kidsjudge

A Diagram of the Ear
(taken from http://www.howstuffworks.com/hearing4.htm)

What is an eardrum?
The eardrum is a thin, cone-shaped piece of skin, about 10 millimeters (0.4 inches) wide.

How do we hear?
Sound travels through the air and into our ear canal. Once in the ear canal, it reached the ear drum. The ear drum vibrates and sends a message to the brain. The ear drum and the message to the brain combine to help us hear the sound.

Sound hitting the eardrum causing it to vibrate (taken from
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/waves/edl.html)

� � � � � � � � � � � � � � � � What is an ear infection and a perforated ear drum ?

� � � � � � � � � � � � � � � � � �An ear infection happens when bacteria get � � � � � � � � � � into your middle ear, which is a small pocket � � � � � � � � � of air about the� size of a grape located � � � � � � � � � � � behind the eardrum. After the bacteria enter � � � � � � � � � � your ear, it makes lots of pus, a thick liquid � � � � � � � � � that contains bacteria-fighting cells. When � � � � � � � � � � the pus builds up, your ear starts to feel � � � � � � � � � � � like a balloon that is ready to pop, which can � � � � � � � � � really hurt. � � � � � � � � � � �� A perforated eardrum happens when your gets a � � � � � � � � � hole it in. This hole in your eardrum does not � � � � � � � � � allow you to hear as well as you would if you had � � � � � � � a normal eardrum. There are several ways you can � � � � � � � � perforate your � � eardrum: with a cotton-tipped � � � � � � � � swab, by hitting the ear with an open hand, or � � � � � � � � � after a loud explosion or other loud noise.

How to Make Your Own Eardrum

It's easy to make a model of the eardrum (also called the "tympanic membrane") and see how sound travels through the air. Just stretch a piece of plastic wrap over a large bowl or pot (any container with a wide opening will work). Make sure the plastic wrap is stretched tightly over the container. The plastic represents the eardrum. Place about 20-30 grains of uncooked rice on the top of
the plastic wrap. Now you need a noise maker. A tin cookie sheet or baking tray works well. Hold the cookie sheet close to the plastic wrap. Hit the cookie sheet to create a "big bang" noise and watch the rice grains jump.

The "big bang" produces sound waves (changes in air pressure) that cause the plastic sheet to vibrate which causes the rice grains to move. Sound waves vibrate the eardrum in much the same way.

Materials:

Plastic wrap
Container with wide opening
Uncooked rice (any other small grain will work)
Tin cookie sheet (or other noise maker) �

Beating on the Eardrum