Source levels of impulsive sound sources in underwater acoustics

Abstract

Impulsive sound sources have been used extensively in underwater acoustics for many different research applications. Since the initial work by Weston in developing a simple analytical model for an underwater explosion, there have been several theoretical and experimental programs designed to determine source levels. More recently, other types of sources such as air guns and water guns have been introduced from marine seismic research, and there is renewed interest in knowing accurate source levels for assessing the impact on marine environments. In this paper the results of a series of experiments carried out to measure the source levels of several different types of impulsive sources are summarized. These included traditional 0.82-kg SUS charges, small and medium sized air guns from 5–185 cu. in., and a 160 cu. in. water gun. The SUS charges were exploded at shot depths from 18–200 m, and the air guns and water guns were fired at shallow depths from 1–5 m, corresponding to the conventional operating depths. The experiments provided high-quality shot waveforms that were processed to determine calibrated source levels in 1/3 octave frequency bands from 10–600 Hz. The measured values are compared to predictions from Weston’s simple model.