### Strutt Help

Lw from Vibrating Surface ^{1/1, 1/3}
**Strutt|Vibration|Lw from Vibrating Surface** calculates the sound power level of a vibrating surface.

Strutt implements the formula as:

`L_w = 10log((S rho_0 c_0 sigma v^2)/W_(ref))`

where:

`L_w` is the radiated sound power level of the vibrating surface (dB re 1 pW)

`v` is the vibration velocity (m/s) of the vibration surface

`S` is the surface area (m²) of the vibrating surface

`rho_0` is the density of air (kg/m³), by default 1.21 kg/m³

`c_0` is the speed of sound in air (m/s), by default 343 m/s

`sigma` is the radiation efficiency of the vibrating surface (usually 1.0 above the critical frequency of the surface)

`W_(ref)` is the reference sound power level of `1*10^-12` (W)

Reference: Bies and Hansen *Engineering Noise Control*, Third Edition Section 6.7

Comments or suggestions to
strutt@arup.com