A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 54 dB by an observer 10 kilometer away.
(a) Compute the average power generated by the horn?
_______________W
(b) Find what intensity level of the horn's sound is observed by someone waiting at an intersection 46 meter from the train? Treat the horn as a point source and ignore any absorption of sound by the air.
_______________dB