  We describe a semiconductor multilayer structure based in acoustic phonon
cavities and achievable with MBE technology, designed to display acoustic
phonon Bloch oscillations. We show that forward and backscattering Raman
spectra give a direct measure of the created phononic Wannier-Stark ladder. We
also discuss the use of femtosecond laser impulsions for the generation and
direct probe of the induced phonon Bloch oscillations. We propose a gedanken
experiment based in an integrated phonon source-structure-detector device, and
we present calculations of pump and probe time dependent optical reflectivity
that evidence temporal beatings in agreement with the Wannier-Stark ladder
energy splitting.
