November 25, 1998 transcript # 261-3
Subject(s): air pressure, ear popping
Title: Chewing Gum

It might not be apparent, but the air around us actually has weight. Really, it has mass, and combined with gravity, it creates weight. Therefore, it exerts a force on all of us. But we can't feel that force; that force is exerted equally from inside and outside our body. But there is a way that you can feel it, and that's when you go up in the atmosphere, as the air pressure decreases. That rapid drop can cause a phenomenon that may make you want to yawn or chew gum. Hi, I'm Dave Thurlow and this is The Weather Notebook.

Now, this ear-popping phenomenon you get with pressure changes in a-- say a plane, for example-- is the body's natural response to protect your eardrums from damage. Now, here's what happens: the airplane takes off, and the cabin pressure drops and so does the air pressure on your outer ear. Since there's no similar compensating change in pressure on the middle ear (inside the head), the eardrum which separates the middle and outer ear-- bulges outward because of the pressure differential and things start to sound muffled. Then, when you descend in the airplane, the opposite happens, the eardrum bulges inward and things begin to sound unmuffled. Now, in both cases, it's the deformation of the eardrum that causes pain and the discomfort as well as muffled sounds, because the eardrum does not vibrate as efficiently.

So why does chewing gum help? Well, when you chew or swallow or yawn, this allows the pressure in your middle ear inside your head to equilibrate with the outside pressure. When this happens, the eardrum pops back to its normal shape. So, what you hear as ear popping is actually the vibrations from the rapid change in the shape of your eardrum. Something to contemplate the next time you fly, or the next time you drive up a mountain - say, like Mount Washington which is home of the Mount Washington Observatory, who produces our show. Our show was written today by Jeanne Twehous. Thanks to Subaru and to the National Science Foundation.