Subthreshold Vestibular Stimulation as a Strategy for Rehabilitation

Inclusion Criteria for Bilateral Vestibular Hypofunction:

1\. Bilateral lateral canal VOR gain of \< 0.8 on video head impulse testing OR bilateral positive bedside head impulse test

Inclusion Criteria for Unilateral Vestibular Hypofunction:

1\. Unilateral yaw aVOR gain of \< 0.8 on video head impulse testing OR unilateral positive bedside head impulse test

Inclusion Criteria for all Participants:

1. Must be able to stand for 5 minutes unassisted
2. No leg or foot amputations
3. No lower limb braces
4. Not currently pregnant by self-report
5. Weight \<= 300 pounds (due to limitations of testing equipment)

Exclusion Criteria for all participants:

1. Severe head trauma or traumatic brain injury
2. History of seizures
3. Alternative neurologic illness or condition known to impact vestibular or balance function (e.g., stroke, neurodegenerative disorders, demyelinating illness)
4. Major psychiatric (e.g., panic disorder, psychosis, etc.) disorder
5. Any of the following eye diseases or conditions: amblyopia (or "lazy eye") or history of amblyopia, diagnosis of age- related macular degeneration, retina dystrophy, glaucoma, cataracts,
6. Recent (\<6 months) orthopedic injury that may affect test performance
7. Recent surgery (\< 6 months) that may impact test performance.
8. Other severe health problems (heart disease, pulmonary disease, cancer, etc.) that may affect test performance
9. Due to potentially nauseogenic nature of some motions and to protect fetus and mother, pregnant women will also be excluded from this study

   * Since the investigators cannot address every possible potential individual recruit in advance, additional exclusion criteria may be required.