The propagation of short acoustical pulses in lossy media is presented as a time-varying transfer function (or spatial filter) that acts on the spatial spectrum of the source excitation. The source is a planar source of arbitrary (but separable) spatial and temporal dependence mounted in a rigid baffle. The homogeneous medium obeys Stokes' equation, resulting in a quadratic dependence of the plane-wave attenuation coefficient. Using distribution theory, an integral expression for the field is derived in terms of the normal velocity of the source, the Green's function, and its normal derivative on the boundary. This expression leads to an approximate solution for a point source in the source plane, which in turn produces a spatial transform that is the propagation transfer function. This transfer function is simply related to the transfer function of lossless propagation. Computer simulations of fields as well as a discussion of some casuality problems introduced by the use of the Stokes' equation are presented.