Sensory gating is a mechanism that inhibits neurological responses to redundant information. Although studied within clinical populations, sensory gating has rarely been investigated with respect to aging. The present research investigated age-related changes in auditory sensory gating using electroencephalography and quantified the effect of age on adaptive gating responses for oddball stimuli. Age-related differences in sensory gating and oddball responses were observed in late-stage auditory processing, where older adults exhibited weaker sensory gating. An attenuated P200 for first and second clicks seen in the aging group may explain the weaker sensory gating ratio seen in older participants. Furthermore, replacing the second click with oddball stimuli attenuated, but did not eliminate sensory gating, indicating that sensory gating is a dynamic mechanism. Findings suggest that sensory gating is diminished for older adults and may transform from an adaptive mechanism under executive control to a pre-attentive limiter of auditory processing.