Estimation of sea floor properties using acoustic vector sensors

Abstract

Information in the acoustic vector field can be used to estimate properties of the environment with which the field interacts. A study was performed to understand the value of vector field data when inverting for sea floor geoacoustic properties. The study compared results obtained with new inverse methods based on measurements of complex acoustic transfer functions and specific acoustic impedance. Acoustic field data consisted of gated continuous wave transmissions acquired with four acoustic vector sensors that spanned the water-sediment interface during the Sediment Acoustics Experiment 2004 (SAX04). Motion data provided by the buried vector sensors were affected by a suspension response that was sensitive to the sediment density and shear wave speed. The suspension response for the buried vector sensors included a resonance within the analysis band of 0.6–2.4 kHz. The response was sufficiently sensitive to the local geoacoustic properties, that it was exploited by the inverse methods developed for this study. Inversions of real and synthetic data sets indicated that information about sediment shear wave speed was carried by the suspension response of the buried sensors, as opposed to being contained inherently within the acoustic vector field. [Work supported by ONR.]