He wasn't in his apartment. He was in the carriage from the recording.
The door at the end of the car creaked open. Something tall, draped in a conductor’s uniform that hung off a frame of rusted rebar and wire, stepped into the light. It didn't have a face—just a speaker grill where a mouth should be. Train Molester.m4a - Google Drive
Elias paused the audio. He was sitting in his apartment, but he suddenly felt the distinct vibration of a train beneath his floorboards. He lived nowhere near the tracks. He looked at the waveform on his screen. The peaks weren't jagged like normal noise; they were rounded, pulsing, like a heartbeat. He wasn't in his apartment