The calculation of acoustic indices derived from long-duration recordings of the natural environment

The work described in this technical report is part of ongoing research within the QUT Ecoacoustics Research Group to build practical tools for the manipulation, analysis and visualisation of recordings of the natural environment. This report describes methods we use to calculate spectral and summary acoustic indices derived from recordings of the environment. A spectral index is a vector of N values, one for each frequency bin of the spectrogram. A summary index is a scalar value, in some cases derived directly from the waveform envelope and in other cases from the corresponding spectral index.