A capability to quantify the size of bubbles has been developed using time delay spectrometry. This signal processing technique uses swept frequenceis and matched filter detection. It can provide either ranging or frequency response data based upon fundamental or second harmonic signal processing. This system has been tested using bubbles in the 1–50 micron range. The use of this signal processing provides a technique that is both quantitative and capable of uniquely characterizing bubbles and their size distributions.