Effects of auditory injury on binaural listening in service members with normal hearing thresholds
Recent studies have shown that noise exposures that produce temporary threshold shifts (TTS) can temporarily degrade NoSpi tone-in-noise detection, and that individuals who report frequent auditory symptoms after noise exposure often experience increased hearing difficulties and chronic degradations in both NoSo and NoSpi tone-in-noise detection despite having hearing thresholds in the normal range. The present study used data from two groups of Service Members (SMs) to determine whether these effects extended to speech-in-noise performance. Both groups of SMs completed a speech-in-noise test, pure-tone audiometry, and a questionnaire about TTS history. The first sample completed a version of the Modified Rhyme Test (MRT) with monaural, diotic, and binaural listening conditions in speech-shaped noise. The second completed the Spatial Digit Test (SDT), a test that requires listeners to use differences in interaural timing cues to segregate two simultaneous digits. SMs with a history of frequent TTS performed worse on both speech-in-noise and speech-on-speech masking tasks. However, the results did not provide strong evidence that TTS impairs binaural listening more than monaural listening. [The views expressed in this presentation are those of the authors and do not necessarily reflect the official policy of the Department of War or the U.S. Government.]