Hi folks!
If Ciao has searched the forum, she has most certainly uncovered all the arguments against riding with earphones. We're big girls
and can make up our own minds about this, so maybe we can stick to trying to answer her question? This discussion is so far low-key, but does tend to get a little volatile. Thanks 
On the two-way radio thing - some rock climbers doing long routes use small two-way radios that they tape to one strap of a shoulder harness or backpack, voice-activated, so you can mumble down into your shoulder and your partner will hopefully hear you. Might work on the road too.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett