"Dizziness, imbalance, and falls—which result in an increased burden on both patients and the healthcare system—are seen at higher rates in older, compared to younger, adults and may stem from age-related vestibular degeneration. Currently, there is a lack of diagnostic tests capable of accurately identifying the age-related changes in vestibular function that may underlie these symptoms and, therefore, older adults may experience delays in diagnosis and treatment leading to reduced quality of life and increased healthcare utilization. The objective of the present study was to investigate alternate diagnostic stimulus parameters of current vestibular tests that may be better able to effectively differentiate between healthy younger and normal-aging older adults and, therefore, better assay age-related vestibular changes. To achieve this objective, the present study employed a non-experimental, group-comparisons design including 15 younger (M = 26.7 years of age, range = 22–38) and 15 older (M = 70.0 years of age, range = 60–83) healthy adults. The three rotational vestibular tests used for between-group comparisons were: constant angular acceleration (CAA), sinusoidal harmonic acceleration (SHA), and the computerized rotational head impulse test (crHIT). Each test was completed at varying stimulus magnitudes and recorded outcomes related to vestibulo-ocular reflex (VOR) function. Results from linear mixed effects models (LMEM) analyses showed statistically significant effects related to age group for both VOR gain and phase for the SHA test but not for the CAA or crHIT tests. For SHA VOR gain, there were statically significant effects for the two-way interaction of age group (younger vs. older) and frequency (0.01 vs. 0.16 Hz) as well as the three-way interaction of age group, frequency, and velocity (60 vs. 250 deg/s). For SHA phase, there was a statistically significant effect for the two-way interaction of age group and velocity. The magnitude of the effects were qualitatively compared, following standardization of the outcome parameters, and the two-way interaction effect of age group and velocity for the SHA phase outcome was larger than either interactions for the SHA VOR gain outcome; however, fit of the LMEM examining SHA phase was poorer than that for SHA VOR gain. Results suggest that the effect of age on VOR function is apparent at high velocity and mid-frequency SHA tests. Furthermore, the magnitude of these effects are larger for SHA phase than for SHA VOR gain; however, the magnitudes are somewhat similar and LMEM fit may impede this interpretation. These findings add important information to our understanding of how VOR function is affected by age for SHA, CAA, and crHIT tests. Additionally, these results provide direction for future research, especially for studies that seek to further investigate diagnostic tests that may better elucidate age-related changes in vestibular function to help decrease the burden of dizziness, imbalance, and falls on older adults as the findings suggest that SHA presented at a high velocity and mid-frequency may elucidate the effects of age on vestibular function. "--Abstract.