Sound velocity and attenuation measurements have been made in bubble clouds comprised of water and air. It has been known for some time that the sound velocity in a bubbly liquid is less than that of either the gas or liquid phase (e.g., 70 m/s at 2% void fraction for air bubbles in water). Standing-wave and time-of-flight methods in cylindrical tubes were used. A standing-wave technique patterned after Silberman [J. Acoust. Soc. Am. 29, 925 (1957)] was used to measure sound velocity at low void fractions (<2%). In this work, more attention was given to the problem of obtaining a more uniform bubble size distribution which was not present in Silberman’s experiment. To achieve this, hypodermic needles were used to produce a reasonably nondispersive bubble size distribution within the cloud. Also, time-of-flight measurements were made at pulse frequencies well below the bubble resonance to observe the dependence of high void fraction (≳10%) on sound velocity and attenuation. [Work supported by ONR.]