Optimizing masker phase effects for use in a portable hearing screening tool

Abstract

The current study is a continuation of work toward development of a preclinical indicator for noise induced hearing loss. Masked threshold differences produced by Schroeder-phase maskers have been demonstrated with long duration tones at different frequencies (1, 2, and 4 kHz) as well as with IEEE sentences (Summers and Leek, 1998) for normal hearing listeners, but these differences are not found for hearing impaired listeners. Similar results are also found for repeated short duration tone bursts and greater differences occur with systematically changed tone burst frequencies (Hoglund et al., 2012). Using the enhanced channel model (Oh, 2013), threshold differences are predicted, and the Schroeder-phase masker characteristics are adjusted to maximize the difference. This leads to a greater range of masker phase effect differences between the positive and negative Schroeder-phase maskers, and should allow greater sensitivity to preclinical hearing threshold changes. These optimized maskers were also applied to a digit triplets test designed for telephone hearing screening (Watson et al., 2012). Testing with both the digit triplets and the short duration tone bursts are compared for ease of use and portability, as well as sensitivity to small changes in post-exposure thresholds. [Work supported by the Office of Naval Research.]