIN procedure, thresholds with a 2-dB step size were 1.4 dB lower than with a 5-dB step size. For the 2IFC procedure, thresholds with a 2-dB step size were 0.8 dB higher than with a 5-dB step size. Reliability, as measured by the intrasubject standard deviation, was better for the 2IFC than for the CLIN procedure and better in noise than in quiet. Reliability was unaffected by step size. Adding extra trials to the 2IFC adaptive track decreased the variability across threshold estimates, but more for the noise background than the quiet background. The efficiency of the 2IFC procedure was fairly constant across track length in noise, but decreased for longer track lengths in quiet. In both quiet and noise backgrounds, CLIN procedures were much more efficient than 2IFC procedures.

Acknowledgments
Susan Carpenter collected the data for this study and did some of the data analyses. Marjorie Leek, Tom Buell, and two anonymous reviewers gave valuable comments on an earlier draft of this paper. This work was supported by VA-DOD research grant and Naval Medical Research and Development Work Unit 65856N-M0100.001–5001. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the U.S. Government.
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