A technique known as the "valsalva maneuver" is sometimes used to allevaite this condition, but it's not always successful. In a nut shell, one takes a deep breath and closes one's mouth, then pinches the nose while attempting to "blow."
SLF here, a trick that works for me when one ear is blocked (usually the case), is to pinch the nose, and the unblocked ear with a finger and then ''blow''.