Underwater acoustic ambient noise levels on the eastern Canadian continental shelf

Abstract

This paper reports the analysis of shallow-water ambient noise levels collected by Defence Research Establishment Atlantic during 14 cruises over the period 1972 to 1985. A weighted average is formed to de-bias the samples, with the aim of answering the question: ‘‘If one were to pick a site randomly on the eastern Canadian continental shelf at a random time, and perform an ambient noise measurement, what would be the expected noise level?’’ The samples are also grouped according to whether they were taken on the Scotian Shelf, the Grand Banks, or the Flemish Cap, and according to season. The frequency range covered is 30 to 900 Hz. The weighted mean and standard deviation of the noise levels are presented, as well as the correlation coefficient between the noise levels and wind speed. The results show that the eastern Canadian continental shelf as a whole presents levels that are characteristic of areas with high shipping density and good acoustic propagation, with the Scotian Shelf showing generally higher ambient noise levels. Finally, a comparison with Piggott’s ambient noise measurements [C. L. Piggott, ‘‘Ambient sea noise at low frequency in shallow water of the Scotian Shelf,’’ J. Acoust. Soc. Am. 36, 2152–2163 (1964)] on the Scotian Shelf is made, and an explanation for the observed difference is suggested.