Reverberation measurements, made in rooms where the absorption is nonuniformly distributed, usually vary widely from predictions based on the currently employed formulas. Through extensive tests made in a large number of rooms, where distribution of sound absorption varies widely in uniformity, an empirically derived equation is submitted. Photographs of graphic recorder decay curves, showing contrasts in predicted slopes, seem to confirm the validity of the formula. The recorder curves are from field tests. The data submitted are a small portion of an accumulation of measurements, covering several years, in rooms of widely varying volumes, widely varying boundary ratios, and marked dissimilarity in amounts of absorption and ratios of absorption distribution.