If you search this is a very common issue, first try tightening the screw that holds the ear piece on, there is a black screw driver thing in the box with the lens cloth. If that does no good swap the left and right if the fault stays with the right side contact oculus support for replacement if under warranty, they will apparently ask you to do some testing etc. and then authorise the replacement. Mine takes turns with the sides cutting out but it is always a lose screw or on a couple of occasions a quick clean of the contacts, but my Rift is very heavily used, I have recently got into the habit of tightening the screws with my finger occasionally and I have had no more issues. Good luck
