Parametric modeling and estimation of acoustic sediment properties using a system identification approach

The acoustic properties of marine sediments are measured to obtain an acoustic signature of their mechanical characteristics. The proposed 1-D wave propagation model accounts for absorption and dispersion. Use is made of an inverse procedure based on a maximum likelihood estimator for obtaining a parametric identification of the sediments. Measurements are performed in the laboratory, in reflection and transmission modes, on prepared samples of natural sediments, at normal incidence, and using a controlled measurement environment in the frequency range of 300 to 700 kHz. The model validation is performed for a water layer, an ideal medium with little absorption and dispersion, and for a silty-clay layer. A comparison between the estimated and measured amplitude and phase characteristics for these two media indicates that the parametric identification of the silty-clay is successful. For both media, comparable differences, of 0.3 dB maximum for the amplitude and three degrees for the phase, are observed.