Elephants communicate via infrasound, at frequencies as low as 14 Hz that can travel up to 10 km. The intensity of these sounds can reach 103 dB, measured a distance of 5.0 m from the source. Determine the intensity level of the infrasound 10 km from the source, assuming the sound energy radiates uniformly in all directions.

Answer 1

I2/I1 = R1^2/R2^2 = 5^2/(10^4)^2
= 25 * 10^-8
10 log (25*10^-8) = 10 [-8 + 1.4]
= - 66 dB

103 - 66 = 37 dB
still pretty loud