Integration of auditory input with vestibular and neck proprioceptive information in the interpretation of dynamic sound localization cues

Abstract

In order to measure the extent to which vestibular and proprioceptive cues influence processing of dynamic sound localization cues resulting from head rotation, we measured in passive, active, and counter rotation conditions, the ability of normally hearing listeners to localize front/rear sources of low-frequency sounds that typically cannot be accurately localized without head motion. These targets were presented during head rotations and were gated on/off as the head moved through a variable-width spatial window. In the passive condition, information about rotation carried by efference copy was minimized by passively rotating the listener's body with no neck movement, while the subject actively moved their own head on body in the active condition in order to measure for vestibular influence. The proprioceptive input from the neck was isolated by counter-rotating the body relative to the stationary head-in-space in the counter condition, which minimized vestibular input. Performance improved monotonically with increasing spatial window width but decreased as head velocity increased in both passive and active conditions while performance was near chance in the counter condition. These results suggest that among the two sensorimotor cues (vestibular and proprioceptive), only the vestibular inputs are necessary and sufficient to inform the auditory system about head movement.