Reverberation measurements, made in rooms where the absorption is nonuniformly distributed, usually vary widely from the predictions based on the usually employed formulas. Through extensive tests made in a large number of rooms, where distribution of sound absorption varies widely in uniformity, an empirically derived formula 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 records taken in the field. The data submitted are a small portion of an accumulation of measurements, covering a period of some five to six years, in rooms of widely varying volumes, widely varying boundary ratios, and marked dissimilarity in amounts of absorption and ratios of absorption distribution. This paper also includes a discussion of the new semicircular California Masonic Memorial Temple 3300-seat auditorium, recently completed in San Francisco, together with experiences with other rooms of difficult shapes. (This is an expansion of a paper, originally planned for the Washington meeting but not delivered.)