  This study investigates the emission of light and sound from cavitation
caused by intense pressure pulses in water. Based on time-resolved measurements
of (a) pressure waveform at the focus, (b) light scattering upon cavitation,
(c) acoustic emission, and (d) photoemission (sonoluminescence) it is shown
that emissions occur upon the creation or expansion as well as the collapse of
the cavity. These results suggest that the thermodynamic irreversibility,
resulting from non-equilibrium phase transition and changes in surface entropy,
is a basis for photo and acoustic emissions during cavitation.
