I have no idea how they work, but for me they significantly reduce ear pain. I don't experience ear pain on all flights, but when I do I am so glad I have these things. You need to insert them about 30 minutes before landing. The directions say to dispose of them after using twice; not sure why--I keep mine longer and they continue to work. Yes, they also reduce noise--when I have them in my ears I cannot hear/understand anyone around me.

For the small price they cost, if you ever experience ear pain when landing, definitely worth a try.