Intrasubject variability in the absolute latency of the auditory brainstem response.

For many applications, the latency of obtained ABR peaks is compared to clinical norms. Using this approach, one presupposes that basic assumptions regarding inter- and intrasubject variability of latency are met. Although much is known about intersubject variability, virtually nothing has been reported about intrasubject variability. The purpose of this investigation was to describe intrasubject variability of ABR latency as observed in a clinical setting. Nine male subjects, 10 to 12 years old, participated in the study. At each of four sessions, five ABRs were obtained for each of three stimulus conditions. Stimuli were 100 microseconds condensation clicks presented at 80 dB nHL. For each ABR peak, the intrasubject distribution of latencies was analyzed. For every subject, variability of latency was observed. Typically, the latencies were normally distributed, and the magnitude of variability was less than is commonly reported for groups of subjects. We conclude that by establishing a baseline, the sensitivity of the ABR might be increased for certain monitoring applications.