I can't recommend anyone use something that will block or muffle other sounds that must be heard. If you are able to, then it just as important to hear the sounds of traffic as it is to see traffic.

However for a time, when I was riding with my son a lot, we used the Zello app on a smart phone along with a blue tooth handset that allowed for two way conversation. And the speaker was loud enough to be easily heard by every one around you whether you wanted them to hear or not. But pretty much any bluetooth headset, microphone or earphone you can pair to your phone would work through the Zello app.

And it only requires you to be within cell service. So you don't even have to be near each other. Hanging the hand set on my jersey or bars was easier than fishing the phone out of my pocket and taking out of the zipper bag that I kept it in to keep sweat off of it.

The app essentially just makes your phone work like a walkie talkie. But since you can use bluetooth devices with your phone, you don't have to have direct access to your phone while riding. So you could get a microphone and a earpiece that sits behind your ear and still allows you to hear other things to use with the Zello App.