Chewing Gum and Air Pressure
Name: Kristine J.
Date: Monday, September 30, 2002
One of my students asked how and why chewing gum during a
flight makes your ears pop. I didn't have the answer, but told him I
would try to find out. If you have any information for me, I would
greatly appreciate it. Thank you, Kristine J.
Chewing gum during a flight does not make one's ears pop. Rather, it is the
swallowing that equalizes the throat/inner ear air pressure via the ear's
Eustachian canal that makes the sound one hears. Swallowing repeatedly as
the plane is pressurized repeatedly opens the ear-to-throat connection to
ease the pressure difference on either side of the eardrum. The suggestion
that one chew gum is simply a way to encourage the swallowing action.
The popping during an air flight isn't due to the chewing gum, but is due to
any swallowing action while chewing. The air pressure in an aircraft, in
flight, is about 50% of sea-level pressure. The popping is just the
equalizing of air pressure between the air around the passenger and the
pressure in the passenger's inner ears. When a person swallows, the tubes
from the back of the mouth to the ears open, hence the equalizing of the two
pressures and much relief to the air passenger. Now you know why they hand
out lollies on board, just before descending.
The pop you hear is the air entering or escaping from the inner ear when the
tube connecting your throat with the inner ear opens. You only hear the
popping when there is an unequal pressure on the inside and outside... as in
when you are climbing in the atmosphere to where the pressure around you is
less or descending to where the pressure is greater.
The tube is normally closed, but opens when you yawn, sneeze, or swallow.
Chewing gum causes you to swallow more often opening the tube and causing
Every day the atmospheric pressure changes, but usually it is a slow enough
change and we swallow often enough to make the change in pressure come in
small enough increments that we do not notice the happening.
This has to do with the structure of the ear. The eardrum separates the
middle ear from the outer ear. When you go up in a plane, the atmospheric
pressure drops as you increase the elevation. The pressure outside your ear
drops faster than the pressure inside your ear. You have two small passage
from your throat called the Eustachian tubes, one leading into each middle
ear. When you open your mouth wide, i.e., drop your jaw, it opens these
passages a little wider. This allows the buildup of pressure in your middle
ear to be released and you feel a "pop." Chewing gum causes you to open and
close your mouth and to move your jaw around. Incidentally, this is also the
reason why small children get middle ear infections more often than
adults-their Eustachian tubes are shorter and at a shallower angle than they
are by adulthood. So, there is a more direct passage into the inner ear for
bacteria from the throat.
There is a long, narrow tube connecting the middle ear to the back of
the pharynx. The purpose of this tube is to equalize the pressure on
sides of the eardrum. When the pressure outside changes rapidly, air is
supposed to moves through this tube, but because the tube is narrow, it
can easily be blocked or squeeze shut. Swallowing wiggles things around
and can unblock the tube.
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Update: June 2012