Infauna dwell in the benthic zone and have the capacity to modify the physical and acoustic properties of the seabed through bioturbation. To investigate such effects, in situ measurements of compressional and shear wave speed and attenuation were conducted in Petit Bois Pass, near the mouth of Mobile Bay, Alabama, USA. The measurement system was deployed at multiple locations within the pass, and acoustic measurements were conducted at depths up to 20 cm into the sediment to scan the portion of the seabed where most infauna live. Additionally, diver cores were collected and analyzed for infauna abundance and geotechnical properties, such as porosity and grain size distribution, for comparison with the acoustic data. While sediment geoacoustic models do not explicitly account for effects of biology, they do allow for parameterization of various physical properties like porosity, grain size, or pore fluid viscosity, all of which can be modified by the presence of biological organisms and bioturbation. Results from the in situ acoustic measurements and core analysis will be compared with such models to determine if any additional insight into the acoustic effects of infauna can be gained. [Work supported by ONR and ARL:UT IR&D.]