As people sing in church, the sound level everywhere inside is 107 dB. No sound is transmitted through the massive walls, but all the windows and doors are open on a summer morning. Their total area is 23.0 m2. (a) How much sound energy is radiated in 18.0 min? J (b) Suppose the ground is a good reflector and sound radiates uniformly in all horizontal and upward directions. Find the sound level 1.8 km away. dB