In situ observation of sediment sound speed and attenuation from coarse to fine-grained sediments

Abstract

The long-term objective is to address the impact of spatial variability of sediment properties on sound propagation and reverberation from a few hundred hertz to 10 kHz. In this band, the frequency dependences of sound speed and attenuation are important for applications, but cannot be inferred from high-frequency data, hence direct measurement is necessary. In this talk, a summary of in situ measurements of sediment sound speed and attenuation collected from three major field experiments, i.e., Shallow Water 2006 (SW06), Target and Reverberation Experiment 2013 (TREX13), and Seabed Characterization Experiment 2017 (SCE17), are presented. Sediment sound speed and attenuation within the surficial 3 m of sediments were obtained through penetration, using the Sediment Acoustic-speed Measurement System (SAMS). In TREX13, i n situ measurements were carried out at five sites along a 5-km track, with sediment types ranging from coarse sand to a mixture of soft mud over sand. SAMS was deployed at 18 sites within the 10 × 30 km SCE17 study area. Significant variation of sediment geoacoustic properties was observed in range (TREX13) and depth (SCE17), respectively. Preliminary sediment acoustic modeling work is presented, using SAMS data taken from the wide range of sediment types. [Work supported by ONR.]The long-term objective is to address the impact of spatial variability of sediment properties on sound propagation and reverberation from a few hundred hertz to 10 kHz. In this band, the frequency dependences of sound speed and attenuation are important for applications, but cannot be inferred from high-frequency data, hence direct measurement is necessary. In this talk, a summary of in situ measurements of sediment sound speed and attenuation collected from three major field experiments, i.e., Shallow Water 2006 (SW06), Target and Reverberation Experiment 2013 (TREX13), and Seabed Characterization Experiment 2017 (SCE17), are presented. Sediment sound speed and attenuation within the surficial 3 m of sediments were obtained through penetration, using the Sediment Acoustic-speed Measurement System (SAMS). In TREX13, i n situ measurements were carried out at five sites along a 5-km track, with sediment types ranging from coarse sand to a mixture of soft mud over sand. SAMS was deployed at 18 sites within ...