Re: headphones in a helmet
HJC has the helmet intercom that attaches to the helmet....
the earphone pieces can be shoved in the space in the helmet where your ears go. you can plug in a cellphone, cd player, mp3 player, etc into the intercom as well.
if you have an HJC helmet, the space for the ears are large enough to accomodate the HJC earpieces without squishing your ears. I had the HJC intercom (aka Chatterbox) in my Arai and my ears were always sore after riding. I got an HJC helmet and switched the intercom unit - no problems with sore ears using that configuration