The D60LFR is an articulated low-floor bus built by New Flyer and used by transit agencies across North America, so its air brake release is a familiar sound at city stops and depots. Clips like this are usually recorded from real buses rather than created in a studio, which is why editors reach for them when a generic brake hiss sounds too clean or artificial. Its specificity is the appeal: listeners who ride these buses recognise the exact tone instantly.