Date of Completion

7-30-2015

Embargo Period

7-29-2017

Keywords

Audiology, Gap Detection, Electrophysiology, Evoked Potentials, N1-P2, Clinical, Decrement in Noise Test, DeNT

Major Advisor

Frank Musiek, PhD

Co-Major Advisor

Kathleen Cienkowski, PhD

Associate Advisor

Leslie Bernstein, PhD

Associate Advisor

Shannon Palmer, AuD, PhD

Associate Advisor

Jeffrey Weihing, PhD

Field of Study

Speech, Language, and Hearing Sciences

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Objective: The purpose of this study was to evaluate a partially filled gap detection procedure, the Decrement in Noise Test (DeNT), for the assessment of temporal resolution and estimation of auditory “temporal window” parameters. The procedure was compared to a “gold-standard” psychophysical technique, a two-interval, two-alternative forced choice procedure (2I/2AFC), as well as an electrophysiological decrement detection task using the N1-P2 auditory evoked potential.

Design: The DeNT consisted of one, two or three decrements randomly placed within 150 noise trials. The decrements had a depth that corresponded to 0% (i.e., false alarm trials), 25%, 50%, 75% or 100% (i.e., full gap) and a duration that ranged from two to 20 ms, with six instances of each depth-duration combination (5 decrement depths X 10 decrement durations X 6 repetitions).

Results & Discussion: The DeNT was administered to 35 normal-hearing female college students with no reported history of otologic or neurological dysfunction. It took approximately 20 minutes per ear to administer. When “hit-rate” was used as the only threshold criterion, decrement duration thresholds were 5.8 ms for 100% decrements, 6.6 ms for 75% decrements and 10.6 ms for 50% decrements. None of the participants tested were able to reach a criterion performance of 67% (i.e., four out of six decrements) for the 25% decrement depth. Performance was also expressed in terms of d’ because the DeNT incorporates both a hit rate and a false alarm rate. When a d’ of 0.78 (i.e., 71% correct performance) was used as the criterion, estimates of threshold were reduced by half as compared to those derived from hit-rate alone. Those reduced thresholds were consistent with those obtained using the 2I/2AFC task. Electrophysiological gap detection was consistent with previous EP gap detection studies and demonstrated a trend of increased N1-P2 amplitude and a significantly larger signal-to-noise ratio as the magnitude of the decrement is increased.

Conclusions: The DeNT procedure can be used to evaluate temporal resolution. Future studies will evaluate the validity and the sensitivity of the DeNT to lesions of the central auditory nervous system.

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