Beam forming of the underwater sound field from impact pile driving

Abstract

Observations of underwater noise from impact pile driving were made with a vertical line array. Previous studies [Reinhall and Dahl, J. Acoust. Soc. Am. 130, 1209–1216 (2011)] show that the dominant underwater noise from impact driving is from the Mach wave associated with the radial expansion of the pile that propagates down the pile at supersonic speed after impact. Here precise estimates of the vertical arrival angles associated with the down- and up-going Mach wave are made via beam forming, and the energy budget of the arrival structure is quantified.