that just seems like a horrible idea. first off, the beeping is instantly recognizable as something that says "a truck is backing up." The white noise just sounds like air brakes purging or some other random construction noise. also, it may be easier to pinpoint the source of the sound with white noise, but that white noise can easily be washed out by all the other white noise present in your average construction zone. with the beep, at least nothing else on a work site tends to make that sounds other than reversing trucks.