Acoustic fields, set up in ducts carrying fluids, are modified owing to viscosity and heat conduction. These distortions are more prominent near the walls of the ducts. As a result, the field near a wall could be regarded as an acoustic boundary layer. In this paper, an account of the attenuation due to this boundary layer is presented. Included also is a discussion about the possible interacting influence of the flow boundary layer on the attenuation due to acoustic boundary layer.