Three experiments compared auditory temporal acuity in humans and in the behavior and single cells in the inferior colliculus (IC) of mice, to establish the comparability of aging effects on temporal acuity across species, and to suggest a neural foundation. The thresholds for silent gaps placed in white noise (MGTs) were similar in young mice and young humans, and increased in some but not all old humans and old mice. Neural MGT in the most sensitive cells of both young and old mice was comparable to behavioral MGT in the young of both species, but older mice had more cells with very high MGT. Human listeners were selected to have minimal absolute hearing loss. Older mice had significant hearing loss that was correlated with MGT in behavioral, but not in neural, measures. Some old mice and some old IC cells, however, had low MGTs coupled with elevated absolute hearing thresholds. Age-related changes in temporal acuity appear comparable in humans and mice. The data suggest a common deficit in neural mechanisms.