Influence of Variation in Sediment Conditions on the Acoustic Response of Targets near the Sea Floor

Abstract

Abstract : Detection and classification of objects on or imbedded in the ocean sediment is a problem receiving increasing attention. The measured scattering in these situations will include interactions of the incident sound with the sediment interface itself, as well as the possibility for multiple interactions between the target and sediment. This research focuses on the problem of variation in sediment properties and their effect on target responses. The long-term goals are to understand, and quantitatively predict, the effects of the environment on scattering from mines and mine-like targets. First, attempts will be made to understand the role that the interface plays on the measured scattering from proud and buried targets. Secondly, some attention will be spent on aspects pertaining to the classification of targets, specifically on understanding how the variation in scattering due to interface condition affects the classification schemes used in mine counter-measures (MCM). Ultimately, any sort of identification/classification schemes employed by the U.S. Navy will have to address two issues in order to be effective: 1) quantitative understanding of the acoustic response of objects in contact with or embedded in the ocean sediment and 2) how variation in the sediment conditions affect the acoustic response of such targets. The main objective this year aimed at identifying how various aspects of the target physics contribute to the acoustic scattering and how this is affected by the presence of the sediment. However, looking ahead to the long-term goal of understanding the role that variation in sediment plays in the acoustic scattering, the second objective was to ensure that experiments were designed and conducted that would look at the role played by the sediment properties, albeit leaving the interpretation of these results to the focus of FY11.