Impact of Unilateral Hearing Loss on Behavioral and Evoked Potential Measures of Auditory Function in Adults.

Abstract

BACKGROUND:A unilateral hearing loss (UHL) can have a significant functional and social impact on children and adults, affecting their quality of life. In adults, UHL is typically associated with difficulties understanding speech in noise and sound localization, and UHL increases the self-perception of auditory disability for a range of listening situations. Furthermore, despite evidence for the negative effects of reduced unilateral auditory input on the neural encoding of binaural cues, the perceptual consequences of these changes are still not well understood. PURPOSE:Determine effects of UHL on auditory abilities and speech-evoked cortical auditory evoked potentials (CAEPs). RESEARCH DESIGN:CAEPs, sound localization, speech perception in noise and self-perception of auditory abilities (speech, spatial, and qualities hearing scale) were assessed. STUDY SAMPLE:Thirteen adults with UHL with a range of etiologies, duration of hearing loss, and severity and a control group of eleven binaural listeners with normal hearing. RESULTS:Participants with UHL varied greatly in their ability to localize sound and reported speech recognition and listening effort were the greatest problem. There was a greater effect of right ear than left ear hearing loss on N1 amplitude hemispheric asymmetry and N1 latencies evoked by speech syllables in noise. As duration of hearing loss increased, contralateral dominance (N1 amplitude asymmetry) decreased. N1 amplitudes correlated with speech scores, larger N1 amplitudes were associated with better speech recognition in noise scores. N1 latencies are delayed (in the better ear) and amplitude hemisphere asymmetry differed across UHL participants as function of side of deafness, mainly for right-sided deafness. CONCLUSION:UHL affects a range of auditory abilities, including speech detection in noise, sound localization, and self-perceived hearing disability. CAEPs elicited by speech sounds are sensitive enough to evidence changes within the auditory cortex due to an UHL.