Sensory Integration of Auditory and Visual Cues in Diverse Contexts

More than 1/3 of adults in the United States seek medical attention for vestibular disorders and hearing loss; disorders that can triple one's fall risk and have a profound effect on one's participation in activities of daily living. Hearing loss has been shown to reduce balance performance and could be one modifiable risk factor for falls. Patients with vestibular hypofunction tend to avoid busy, hectic, visually complex, and loud environments because these environments provoke dizziness and imbalance. While the visual impact on balance is well known, less is known about the importance of sounds. In search for a possible mechanism to explain a relationship between hearing and balance control, some studies suggested that sounds may serve as an auditory anchor, providing spatial cues for balance, similar to vision. However, the majority of these studies tested healthy adults' response to sounds with blocked visuals. It is also possible that a relationship between hearing loss and balance problems is navigated via an undetected vestibular deficit. By understanding the role of auditory input in balance control, falls may be prevented in people with vestibular disorders and hearing loss. Therefore, there is a critical need for a systematic investigation of balance performance in response to simultaneous visual and auditory perturbations, similar to real-life situations. To answer this need, the investigators used recent advances in virtual reality technology and developed a Head Mounted Display (HMD) protocol of immersive environments, combining specific manipulations of visuals and sounds, including generated sounds (i.e., white noise) and real-world recorded sounds (e.g., a train approaching a station). This research will answer the following questions: (1) Are sounds used for balance and if yes, via what mechanism? (2) Do individuals with single-sided hearing loss have a balance problem even without any vestibular issues? (3) Are those with vestibular loss destabilized by sounds? To address these questions, the following specific aims will be investigated in individuals with unilateral peripheral vestibular hypofunction (n=45), individuals with single-sided deafness (n=45), and age-matched controls (n=45): Aim 1: Establish the role of generated and natural sounds in postural control in different visual environments; Aim 2: Determine the extent to which a static white noise can improve balance within a dynamic visual environment.