The effect of auditory cues on heading direction during stepping-in-place in healthy adults with experimentally induced vestibular asymmetry.

Visual, vestibular, and proprioceptive cues are known to influence the orientation of our body in space. Auditory cues also influence spatial orientation, as recent studies shown they affect static postural balance. However, the influence of auditory stimulation on dynamic postural balance tasks, such as heading direction during vestibular perturbation, remains understudied. To examine the influence of auditory cues on heading direction during a stepping-in-place task with and without galvanic vestibular stimulation (GVS). Twenty young healthy participants performed a stepping-in-place task, blindfolded with the head tilted forward to produce a GVS-evoked yaw rotation signal, with instructions to maintain the starting body position/orientation. The task was repeated under two auditory conditions (no sound or with sound) and three vestibular conditions (NoGVS, anode left, and anode right). Participants were divided equally according to instructions regarding the sound source position. Pelvis angular deviation relative to the sound source was measured using motion capture. The angular deviation error at the end of the trial and its variability with and without sound were calculated and analysed. Without GVS, auditory cues failed to reduce the angular deviation error of the pelvis rotation and its variability. Additionally, left and right GVS significantly increased pelvis angular deviation toward the anodal side compared to NoGVS. However, GVS-induced angular deviation did not differ with and without sound. Even though vestibular cues have been shown to significantly contribute to orientation in the absence of vision, auditory cues could not help maintaining heading direction during a stepping-in-place task, both under normal conditions and following acute vestibular perturbation.