Acoustic characterization of the Odyssey II autonomous underwater vehicles

Acoustic testing was conducted to characterize the self-noise state of the Odyssey II class autonomous underwater vehicles (AUVs). The tests were conducted at the Naval Undersea Warfare Center Division Newport with additional personnel from the Massachusetts Institute of Technology and from Ocean Acoustical Services and Instrumentation Systems. Measurements of sound pressure and structural acceleration were made at various points on the interior and exterior of a vehicle while it exercised actuators in a manner representative of actual operating conditions. The resultant data identify the major noise contributors and transmission paths within the AUV. Sound pressure levels measured at locations proposed for acoustic communication hydrophones allow calculation of the source levels required to receive signals from various ranges. The effects of hull transmission loss and spatial differences within the vehicle are quantified. Potential design modifications are proposed to improve self-noise levels. Areas which require further testing are defined.