The Volume Unit table was established by the American Acoustical Society in 1942 (ANSI C16.5-1942) and is mainly used in the telephone and broadcasting industries.
Dynamic characteristics of the VU table: The dynamic characteristics of the VU table can be described by rise time, recovery time, and damping characteristics. The rise time is defined as 0dB (that is, the level value defined at 0VU, China is +4dBu), and when the 1kHz sine wave is suddenly added to the VU meter, the time required for the pointer to rise from 0 to 99% of the scale is specified. It is 0.3 seconds. The definition of recovery time refers to the time required to reduce from 100% to 1%, which is also specified as 0.3 seconds. The damping characteristic is defined as that when the sine wave of 0 dB and 1 kHz is suddenly applied to the meter and the pointer reaches 0 dB, the overshoot should not exceed 1 to 1.5% of the stable value, and the number of oscillations should not exceed one.