The coupled phase approach is extended to model sound propagation in an emulsion of two compressible, thermoviscous liquids. This provides an alternative to scattering theory for modeling sound propagation in emulsions in the low-acoustic radius regime. Predictions of the new theory are compared with predictions of multiple-scattering theory and experimental results for ultrasonic velocity and attenuation in an emulsion. For the particular set of experimental data used here, the coupled phase theory gives predictions close to the scattering theory predictions, and a better prediction of the dependence of the attenuation on volume fraction. A similar difference between the two theoretical approaches has been found in earlier work on coupled phase models for sound propagation in suspensions.