This had been working since I got it a month ago, but I have been in the process of gluing the windows back in and adding figures. I finally finished the 4th car and hooked it up. It ran around my loop once, opened and closed the doors and then the sounds started going strange and distorted. I have reset the Subway and even tried it conventionally and it has the same issue. The sounds will crackle for a bit and then the conductor will start announcing stations back to back. The speaker sounds like it works fine so I'm not sure what the deal is here.
It doesn't start doing this until I address the ID and power it on so it's somehow replacing the engine sounds with the distortion. The video below shows the sequence from addressing the ID, powering it on, and then the conductor goes wacky.