When a noise arises from several individual noise events, then its equivalent continuous A-weighted sound pressure level (LAeqT) depends on the number of noise events (N), the A-weighted sound exposure levels (LAE) and the equivalent continuous A-weighted sound pressure level of the background noise (LAeqT). At least some of those quantities are random variables. Thus, the values of LAeca, measured within a constant time interval, are random as well. The results presented here make it possible to predict the mean and variance of LAeqT in terms of some characteristics of N, LAE, and LAeqT.