Particle velocity level Particle velocity

sound velocity level (svl) or acoustic velocity level or particle velocity level logarithmic measure of effective particle velocity of sound relative reference value.

sound velocity level, denoted lv , measured in db, defined by

l

v


=
ln


(


v

v

0




)


 

n
p

=
2

log

10




(


v

v

0




)


 

b

=
20

log

10




(


v

v

0




)


 

d
b

,


{\displaystyle l_{v}=\ln \!\left({\frac {v}{v_{0}}}\right)\!~\mathrm {np} =2\log _{10}\!\left({\frac {v}{v_{0}}}\right)\!~\mathrm {b} =20\log _{10}\!\left({\frac {v}{v_{0}}}\right)\!~\mathrm {db} ,}

where

v root mean square particle velocity;
v0 reference particle velocity;
1 np = 1 neper;
1 b = 1/2 ln 10 bel;
1 db = 1/20 ln 10 decibel.

the commonly used reference particle velocity in air is

v

0


=
5
×

10

−
8


 

m

/

s

.


{\displaystyle v_{0}=5\times 10^{-8}~\mathrm {m/s} .}

the proper notations sound velocity level using reference lv/(5 × 10 m/s) or lv (re 5 × 10 m/s), notations db svl, db(svl), dbsvl, or dbsvl common, if not accepted si.