The Where and When of Tracking Sound Sources Head-based auditory motion tracking integrates velocity and spatial error within a common delayed frame

Auditory objects in everyday environments remain seldomly at the same position but move about in the environment and keeping track of their motion is an essential task for the auditory system to maintain a correct representation of auditory space/scene. Following such a moving sound source in two-dimensional space requires the nervous system to guide head movements using delayed and uncertain sensory information. How the auditory system integrates such information for combined horizontal and vertical movements is still debated. 116 117 We recorded head movements from 14 participants tracking a physically moving loudspeaker along unpredictable two-dimensional trajectories. Participants followed source motion with substantial delays and retained measurable spatial discrepancies. To explain these behaviours, we developed a hybrid model combining source velocity with the spatial discrepancy between source and head at the matched, delayed time points. The model predicts head velocity on previously unseen trajectories more accurately than formulations relying on either signal alone. Importantly, using preceding rather than current head orientation improved prediction, highlighting the importance of temporal correspondence between sensory and motor states. These findings suggest that head-based auditory motion tracking depends on complementary motion and spatial information represented within a common delayed reference frame.