Association between the Right-ear Advantage for Dichotic Listening Tasks and Speech Perception in Adults: The Influence of Auditory and Nonauditory Factors

It has been extensively documented that the right ear is more sensitive than the left ear in processing complex sounds such as speech. The term right-ear advantage (REA) has been used to refer to such higher right ear sensitivity, especially in dichotic listening tasks. It has been shown that the REA increases with age. This may indicate that an asymmetry between the right and left ear pathway increases with the age, having important consequences for speech perception and therefore for hearing aid benefit in older adults. However, a REA may increase due to nonauditory factors such as attention and working memory. In this research we investigated the magnitude of the REA in a cohort of 80 adults aged between 20 and 84 years with the aim to determine (a) the association between the magnitude of the REA and speech perception (in both quiet and noise), and (b) auditory and nonauditory factors associated with the magnitude of the REA in adults. The REA was evaluated with a number of procedures including double, and triple dichotic digits as well as with dichotic words. Ear asymmetries were evaluated with otoacoustic emissions and auditory brainstem responses. Speech perception was evaluated with procedures such as the hearing-in-noise test, matrix test, filtered speech and compressed speech. Finally, cognition was evaluated with procedures investigating sustained attention, working memory and executive function. The results showed that the magnitude of the REA is significantly associated with performance for speech perception tasks. Multivariate regression models showed that cognitive and auditory factors were associated with the magnitude of the REA. Auditory factors were mainly associated with the left ear performance for dichotic listening and speech perception tasks, especially in older adults. A discussion of the clinical applications of these results, especially for hearing aid fitting in older adults will be addressed. Funding source: FONDECYT 1151502 (CONICYT, Chile)