This chapter provides a framework and roadmap for the book. It starts with a brief history of underwater acoustics from the time of the Greek philosopher Aristotle (384–322 BC) up to the post–World War II era. This is followed by a discussion of the international system of units used in the book and a discussion on the use of the decibel scale. Next, the chapter deals with the features of oceanography including sound speed profiles, thermoclines, arctic regions, deep isothermal layers, expressions for the speed of sound, surface waves, internal waves, bubbles from wave breaking, ocean acidification, deep-ocean hydrothermal flows, eddies, fronts and large-scale turbulence, and diurnal and seasonal changes. This is followed by a discussion of the sonar equation that is fundamental to underwater acoustics.
Bjørnø L. & Buckingham M. J., 2017. General characteristics of the underwater environment. In: Neighbors T. H., III & Bradley D. (Eds.), Applied Underwater Acoustics, pp 1-84. Elsevier, Amsterdam. Chapter (restricted access).
