Abstract: A method and apparatus for continuously measuring and indicating the variations of the intensity of an electric signal, such as a signal to be recorded on a tape recorder, which provides measuring to take place at successive measuring periods in such a manner that a measured result is yielded representing the maximum value of the signal intensity. The signal intensity is measured during consecutive measuring periods and registered. The indicator has the ability to maintain the read-out of a maximum value, read during a measuring period, during a following hold period, whereby the measuring periods provided have a duration being an order of size less than the time of reaction of the human eye. The system stores the maximum intensity values being detected during each of a series of consecutive measuring periods, and provides hold periods having substantially longer durations by being an order of size longer than the time of reaction of the human eye.

Abstract: A sound transmission and reproduction system including at the transmitter side means for producing a non-audible control signal indicative of a predetermined character of the transmitted sound, preferably the intensity of the sound as actually transmitted, whereby the transmitted sound may be artificially attenuated and amplified, respectively, in respective passages of high and low intensity so as to be transmittable within a restricted dynamic range. At the receiver side the control signal is detected and used for controlling the amplifier as an automatic volume control so as to effect extra amplification of the attentuated passages and attenuation of the artificially amplified passages so as to enable the reproduction to take place with the full dynamic range of the original sound.