A loud speaker at a rock concert generates 102 W/m2 at 20m with a frequency of 1
kHz. Assume that the speaker spreads its intensity uniformly in all direction.
(a) What is the sound level ( = ?) at 20 m?
(b) What is the total acoustic power output of the speaker?
(c) At what distance will intensity level be at the pain threshold of 120 dB?
(d) Determine the sound intensity at a distance of 30 m?