Some people like I, the pilot with every thing damn thing wrong with him, have probs with clearing the ears during decents. In some people the eustatian tube does not work as well as it should do. ( as with me ) We have to start swallowing very early in the decent or we will experience very sever pain. It's also a pain in the As* too as swallowing all the time from 35,000 ft rather drys the mouth out.