We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
SPEECH, MUSIC, AND HEARING 243
inward a little channel called the "canal," along which the sound waves pass. At its inner end the canal is closed entirely by a piece of thin, delicate membrane which is exactly like a drumhead. It is appropriately called the drum of the ear, or tympanum. If we could see beyond the eardrum, we should find that it made one of the walls of a little space, or chamber, hollowed out inside one of the bones of the head. This second space is known as the middle ear. The bone in which it, and also the inner ear, lie, is called the petrous bone, and is the hardest in the whole body. This is especially interesting because a hard bone must undoubtedly conduct waves of sound very much better than a soft one, and the petrous thus illustrates a fundamental in acoustics. The middle ear is filled with air, which is fed from the throat. For the purpose there runs from the back of the throat, on each side, a little tube which goes to the middle ear and conveys air to it. In the middle ear is a minute chain of three small bones, much the smallest in the body, which are known as the hammer, the anvil, and the stirrup. The handle of the hammer lies against the drum of the ear. The hammer is jointed to the anvil and the anvil to the stirrup, and the foot of the stirrup lies against another sort of drum which leads to the inner ear. Needless to say the bones take their names from objects they resemble.
This chain of bones carries the sound waves across the middle ear. Every time a sound wave causes the drum of the ear to vibrate it sets in motion the hammer bone, which is fastened to it, and so the vibration goes on. Lastly, there are two very tiny muscles which pass into the middle ear. These have opposite uses and are called to action when we want to hear a sound more acutely or less acutely. One is so arranged that when it pulls it tightens the drum of the ear. That makes the drum vibrate more energetically, with the result of better hearing. The