What an excellent question! Hey, you know what? I was just in Paris last week on a trip, and I rode the Eiffel Tower elevator to the very top floor. On the way up, I felt my ears pop suddenly! I have also had a painful ear ache when I went SCUBA diving with a cold last year...can you figure out why my ears popped on the elevator and hurt when I went diving? (see below for good clues...)

When I typed your question in on the Google search engine (http://www.google.com), which one of my favorite search engines for surfing the web, Google took me directly to 2 really great web sites on this topic!:

One is the Howstuffworks (you won't want to leave this cool site!), and the other is from Trivia Planet . A lot of people had the very same question as you, and it is a very popular topic! Be sure to check out the picture of our ears (inner and outer) on the Howstuffworks site

Here is a short summery of what is happening.

You may already know that the ear is made of the ear canal with the eardrum at the end and a hollow space called middle ear on the other side of the eardrum. The hollow space in the middle ear is filled with air. When the air pressure in the middle ear is the same as the air pressure in the ear canal, everything is fine. But when the pressure outside our ear changes (diving in water, going up an elevator, increase altitude in an airplane) the pressure in the middle ear has to change too. This means, if the outside the ear pressure decreases, the middle ear pressure has to increase. This can be very painful if you do not equalize the pressure. To do this, take a breath, hold your nose and blow into your nose. You will hear your ears pop and the pain should go away. This procedure increases the pressure in the back of your throat and forces the tubes that are in the back of our throat to open and thus equalizing the pressure.