Abstract
Acoustic emission from a single bubble is observed using a needle-type hydrophone and compared with Mie-scattering data. The acoustic emission is composed of two signals, i.e., pulses occuring at the moment of collapse and background emission ΔV. The average of ΔV and the maximum radius can be grouped to two types of collpase. The average power of ΔV is proportinal to or increase more rapidly than R3max. It is suggested that the background emision is associated with multipolar source of acoustic waves in which vortices surrounding the bubble play an important role.
