Assume that the displacement (s) of air is proportional to the pressure difference ΔP created by a sound wave. Displacement (S) further depends on the speed of sound v, density of air ρ and the frequency  f.If ΔP~10Pa, v~300m/s,ρ~1kg/m3 and f~1000Hz then s will be of  the order of ( take multiplicative constant to be 1)