Building Acoustics | Absorption from Lightweight Wall is most accurate for single leaf walls.
The formula below provides an approximation for the random-incidence sound absorption coefficient `alpha_(rand)` of a single, flexible, homogenous, isotropic, nonporous partition:
`alpha^("rand")\approx 10^(-"TL"_("rand")/10)+(2\pi\sqrt(12)\rho_0c_0^3\sigma_("rad"))/(\rho_Mh^2c_L\omega^2)`
where:
`"TL"_("rand")` is the random-incidence sound transmission loss of panel (measured or predicted)
`\omega` is the angular frequency, `2\pif`
`f` is the frequency, `Hz`
`\sigma_("rad")` is the radiation efficiency of free bending waves
`\rho_M` is the density of the plater material, `"kg"/m^3`
`h` is the plate thickness, `m`
`c_L` is the speed of sound in the plate material, `m/s`
References:
Vér, I.L. & Beranek, L. L. (2006) Noise and Vibration Control Engineering: Principles and Applications, Second Edition, equation 8.9