Speakers quit working after something fell on car

Okay, I cannot fathom why this affected my speakers, but I was driving in a construction area when I felt and heard a big bump on top of the car. It was as if something fell on top of the roof. It was loud and it made me duck my head.

I had been listening to XM radio before the noise, but after I recovered from the scare, I noticed that the radio had gone off. I tried turning it up and the interface showed that sound was there, but there was nothing coming from the speakers.

On inspection of the car, I found no evidence of damage.

Weird