..................The Ear..................

Your ear is a fascinating part of your body. It is able to process frequencies from 20 - 20,000Hz! The outer part of the ear which you see is your pinna. The pinna is specially designed to help transform sound waves in the air, making them better for recognition. Inside your ear there is the tympanic membrane, which is commonly referred to as your eardrum. When the sound waves hit the tympanic membrane, it vibrates like a drum. This vibration stimulates three very small bones located further down your ear called the malleus, incus, and stapes. These three bones act like a relay of vibrations into your cochlea. The cochlea looks like a snail shell you see on the beach. Inside are many tiny hair cells which also vibrate, sending information to your Vestibulocochlear nerve, which goes to your brain!



..................Activity..................

First the girls and their parents/ guardians are going to listen to different frequencies of sound through the use of a tone generator. Some frequencies they will be able to hear and some they will not. This will show the girls the wide range of frequencies that the ear is capable of hearing.  It will also show how this range varies with age as their guardians will most likely not be able to hear as well as them.

Next, we're going to explain to the girls how the incus, stapes, malleus move and allow us to hear. We're going to give each girl a plastic bowl and wrap SaranWrap across the top of the bowl. Then we will put raw rice on the top of the SaranWrap. We will turn on music which will allow the rice to vibrate, demonstrating how the ear works. Then we will tell the children to put shaving cream on top of the rice, which will demonstrate what happens when people get an ear infection.

Finally, to demonstrate how the ear localizes a sound, we will blindfold one girl and place her in the center while all the girls sit around her in a circle.  While blindfolded we will point to one girl and tell her to say the name of the person in the middle.  The blindfolded girl will then try to point to where the sound was coming from and identify who said it.  Then we will explain how different frequencies allow us to differentiate sound and tell where it is coming from.