Wind noise source level and Bio-Goose: Perspectives on Doug Cato’s contributions in ocean ambient noise

Abstract

Doug Cato’s research has provided insights that form the basis of our understanding of ambient noise in the ocean. This paper focuses on only two aspects of ambient noise that are strongly linked to Doug’s work. One is source level of ambient sound due to local wind at the sea surface. Estimates of wind sound source level derived from noise measurements with vertical line hydrophone arrays are shown to be consistent with the levels for noise due to wind reported in the Cato curves—up to date relationships for levels of components of ambient noise over a wide frequency band. The second aspect revisits a curious sound that was recorded in waters around Australia and New Zealand some years ago. The sounds were believed to be generated by marine animals, but the type of creature was not identified at sea or in subsequent analysis. Owing to the limited bandwidth of the recordings, the sound was accordingly dubbed as Bio-Duck in New Zealand and Bio-Goose in Australia. Further characteristics of the sound are presented, along with evidence of a probable conversation between two speakers and an example of the Lombard effect in the communications.