Wave propagation of low-void-fraction, two-phase bubbly flow is analyzed from the compressibility of a bubble and an assumption of homogeneity for steam bubbles. The phase velocity and attenuation calculated from the model are strongly dependent on frequency. The equilibrium sound velocity is derived for the limiting case as frequency approaches zero. The second resonance of a vapor bubble is also discussed. In addition, the void fraction, bubble size, and noncondens-able gas effects are also analyzed in the model. The relationship between sound velocity and interfacial area density is derived, and a new method to measure interfacial area is proposed.