科學一刻 耳鳴

　　The Eustachian tube opens to equalize the pressure between our ears and the airplane cabin.

　　Popping Off

　　When traveling by plane what makes our ears pop, and what is it exactly that pops?

　　Most of us are familiar with this phenomenon of travel: ear-popping usually happens during takeoffs and landings.

　　Our ears pop because of the change in air pressure as the plane ascends or descends. At higher altitudes air pressure is lower, even though the plane is pressurized. Our ears are sealed off inside our heads, so as the plane ascends or descends the pressure outside and inside our ears is different. This difference in pressure can distort our ear drums and be painful.

　　Under Pressure

　　What needs to be done here is to equalize the pressure between our ears and the airplane cabin. Nature has provided the means for this with a tube that runs from the middle ear to the nasopharynx—the open area behind our noses. It’s called the Eustachian tube. Normally the Eustachian tube is closed, so in order to equalize the pressure we need to open it. Seasoned travelers know that you can avoid the discomfort by swallowing or chewing gum when you feel the pressure change. The mechanical action when we chew gum or swallow opens the Eustachian tube, and allows the pressure to be equalized. The opening of the Eustachian tube is associated with the “pop” we hear.

　　Incidentally, babies often cry on takeoff and landing because they don’t know to chew or swallow. Having them suck on something can open their Eustachian tubes and alleviate the

　　pain on their ears…and the other passengers’.