Answer 6—ANSI specification C16.5-1942 (IEC 60268-17), which is titled “Volume Measurements of Electrical Speech and Program waves,” describes the standard audio VU meter. It was jointly developed by Bell Labs, CBS, and NBC, and first put into use in May of 1939.

0 VU is defined to be a level of 4 dBu for an applied sine wave. The VU meter has relatively slow response. It is driven from a full-wave averaging circuit defined to reach 99% full-scale deflection in 300 ms and overshoot not less than 1% and not more than 1.5%. Because a VU meter is optimized for perceived loudness, it is not a good indicator of peak performance.

Contributor: David Tweed

Published February 2004