Acoustic intensities up to 1400 W/cm2have been generated at the focus of a ceramic bowl. The rf voltage applied to the transducer has been rectified and filtered and the signals produced from cavitation events have been examined. A directional hydrophone simultaneously monitoring the focal point aided interpretation of the signals detected by the driven bowl. Low‐amplitude low‐frequency signals appeared on the driven bowl synchronously with the onset of first subharmonic emission in the water at an intensity of 13 W/cm2. The subharmonic increased rapidly with increasing sound intensity and then leveled off. Just before this occurred, the scattering properties of the focal region increased markedly and a cyclic signal, interpreted as indicating the production of clouds of microbubbles when surface oscillations set in on the cavitation bubbles, was detected on the filter circuit. Strongly radiating single cavitation events lasting for the order of milliseconds were also detected. The amplitude, duration, and rate of occurrence of these events were all one to two orders of magnitude greater in tap than in degassed water.