On the use of click-evoked electric brainstem responses in audiological diagnosis. II. The influence of sex and age upon the normal response.
Brain stem electric responses (BSER) to clicks at 80, 60 and 40 dB SL (rate 22.5/sec) were recorded from 62 normally hearing subjects grouped according to sex and age. There were four groups: young females (mean age 26.8 years), old females (56.1 years), young males (29.6 years), and old males (59.3 years). The BSERs were measured in respect to peak latencies (I, III, V) and interpeak intervals (I-III, III-V, I-V). Wave replicability was seen to deteriorate with age. Concerning peak, latencies, highly significant differences were established between the group of young females on the one hand, and the other three groups on the other, young females exhibiting shorter latencies (of the order of 0.2 msec); differences between the other three groups were less significant or not significant at all. Concerning interpeak intervals, the differences between groups showed little or no significance. Furthermore, in old subjects--but not in young ones--the individual III-V interval exhibited a significant increase with reduction of click intensity from 80 to 60 dB SL of the order of 0.1 msec. Variances of peak latency and interpeak interval measures were not seen to differ significantly between groups.