Due to a point isotropic sonic source, loudness at a point is L = 60 dB. If density of air is ρ=(1511)kg/m3 and velocity of sound in air is v = 330 m/s, the pressure oscillation amplitude at the point of observation is [I0=10−12 W/m2]
60 dB=10 dB log II0
⇒I=(106×10−12) W/m2=10−6 W/m2
[I0=10−12 W/m2]
I=(ΔPm)22pv
Where ρ=1511 kg/m3,v=330 m/s
∴(ΔPm)2=2ρvl=2×1511×330×10−6
⇒ΔPm=0.03 N/m2