particle velocity level

3.23  particle velocity level. Ten times the logarithm to the base ten of the ratio of the time-mean-square particle velocity of a given sound or vibration to the square of a specified reference value for particle velocity. Unit, decibel (dB); symbol, L_v.

Annotation              Clause A.1 of ANSI/ASA S1.8-1989 (R 2011) notes that a reference value for particle velocity of 10 nm/s was used in ANSI S1.8-1969, in contrast with 1 nm/s given in ISO 1683:2008. It is important to state the reference value for particle velocity level when describing velocity levels.