  In an important class of linear viscoelastic media the stress is the
superposition of a Newtonian term and a stress relaxation term. It is assumed
that the creep compliance is a Bernstein class function, which entails that the
relaxation function is LICM. In this paper the effect of Newtonian viscosity
term on wave propagation is examined. It is shown that Newtonian viscosity
dominates over the features resulting from stress relaxation. For comparison
the effect of unbounded relaxation function is also examined. In both cases the
wave propagation speed is infinite, but the high-frequency asymptotic behavior
of attenuation is different. Various combinations of Newtonian viscosity and
relaxation functions and the corresponding creep compliances are summarized.
