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 I -D wave propagation model accounts for absorption and dispersion, Use is made of an inverse procedure based on a maximum likelihood estimato r for obtaining a parametric identification of the sediments, Measurem ents are performed in the laboratory, in reflection and transmission m odes, on prepared samples of natural sediments, at normal incidence, a nd using a controlled measurement environment in the frequency range o f 300 to 700 kHz, The model validation is performed for a water layer, an ideal medium,vith little absorption and dispersion, and for a silt y-clay layer, A comparison between the estimated and measured amplitud e and phase characteristics for these two media indicates that the par ametric identification of the silty-clay is successful. For both media , comparable differences, of 0.3 dB maximum for the amplitude and thre e degrees for the phase, are observed.