I live in the UK and I've never heard this noise. I've heard "Warning. This vehicle is reversing. Warning. This vehicle is reversing." though. Maybe I just don't get out enough?<br><br>EDIT: Ok I found another video of it and realized I have heard this sound, I just assumed it was compressed air escaping or something (obviously I have no idea how construction vehicles work!).,(reply>), @soupalex 1. Nope, not required. New vehicles are required to have backup cameras, but that's all.<br><br>2. The fact it'd take three pulses instead of one is exactly the problem<br><br>3. Usually they are common for about an hour out of every week.<br><br>4. See 2.,(reply>), @Nathan Lang 1. in situations where a large vehicle is required to reverse around untrained persons, there is generally a requirement for a banksman to be present (in the uk, idk about the usa)<br>2. you could be forgiven for mistaking one or two pulses were an air brake activation. more than that and you'd likely realise that air brakes don't actually sound like this alarm—abrupt attack and release, perfectly regular repeating pattern<br>3. it's not that the sound "travels further", it's that it is far more likely to be heard over other noises (allowing it to be operated safely at lower volumes… most noise complaints in built-up areas are historically due to "beep beep" reversing alarms) and is much easier to correctly identify the direction of<br>4. are you really telling me that, if you heard a loud "pssh! pssh!" noise, at regular intervals, and getting louder… rather than looking in the direction of the noise, you would just think "welp, must be an intermittent air brake being fired repeatedly and getting closer to me… no point in looking!"?,(reply>), @soupalex it also needs to be noticeable for untrained people. What about a truck backing up in a parking lot? Actually, the most common place I hear a backup alarm is from garbage trucks when yhey occasionally overshoot a bin. It's a very audible, very well known, 1kHz beep.<br><br>Another noise average people hear is air brakes. This white noise sounds exactly like that, and now people will think that it's the sounds of a vehicle using its brakes, not reversing.<br><br>Idiotic and dangerous. I don't care how far white noise theoretically travels, I care what it actually means to the people heating it.,(reply>), @soupalex :  Heh heh....not the same thing, though.,(reply>), @Captain Quirk "vaccines are better at treating viral infections than homeopathy? Says who!? Some egghead, no doubt"