Eye movement-related eardrum oscillations do not require current visual input

Oculomotor signals influence the neural processing of auditory input. Recent studies have shown that this connection extends to the auditory periphery: The phase and amplitude of eardrum oscillations was systematically influenced by eye movement direction and magnitude, a phenomenon called eye movement-related eardrum oscillations (EMREOs). Previous findings have suggested that EMREOs occur independently from auditory stimulation, but it is unknown whether they depend on the presence of visual sensory input or solely reflect efference copies of the oculomotor system. To distinguish between these two alternatives, we measured eye movements and eardrum oscillations in sighted human participants who performed free saccadic eye movements in darkness. Despite the lack of any sensory stimulation during eye movements, significant EMREOs occurred in all participants. EMREO characteristics were comparable to a separate control experiment in which participants performed guided saccades to visual targets and were robust to different types of eye tracker calibration methods. Thus, our results suggest that EMREOs are not driven by bottom-up sensory signals but rather reflect a pure influence of oculomotor signals on peripheral auditory processing. This indicates that EMREOs might play a crucial role in reference frame transformations which are needed for audio-visual spatial integration.