The sound pressure time series received at medium ranges from small underwater explosives, known as “SUS” charges, have been under close study in recent years in relation to the potential impact of the use of such devices on marine fauna, in particular, marine mammals. Past work has centred on investigations of time series measured in shallow oceans in the Australian region. Here, at-sea measured data showed, consistently, received peak levels which were considerably less than published weak shock theory would have suggested. This paper shows the results from the analysis of an extended data set, which includes measurements of SUS signals received along a shallow ocean track in an additional ocean region. Further, this paper shows the results of simulations of the time series received along all these tracks. These simulations of received SUS waveforms, carried out at Curtin University, have been obtained by generating an inverse Fourier transform of the product of the oceanic transfer function and the Fourier transform of an input SUS waveform. The oceanic transfer function has been based on the use of the SCOOTER model at low frequencies and a ray model (BELLHOP gaussian beam ray model) at remaining frequencies. By simulating the received time series in this way, reasons for the discrepancies between measured peak data and expectations based on weak shock theory have been investigated and are presented in this paper.

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