Measured acoustic scattering from a water‐filled aluminum pipe in contact with various interfaces.

Abstract

Detection and classification of objects on or imbedded in the ocean sediment are difficult problems due to the complexity of the sediment. The measured scattering will include interactions of the incident sound with the sediment interface as well as the possibility for multiple interactions between the target and sediment. Recent experiments conducted in the test pond at the Naval Surface Warfare Center, Panama City Division, investigated the impact the environment has on the measured acoustic response from various targets. A particular subset of these experiments is presented, focusing on the acoustic scattering from a water‐filled aluminum pipe having length‐to‐diameter ratio equal to 2. Initial measurements examined the scattering from the pipe in a proud configuration on the flattened sand sediment. Subsequent measurements placed the pipe in contact with interfaces with known reflection coefficients, including suspending the pipe just below the air/water interface and placing it in a proud configuration on a flat acrylic panel on the sand sediment. Acoustic templates depicting the absolute target strength as a function of azimuthal angle over the frequency range 1–30 kHz are compared for the three different configurations. [Work supported by the Office of Naval Research.]