The high frequency environmental acoustics sediment model in the light of recent advances

The high frequency environmental acoustics sediment model (HFEVA) published in the High-Frequency Ocean Environmental Acoustic Models Handbook (APL-UW 9407), which has been widely adopted by underwater acousticians and sonar modelers, is examined in the light of recent sediment acoustic models and measurements, particularly the multiple scattering and poro-elastic models. The former indicates that the sound speeds and attenuations for the larger grain sizes (phi < -1) need to be updated, and the latter that the sediment densities for the middle range of grain sizes (1 < phi < 5) are underestimated. On the last point, the authors of the original model were aware of the problem, and for practical reasons decided to accept the understatement in the interests of achieving the correct reflection loss. The discrepancies may be alleviated by adopting a poro-elastic model with multiple scattering corrections. For practical applications, an efficient parameterization of the poro-elastic model allows the number of adjustable parameters to be reduced to a level comparable with that of simpler fluid and elastic models, while retaining all its physical advantages. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]