ear pop

Reader's Digest 4月号の記事 '8 Things You Should Never Do on an Airplane' からの抜粋です。
FALL ASLEEP BEFORE TAKE OFF
If you do, it will be harder for you to equalize the pressure in you ears (which you'll do more quickly if you chew gum or yawn). If you're prone to flight-induced haeadaches, hold off on your snooze until your ears pop.
"ears pop" は飛行機に乗っていて、特に上空で経験する耳が痛くなる現象の事ですね。辞書の説明を見ます。
・Oxford English Dictionary: (of a person's ears) make a small popping sound within the head as pressure is equalized, typically because of a change of altitude.: I remember my ears popping as we rode the elevators to the top.
・Cambridge English Dictionary: If your ears pop, you experience a strange noise and feeling in your ears as a result of a sudden change in air pressure: My ears always pop as the plane comes in to land.
私の場合は耳が痛くなるだけで音や雑音はきこえませんが、英米人の耳は何か雑音が聞こえるのでしょうか？　もちろん痛みを止めるために空気抜けをする時には音がしますね。