Daily rhythm of temporal resolution in the auditory system

Over a period of 24 hours, fusion thresholds (click durations 100 mu s) wer e assessed in 7 subjects. Over the same period, order thresholds (click dur ation of 1 ms) were measured in 10 subjects (12 independent sessions). Audi tory fusion thresholds showed a diurnal rhythm with a maximum performance ( shortest intervals) around midnight. In contrast, order thresholds appear t o be independent on the time of day. Sex specific differences in threshold levels were only observed in order thresholds but not in fusion thresholds.