Equations for material absorption in the water column are summarized by Urick. A somewhat standard form due to Thorpe is:
where f is the frequency in kilohertz and is in units of dB/m. Attenuation in sediments is somewhat more complicated and must be specified directly.
Material absorption is included by adding an imaginary part to the sound speed so that . Typically, the attenuation is specified in more physical units so it is necessary to perform a conversion. In the following subsections we present the results for various cases.