Rapporteur report: Mechanisms and interactions.

The first two talks of this session described the basic characteristics of the interaction of ultrasound with matter, the first (by V.F. Humphrey) concentrating on the physical interactions, with the second (by W.D. O'Brien, Jr.) focusing on the biophysical effects and mechanisms. The regimes covered by the first and second talks were of primarily high-frequency (O(MHz)) ultrasound in liquids and tissue, respectively. In contrast, the third and final talk of the session (by M. Alves-Pereira) discussed observations made by her group of the vibroacoustic effects of low-frequency noise and infrasound, propagating through air, on humans and animals.