Participants will complete a training protocol that includes half roll tilt and half inter-aural translation. The training stimulus parameters are as follows: 0.5 Hz inter-aural translation motion and 0.5Hz roll tilt, stimulus size will be adjusted based upon subject responses using 2-down, 1-up (2D/1U) staircases, and both auditory and visual feedback will be provided. The training protocol will be completed first, followed by the placebo intervention.

Participants will complete a training protocol that includes half roll tilt and half inter-aural translation. The training stimulus parameters are as follows: 0.5 Hz inter-aural translation motion and 0.5 Hz roll tilt, stimulus size will be adjusted based upon subject responses using 2D/1U staircases, and auditory and visual feedback will be provided. The placebo intervention will be completed first, followed by the training intervention.

The participants will be translated and asked to indicate their perceived direction of self-motion (e.g., left or right). Feedback will be provided to promote learning (i.e., improved perception of motion). Feedback will only be provided after the subject responds, and thus vestibular (i.e., self-motion) perception is required to judge the direction of the translation stimulus. After each trial, a three second period of rest will be given. Each day of training will include four blocks of one hundred trials each. Testing will take place in the dark (except for aims where a visual cue is provided). Subjects will be seated on a motion platform with a 5-point harness and the head restrained. Insert earbuds (along with a white noise signal) will be used to reduce external noise. Subjects will always be asked to make a decision (e.g. left versus right) by pressing buttons with their left or right hands. If not certain, subjects are instructed to provide their best guess.

The participants will be equally tilted and translated and asked to indicate their perceived direction of self-motion (e.g., left or right) . Feedback will be provided to promote learning (i.e., improved perception of motion). Feedback will only be provided after the subject responds. After each trial, a three second period of rest will be given. Each day of training will include four blocks; 2 blocks of roll tilt and 2 blocks of translation - one hundred trials each. Testing will take place in the dark (except for aims where a visual cue is provided). Subjects will be seated on a motion platform with a 5-point harness and the head restrained. Insert earbuds (along with a white noise signal) will be used to reduce external noise. Subjects will always be asked to make a decision (e.g. left versus right) by pressing buttons with their left or right hands. If not certain, subjects are instructed to provide their best guess.

Participants will complete home-based exercises that are not associated with improving vestibular perception or balance (e.g. saccades, smooth pursuit). Participants will sit in a comfortable chair facing out into a living space. They will then find a stationary object to the right and to the left of themselves as well as above and below their line of sight. Without moving their heads, they will look back and forth and up and down between the objects. Participants will complete a total of 400 eye motions per day for six days.

The Sensory Organization Test (SOT) is a standard clinical and research assessment used to quantify quiet stance postural sway in the presence of unreliable visual and proprioceptive feedback. The conditions of the test include (1) eyes open firm surface, 2) eyes closed firm surface, 3) sway referenced vision firm surface, 4) eyes open sway referenced platform, 5) eyes closed sway referenced platform, 6) sway referenced visual surround and platform. Sway-referencing describes a technique used to alter the reliability of proprioceptive and/or visual inputs by tilting the support surface or visual surround to follow the displacement of the CoP. Center of pressure data will be collected in each condition using a tri-axial force plate; each condition will be repeated three times, for 20 seconds each. The root mean square displacement (RMSD) of the CoP will be calculated for each trial, using the median of three trials as the primary outcome.

Our perturbed balance test is a research assessment that we have developed to quantify postural sway in response to motion perturbations of the support surface. Vision will always be occluded (e.g., blindfolded). Forces and torques at the support surface will be quantified. Each trial will take about four minutes to complete and will be repeated three times. The root mean square displacement (RMSD) of the center of pressure (CoP) will be calculated for each trial, as will the gain at each perturbation frequency, using the median of three trials as the outcome variable.

Static stance will be measured using a tri-axial force plate; postural sway will be measured in response to balance challenges including: (1) standing either on a foam or firm surface, (2) with the eyes either open or closed, and (3) with the feet together or in tandem. The ability to complete the test (i.e., without a loss of balance) will be recorded.

Inertial measurement units (IMUs) will be used to collect motion data to quantify spatiotemporal characteristics of gait (i.e. gait velocity, single/double support time, step length, step width, stride length). Participants will wear noise-cancelling headphones that also provide 65 dB SPL of broadband, auditory noise to remove the contributions of environmental auditory feedback. Each participant will walk at a self-selected pace along a straight 117-foot path. They will make an 180° turn at each end and continue to walk for 6 minutes. IMUs will be placed on each ankle, the lumbar spine, neck, and head. The IMUs on the ankles will be used to detect heel-strike and toe-off, so that a custom MATLAB script will quantify the means and variability of each spatiotemporal characteristic of interest. Measurements will include both means and standard deviations of each parameter.