  This paper considers the problem of appearance indication of useful acoustic
signal in the signal/noise mixture. Various information characteristics
(information entropy, Jensen-Shannon divergence, spectral information
divergence and statistical complexity) are investigated in the context of
solving this problem. Both time and frequency domain are studied for
information entropy calculation. The effectiveness of statistical complexity is
shown in comparison with other information metrics for different levels of
added white noise. In addition analytical formulas for complexity and
disequilibrium are obtained using entropy variation in the cases of one- and
two-dimensional spectral distributions. The effectiveness of the proposed
approach is shown for different types of acoustic signals and noise level
especially when additional noise characteristics estimation is impossible.
