Mid frequency shallow water fine-grained sediment attenuation measurements.

摘要: Attenuation is perhaps the most difficult sediment acoustic property to measure, but arguably one of important for predicting passive and active sonar performance. Measurement techniques can be separated into “direct” measurements (e.g., via probes, cores, laboratory studies on “ideal” sediments) which are typically at high frequencies, O(104–105) Hz, “indirect” where attenuation inferred from long-range propagation or reflection data, generally O(102–103) Hz. A frequency gap in exists 600–4000 Hz band also a general acknowledgement that much historical fine-grained sediments have been biased due non-negligible silt sand component. shallow water measurement technique using long range reverberation critically explored. An approximate solution derived energy flux theory shows very sensitive depth-integrated layer separable other unknown geoacoustic parameters. Simulation Bayesian methods confirms theory. Reverberation across 10 m yield an 0.009 dB/m/kHz with 95% confidence bounds 0.006–0.013 dB/m/kHz. This among lowest values reported water.