Public buses in Singapore use an automated doors closing warning to alert passengers to stand clear before the doors shut, part of the standard safety announcements heard throughout the ride. Recordings of the chime and voice prompt have been shared online by commuters and transit enthusiasts, and the clip has spread as a niche sound effect for travel edits. Because the sound is so specific to everyday commuting in Singapore, creators use it to instantly set a location or to add a realistic transport detail that regular passengers immediately recognise.