Acoustic spectroscopy was used to monitor the droplet size distribution in a classic three component system of heptane, water, and aerosol-OT (AOT), The size of the reverse microemulsion drops was varied by changing the molar ratio of water to AOT surfactant. The acoustic results for this transparent microemulsion were found to be in close agreement with literature results obtained with small angle neutron scattering and small angle X-ray scattering. The system was investigated well into the turbid region where microemulsion changes to macroemulsion, The droplet size distribution was found to shift to a bimodal form due to this transition.