The mass of the needle causes a relatively slow response, which in effect integrates or smooths the signal, with a rise time of 300 ms. The original VU meter is a passive electromechanical device, namely a 200 ♚ DC d'Arsonval movement ammeter fed from a full-wave copper-oxide rectifier mounted within the meter case. in recording equipment) and for aesthetics (in playback devices). The Acoustical Society of America then standardized it in 1942 (ANSI C16.5-1942) for use in telephone installation and radio broadcast stations.Ĭonsumer audio equipment often features VU meters, both for utility purposes (e.g. The original design was proposed in the 1940 IRE paper, A New Standard Volume Indicator and Reference Level, written by experts from CBS, NBC, and Bell Telephone Laboratories. Audio signal level measurement device An analog VU meter with peak LEDĪ volume unit ( VU) meter or standard volume indicator ( SVI) is a device displaying a representation of the signal level in audio equipment.