This recording comes from a Class 717 train, a type of modern electric multiple unit whose door chimes and sliding doors are also heard on similar trains across busy commuter networks. Sounds like this are shared on soundboards because they are hard to capture cleanly without station noise, and creators prefer a ready-made clip to recording their own. It remains useful because train travel is a common visual shorthand for commuting, leaving home, and everyday city life, so the sound instantly anchors a scene without drawing attention to itself.