Hmm, that might be a perfect use of an iPod...

I was looking into a helmet with a hookup of some time available for a headset, in case I want to hook it into a two way radio. An iPod might work as well for this, and I do already have the G4 cube to hook it to...

An example of the speaker system is here: http://www.alfenterprises.com/rf_limited_ch550.htm

The audio jack on that one looks seperate from the microphone, so it should be easy enough.