An automatic meter for measuring the decay rate in a room is described. The meter is based on a proposal by M. R. Schroeder [J. Acoust. Soc. Am. 37, 409–412 (1965)] utilizing the relationship between the integrated impulse response and the average noise response between two points in a reverberent enclosure. The meter takes voltage samples of the integrated impulse response at two freely chosen points in time. These samples are used to calculate automatically the decay rate in decibels/second for the selected time interval. The decay rate is represented by a gated pulse train in which the total number of pulses is equal to the decay rate in decibels/second. The result may be read on a digital counter or a self-contained analog pulse-count meter. Only a single measurement is required to obtain the decay rate corresponding to an average of many noise-decay records.