Effects of Hearing Loss on Interaural Time Difference Discrimination in an Oddball Paradigm

For individuals with hearing loss, a decline in Interaural Time Difference (ITD) discrimination ability can negatively impact daily activities. Mismatch negativity (MMN), a component of the event-related potential (ERP), can be used as an objective measure of sound feature (such as ITD) discrimination accuracy. A unified experimental paradigm is necessary to establish a clear relationship between MMN and ITD discrimination. This article presents our preliminary work investigating the effects of hearing loss on ITD discrimination in an oddball paradigm, which is typically used in MMN tests. The stimuli were a white noise filtered between 125 to 8000 Hz with a duration of 60 ms. Three different degrees of hearing loss (normal, mild, moderate) were simulated using a hearing loss simulator, and four ITDs (50, 120, 200, 400 μs) were constructed by delaying the signal in the left channel. Eight college students (5 males, 3 females) with normal hearing participated in the experiment. Listeners' task was to identify the lateralized stimuli in reference to a standard stimulus at the middle-line (i.e., ITD = 0 μs). Results demonstrate significant effects of both hearing loss and ITD levels on ITD discrimination accuracy and reaction time. This study established a foundation for future ITD-MMN experiments in hearing impaired listeners by providing baseline data on ITD discrimination.