The results of an experimental and theoretical study of the form of the distribution-density function for acoustic-emission (AE) signal amplitudes at different material-destruction stages are described. On the basis of the Poisson model of the flaw-generation process, the theoretical form of the density of the acoustic-emission amplitude distribution during destruction of a solid is obtained. The conditions for the appearance and location of false amplitude maxima, which strongly reduce the reliability of the results from diagnostics of the prefracture state, are evaluated on the basis of the AE-amplitude distribution profile.