I get a lot of helmet vibration (the roaring sound) when riding due to the turbulent blowoff from my windshield. I use earplugs to minimize the noise. I am 6' 4" and wear a full coverage Arai helmet, so my head projects into the turbulent wind stream.
At 70, I also had a sudden onset sensoaural (sp?) hearing loss two years ago, and have tried digital hearing aids to try to improve what hearing I have left. These hearing aids have not been very successful at all. My best hearing situation is using a full headset w a TV so that all outside sound is blocked. My hearing loss is -30 db in my good ear, and -50 db in my bad ear and tinnitus in my bad ear. Not very good at all.
We have to travel using the "pound-on-the-back" intercom. Not very effective.
I assume that any ordinary earphone inserts into our helmets to improve communications would be impractical. Is there anyone that disagrees? I wish an intercom could be used.