Time-of-day effects have been identified as a possible confound in research on age-related differences in cognitive performance. Circadian rhythms have been related to time-of-day variations in sensory measures; however, more is known about the effect of circadian rhythms on vision than on hearing, and virtually nothing is known about whether time-of-day effects are potential confounds in studies of auditory aging. The purpose of the current study was to determine whether age-related differences in performance on auditory tasks are affected by time of day. A set of four auditory experiments was repeated three times over the course of one day with a group of Evening-type younger adults and a group of Morning-type older adults. The results replicated previous findings of age-related differences, but time of day did not affect the basic results. Thus, time of day does not confound the results observed in typical laboratory experiments investigating auditory aging.
