If it is really bad during decent which my daughter experiences....a friend told us of a trick that works every time. You ask a flight attendant for two stryoform cups (coffee), have her/him put a bit of steaming hot water into the bottom..just a bit, then stuff paper towels on top so it doesn't leak out then hold the cups over the ears. Instant relief to the pain/pressure.
We've been on multiple flights and we've only had one flight attendant that wasn't willing to provide us with it...(and she was not a very nice person).