The intensity level of sound 18 m from a jet airliner is 120 dB.At what distance from the airplane will the sound intensity level be a tolerable 100 dB? (Assume spherical spreading of sound. )

Question

Quizplus · Accepted Answer

Use the inverse square law to solve for the new distance.
I1/I2 = (r2/r1)^2
I1 = 120 dB, I2 = 100 dB
r1 = 18 m
r2 = ? 
Substitute the values and solve for r2.
100/120 = (r2/18)^2
r2 = 232 m (approx)

The Intensity Level of Sound 18 M from a Jet