Sounds like air brakes being applied... no worries, the truck is braking.<br>Beep, beep, beep, something is backing up.,(reply>), what makes you think the white noise isn't pulsing?,(reply>), @Zoravar .K No it doesn't.,(reply>), @Zoravar .K You're bending over backwards to come up with justifications for the obviously wrong answer.,(reply>), I agree Moore. <br>Here in the Midlands it's rare to have to pick out reversing noises from overtly loud backgrounds (unlike cities), so the rasping's main purpose is kind of moot.<br><br>People <b>expect</b> beeping &amp; immediately think "something's reversing", thus it's odd that they introduced hissing without any real attempt at a public information campaign.,(reply>), I've mistaken it for air break noises in the past, did look to see what was going on. It is easier to judge if this sound is moving towards you or not but that won't come across from a video very well.