It was shown that intense ultrasound gave rise to an experimentally observed non-locality in the acousto-dislocation interaction. This was seen as an hysteretic dependence of the damping coefficient of an acoustic wave upon the wave amplitude; including a decrease in damping.

Acoustic Hysteresis Phenomena due to Dislocation Non-Linearity in Crystals. G.N.Burlak, I.V.Ostrovskii: Technical Physics Letters, 1997, 23[9], 725-6