Here is a fascinating paper bearing on Newtonian and Relativistic limits, equivalent Photon and Phonon Physics, and a burning Relativistic QM controversy over Super-Luminal Tunneling Velocity-

On virtual phonons, photons, and electrons
Gunter Nimtz
Physikalisches Institut, Universtat zu Koln

Based on previous literature study and experimental phonon work, I think the faster-than-c observations are a subtle combination of relativistic illusion and poorly understood tunneling dynamics, best detailed in related topics.

This paper also involves Virtual Particles; an interesting comparison to Quasiparticles. All Particles are increasing seen as extended (non-local) Field Excitations, and its not proven any particle is truly fundamental.