Mother Nature has given each of you two very delicate little receivers to catch the sound waves and carry them to your brain. You know what they are—you can name them. But how are these wonderful little machines made?
You have never seen the whole of your ear. The part on the outside of the head, of course, you can easily see and feel. Sometimes you notice a deaf person put his hand behind his ear and press it forward so as to catch the sound waves better. These waves roll in at the little hole you can see, and travel along a short passage till they come to a round drum, a piece of very thin skin stretched tight like a drumhead.
Have you ever beaten a drum with a stick? You felt the drumhead quiver under the blow, did you not? Well, when the sound waves beat against the drum in the ear, it quivers and starts little waves inside the ear. Each little wave in turn beats against a little bone called the hammer; the hammer beats against another called the anvil, and this against a third called the stirrup; and the quiver of the stirrup is passed on to a little window, opening into a little room with a spiral key-board; and from this, the wave travels along a nerve to the brain. As the waves reach the brain, the brain hears. In this way we hear all sorts of sounds, from the tick of a watch to the whistle of a train.
THE WAY BY WHICH SOUND WAVES REACH THE BRAIN
A section through the right ear.
There is a sensible old saying, “Never put anything smaller than your elbow into the inner part of your ear.” Now, of course, you can’t put your elbow into such a tiny hole! So the old saying means, never put anything in. The eardrum is very thin and can easily be broken. Even a slap on the ear, or a loud sound too close to it, might crack and spoil the drum and make one deaf.
The outside ear needs careful washing; there are so many little creases that gather dirt and dust. The deep crease behind the ear, too, will become sore if it is not kept clean.
Besides cleaning your ears, you must train them to listen. Some boys and girls hear just a word or two of what is said, and then guess at the rest and think they are listening, or else ask to have it repeated. We should try to hear exactly what is said; and if we listen carefully, it will soon be much easier to understand at once.
Of course, if you really cannot hear, the doctor can tell you what is the matter, and usually can help you very much. Sometimes people become deaf simply because the throat is swollen. Indeed, most deafness comes from colds and catarrhs and other inflammations of the nose and throat. These spread to the ear through a little tube that runs up to the drum cavity from the back of the throat. Sometimes, when you are blowing your nose, you may feel your ear go “pop”; and that means that you have blown air up into the ear through this little tube. Be sure to see a doctor if you don’t hear well; and be sure, too, to tell your teacher, so that she may know why it is you do not hear what she says, and ask her to give you a seat near her, so that you can hear.