I'm now wondering if I've ever heard this sound.<br><br>Maybe I have but just assumed it was a hydraulic brake or something.,(reply>), @Harold Balzac I sure as hell trust academic paper more than a random youtube comment.,(reply>), @Jamie Phipps Just because it's better on paper doesn't mean it works out in the real world. Beeping has been the staple of heavy vehicle reversal for so long it's ingrained in almost everyone's head.,(reply>), Hydraulic brake probably wouldn't make a sound like that. Pneumatic breaks would.,(reply>), Sounds like air bleeding off of a pressurized system.  Not an alarm to passers by.<br>What are the accident statistics?,(reply>), @Matt Nowak how deluded do you have to be to see something that's been proven by rigourous academic research but then just say the exact opposite? Mind blowing.