  The bubble nucleation in superheated liquid can be controlled by adjusting
the ambient pressure and temperature. At higher pressure the threshold energy
for bubble nucleation increases and we have observed that the amplitude of the
acoustic emission during vaporisation of superheated droplet decreases with
increase in pressure at any given temperature. Other acoustic parameters such
as the primary harmonic frequency and the decay time constant of the acoustic
signal also decrease with increase in pressure. It is independent of the type
of superheated liquid. The decrease in signal amplitude limits the detection of
bubble nucleation at higher pressure. This effect is explained by the
microbubble growth dynamics in superheated liquid.
