The automatic measurement of reverberation time includes the making of special recording which is characteristic of the studio or other room tested; equipment subsequently selects the required signals from the recording, converts them to digital form and punches a paper tape describing relevant characteristics of the signals. Reverberation times may then be calculated using suitable computer programmes. The advantages over conventional methods of measurements include a reduction in the number of man-hours required, more objective results and the storage of studio sound-decay data on an inexpensive medium.