The Directional Effects of Marker Frequencies on Across-Channel Temporal Gap Detection Tasks: An Experimental Study.

Introduction: Gap detection tests are crucial clinical tools for identifying auditory processing disorders that result from abnormalities in the central auditory nervous system. These tests assess the ability to resolve temporal information in sounds, which aids in the diagnosis of auditory temporal processing issues. This study explores the directional effects of marker frequencies on gap detection tasks with respect to the conditions of long and short frequency disparity (separation).

Methods: We measured the gap detection thresholds (GDTs) using four across-channel narrowband noise conditions (1-2, 2-1, 1-4, and 4-1 kHz). A within-subject study design involved 29 healthy individuals with normal hearing. Stimuli were presented monaurally using headphones routed via a calibrated audiometer.

Results: The condition with long frequency disparity and a low leading frequency (1-4 kHz) exhibited higher GDTs compared to the other across-channel conditions. However, we did not observe this effect in the other condition with long frequency disparity and a high leading frequency (4-1 kHz), which did not show significant differences from the two conditions with short frequency disparity.

Conclusion: The study findings suggest that the combined effects of the spectral characteristics of the gap markers, including frequency disparity and order of presentation, influence the temporal resolution ability of auditory gap detection. Clinicians evaluating a patient suspected to have central auditory disorders should recognize that the across-channel GDTs may not consistently increase as the frequency separation between the markers increases.