Source signature characterization and detection of open-circuit SCUBA regulators

A goal of the Center for Island, Maritime, and Extreme Environment Security is to develop passive acoustic methods to monitor harbor and near-shore environments. To study detection of open circuit SCUBA divers, several regulator configurations were recorded and characterized under ideal conditions in a pool environment. Sound Pressure Levels (SPL) and Sound Spectral Levels were calculated over the 300 Hz to 80 kHz band. Preliminary results include SPL range over selected recordings. Regulator broad-band signatures were used to test detection algorithms under varying synthetic and real ambient noise conditions. The first detector is an envelope detector exploiting a priori knowledge of the underlying signal length, corresponding to the divers's fundamental breathing frequency and require at least two breaths for a positive result. In order to maximize signal to noise ratio (SNR), regulator signatures were band-pass filtered to exploit their respective dominant features. Receiver operating characteristic cu...