Find the average power and intensity level of a horn's sound, and difference in decibel levels of a sound source.
a. A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 50 dB by an observer 10km away. (i) What is the average power generated by the horn? (ii) What intensity level of horn's sound is observed by someone waiting at an intersection 50m from the train?
b. Show that the difference in decibel levels β1 and β2 of a sound source is related to the ratio of its distances r1 and r2from the receiver by the formula.