The audio begins with a soft, distant rumble growing steadily louder, indicating the approach of a massive object. Gradually, the sound morphs into a powerful, all-encompassing hum, the unmistakable roar of a gargantuan engine. The noise is resonant and rhythmic, reminiscent of a powerful locomotive's heartbeat. The hum grows until it seems to surround you entirely, creating a sense of the train rushing past at high speed. Just as quickly as it grew, the sound starts to fade, the powerful hum diminishing back into a distant rumble, leaving behind a sense of awe at the sheer power and magnitude of the passing train.