Results of three different approaches to bubble measurement, multifrequency backscatter, pulse propagation, and complex dispersion measurements with an acoustic resonator, are compared. The multifrequency backscatter sonar has the advantage of being a remote sensor and provides high resolution up to the sea surface. However, the limited number of available frequencies and cumulative effects of attenuation due to bubble scatter complicate the inversion. The pulse propagation sonar is an in situ measurement depending on detection of travel time and attenuation for a pulse traveling between two transducers. It has the merit of providing a direct sound-speed and attenuation measurement and may conveniently be operated at quite low frequencies. A resonator that allows simultaneous measurement of sound speed and attenuation spanning the resonant bubble frequency range of interest has been developed. Measurements in three open ocean deployments provide a basis for systematic comparisons between the different bubble detection and different inversion techniques.