  We study the propagation of small amplitude waves superimposed on a large
static deformation in a nonlinear viscoelastic material of differential type.
We use bulk waves and surface waves to address the questions of dissipation and
of material and geometric stability. In particular, the analysis provides
bounds on the constitutive parameters and on the pre-deformation that ensure
linearized stability in the neighbourhood of a large pre-stretch. This type of
result is relevant to the imaging of biological soft tissues using acoustical
techniques, where pre-deformation is known to increase contrast and reduce
de-correlation noise.
