A boy is sitting in the passenger side of a van with the window rolled down. As another car drives by he can hear really loud music coming from the radio inside of the other car, so he rolls up all of the van's windows. When he does, he notices that he can still hear the music from the other car, even though it does not sound as loud as it did before. a. How is it possible that the boy can hear music coming from a radio outside of his van, even if he is within a completely enclosed space surrounded by solid material (the van)?

When the car gets 100 feet away from the van, the boy can barely hear the music. But then, when the van and car enter a tunnel together, the music sounds much louder, even though the car is still 100 feet away, the windows are still closed, and the driver in the car did not adjust the volume of the radio.

b. Explain why being inside the tunnel makes the music sound louder to the boy in the van than when the car and van were both outside of it?