Frequency dependence of sediment attenuation in two low-frequency shallow-water acoustic experimental data sets

Shallow-water transmission loss measurements taken in 1988 and 1993 along the same cross slope track on the New Jersey shelf are examined for the frequency interval 50-1000 Hz. Computed results, using a geoacoustic model based on a linear frequency dependence of the sediment volume attenuation, showed less loss than the measured data at the higher frequencies. A two stage, least squares procedure, is developed as a means of quantitatively examining the differences between the measured and computed results. The procedure focuses on the frequency dependence of the sediment volume attenuation and allows the comparison between measurements and computations to be formulated as a statistical test of hypothesis. A geoacoustic model, using a nonlinear frequency dependency and reasonable uncertainty for the sediment volume attenuation, provides a good fit to the data.