Dear MARMAMers, those of you involved in passive acoustic monitoring may be interested in our recent paper on performance assessment of PAM devices and statistical characteristics of noise levels: Spectral probability density as a tool for ambient noise analysis Nathan D. Merchant, Tim R. Barton, Paul M. Thompson, Enrico Pirotta, D. Tom Dakin, and John Dorocicz, J. Acoust. Soc. Am. 133, EL262-EL267 (2013) Abstract This paper presents the empirical probability density of the power spectral density as a tool to assess the field performance of passive acoustic monitoring systems and the statistical distribution of underwater noise levels across the frequency spectrum. Using example datasets, it is shown that this method can reveal limitations such as persistent tonal components and insufficient dynamic range, which may be undetected by conventional techniques. The method is then combined with spectral averages and percentiles, which illustrates how the underlying noise level distributions influence these metrics. This combined approach is proposed as a standard, integrative presentation of ambient noise spectra. The paper is open-access and can be downloaded free here: http://dx.doi.org/10.1121/1.4794934 Kind regards, Nathan Merchant -- Nathan Merchant PhD Researcher Department of Physics University of Bath BA2 7AY, UK +44 1225 385543 n.d.merchant@bath.ac.uk http://people.bath.ac.uk/ndm23/