If both pilots have a headset, the interphone is used. If one doesn't have a headset, then no interphone. In that case I just fly with my right earcup off. Not at all uncomfortable with the DC. Even when both pilots have a headset I tend to fly the approach with one earcup pulled back because I like to hear the engines a bit. That and I know it's time to flare when I hear the FO suck in his/her breath, which is vital because I can't figure out how to land this POS uberguppy.