My only comment to those 'learned' university professors is that I work in a store where fork lifts operate all night long (and yes, I drove them for 7 years). The Gas FLT engine noise is so loud, you can NOT hear the white-noise sound, where you can the beep. You can hear the engine, but not know if it is traveling or just elevating a load. With the electric FLTs, the white noise 'echos' around the aisles, you can not tell from which aisle the sound is coming from. With the Beep, you can tell from which side of the isle you are in the noise is coming from. White noise may be great on a building site, but it is CRAP inside a store!,(reply>), just listened to some examples, one being a forklikft as well, and its engine is quite a bit louder. even in the open.<br>I'll accept that theoretically the white noise is better, but people should still use some more common sense than "this is what's perscribed, so let's just use that". Do some field tests in their actual use environments before replace all your alarms.