Stokes's Law of Sound Attenuation


Stokes’s law of sound attenuation is a formula for the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid’s viscosity. It states that the amplitude of a plane wave decreases exponentially with distance traveled, at a rate α given by the formula shown here.

The law and its derivation were published in 1845 by physicist G. G. Stokes, who also developed the well-known Stokes’s law for the friction force in fluid motion.

Related formulas


αattenuation rate (1/m)
ηdynamic viscosity coefficient (pascal*s)
ωsound's angular frequency (1/s)
ρfluid density (kg/m3)
Vspeed of sound in the medium (m/s)