Year of Award


Document Type


Degree Type

Master of Science (MS)

Degree Name

Speech-Language Pathology

Department or School/College

Department of Communicative Sciences and Disorders

Committee Chair

Al Yonovitz

Commitee Members

Al Yonovitz, Catherine Off, Gregory St George


Backward Masking, Temporal masking, Clinical test of Auditory processing disorders, stimulus type


University of Montana

Subject Categories

Other Psychology


Increased backward masking has been correlated with Auditory Processing Disorders (APD). An efficacious test of the backward masking function that is compatible with naïve listeners could have clinical utility in diagnosing APDs. In order to determine an appropriate probe for such a test, three 20-ms signal-types were compared for ease-of-task. Response times (RT) were taken as a proxy for ease-of-task. Seven participants used a method-of-adjustment to track threshold in the presence of a 50-ms broadband-Gausian-noise backward-masker. The signal-types yielded two comparisons: Linear rise-fall on a 1000Hz sine-wave versus a “chirp” (750 Hz-4000Hz); Linear rise-fall vs Blackman gating function on a 1000Hz sine-wave. The results suggest that signal-type is a significant factor in participant response time and hence, confidence. Moreover, the contribution of signal-type to RT is not confounded by any potential interaction terms, such as inter-stimulus interval (ISI). The signal-type that yielded the quickest RTs across all participants, ISIs, and intensity levels was the 20-ms, 1000 Hz sine-wave fitted with a trapezoidal gating function. This may be the most efficacious signal-type to serve as a probe in a clinical test of backward masking.



© Copyright 2016 Robert David Sears