Individual variation in the accuracy of saccades to sounds is correlated with the properties of eye movement-related eardrum oscillations (EMREOs).

Abstract

Calibration of sound localization behavior in species with mobile eyes requires not only accurate visual input but also accurate oculomotor signals across the lifespan. The recent discovery of eye movement-related eardrum oscillations suggest that oculomotor signals may be incorporated into auditory processing at the level of the ear. One inference of this discovery is that individual variation in such signals might be correlated with individual variation in sound localization accuracy. Here, we tested this hypothesis in humans with normal hearing. We discovered that there is considerable variation in the accuracy of saccades to sounds even in normal individuals: median horizontal errors ranged from 2-6 deg., and median vertical errors could be as large as 36 deg. We separated the subject pool into groups with 'good' performance (median vectorial error < 8 deg) vs 'poor' performance (median vectorial error > 10 deg) and evaluated their respective EMREOs. The EMREOs differed across the two groups in how horizontal saccade amplitude and vertical initial eye position were encoded, with considerable individual variation in the 'poor' group. These results are consistent with the interpretation that EMREOs are associated with underlying processes that ensure the accuracy of sound localization.