my general rule is that they can, so long as it is not to loud. If I walk up behind them and say something to them, they better hear me. If they don't the ipod guys back in the truck. While running equipment on an install the operator wears a set of hearing protection with a built in 2way radio. The ones we have are nice, they have a mp3 jack. If someone begins to talk over the 2way the mp3 jack is automaticaly muted. I couldn't work all day in my skid or mini ex without listening to the radio.
Why do people not respect us as they do other tradesmen? Because every Tom, Dick, and Harry doesn't think he can be a plumber or electrician!