Note: in the serial output, i didn't have the ping sensor hooked up but it normally does work, read correctly, and trigger the correct file.
Here's a bit of an update:
I removed the ping sensor code and switched all the if/ else if statements to 10 == 10, 20 == 20, ect so that the first file always triggers and there's no code discrepancies. First file plays perfectly. Somehow, the few lines of ping sensor code is causing the files not to play. Anyone have any ideas?