Individual variation in sound localization accuracy is correlated with the properties of eye movement-related eardrum oscillations (EMREOs)

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 sound localization (here, saccades to sounds) even in normal individuals: median horizontal errors ranged from 2-6{degrees}, and median vertical errors could be as large as 36{degrees}. We separated the subject pool into groups with "good" performance (median vectorial error < 8{degrees}) vs "poor" performance (median vectorial error > 10{degrees}) and evaluated their respective EMREOs. The EMREOs differed across the two groups in both horizontal and vertical dimensions, in how saccade amplitude vs. initial eye position was encoded, and across time with respect to the saccade. These results are consistent with the interpretation that EMREOs are associated with underlying processes that ensure the accuracy of sound localization. HIGHLIGHTSO_LIThe accuracy of eye movements to look at sounds varied across individuals, with median errors spanning a greater than 10-fold range. This range is surprising given that the participants passed screening for normal hearing. C_LIO_LI"Good" vs "poor" sound localizers exhibited differences in their eye movement-related eardrum oscillations (EMREOs) C_LIO_LIEMREOs differed in both horizontal and vertical sensitivity, for both saccade amplitude and initial eye position, and the differences varied in timing with respect to saccade onset. C_LIO_LIWe interpret the results under the theory that poor sound localization may be a consequence of poor eye movement encoding, without which linking visual and auditory space is likely inaccurate. C_LI