m/s-1
m
kg/m-3
Nm-2
hz

Formula

fc= [ sqrt(3)c2/pi*d ] * [ sqrt(ρ/Y) ] Where,

fc = Coincidence Frequency [Hz]
c = Speed of sound in air [ms-1]
d = Thickness of panel [m]
ρ = Density of panel [kgm-3]
Y = Young\'s modulus of panel [Nm-2]