I used to work at a grocery store, and I started up working in the meat department.  In case you don't know, the prep-room is virtually a bit freezer, with big fans blowing cool air constantly, and packaging machines running.

Now, if you were going to issue someone an order or ask them a favor, you would raise your voice a bit, wouldn't you?  You know, to help elevate it above the surrounding din.

I don't know why this was such a hard concept for my co-workers.  I guess not going to college will do that to ya.