Due to a point isotropic sound source, the sound level at a point is observed as 40 dB. The density of air is ρ = 1511kg/m3 and velocity of sound in air is 330 m/s. (The threshold intensity is 10−12Wm2)
The pressure amplitude at the observation point is x(10−3)N/m2. Then x = _____
3
In the propagation of sound waves, let pressure amplitude be Δp0 and displacement amplitude be A.
Δp0 = BAK where symbols have their usual meanings
From SL = 10log II0
40 = 10logI10−12 ⇒ I = 10−8W/m2
From I = Δp202 ρv
Δp0 = √I×2ρv = √10−8×2×1511×330N/m2