A new method has been used for the study of noise arising from the collapse of cavitation bubbles. Isolated vapor bubbles were formed in de‐aerated water undergoing vertical vibrations of about 1/30 sec period, whose amplitude was sufficiently large for the water to be in tension for part of the cycle. The bubbles were initiated from minute gas nuclei released by electrolysis at a certain instant each cycle; consequently, a long succession of identical bubbles was produced, each of which repeated the same sequence of growth, collapse, and several rebounds, and then disappeared before its successor became due. The noise pulse could conveniently be examined by displaying a hydrophone signal on an oscilloscope adjusted for fast single‐sweep operation but triggered repetitively (by the signal from a second hydrophone placed nearer the noise source) at the frequency of bubble formation. The pulse was found typically to have a duration of about 10 μsec, and under certain conditions to undergo steepening such as to develop a shock front of duration considerably less than 1 μsec.