ABOUT SOUND: Sound waves are pressure waves, the result of a vibrating object that creates a disturbance in the surrounding air. For example, the ringer in a telephone vibrates quickly to create its distinctive tone As the ringer moves in one direction, the air molecules push closer together - an effect known as compression -- while leaving a space between themselves and the ringer in the opposite direction ę an effect called rarefaction. The motion disturbs the neighboring molecules in turn, creating an outward ripple effect that carries the sound around the room, much as a stone cast in a quiet pond will cause waves to ripple outward from the spot where it was dropped.
ABOUT THE EAR: The ear has three primary sections: the outer, middle and inner ear. All three work together to help the human body detect and process sound. Sound is simply vibrations in the air. The outer ear picks up sound waves, which travel through the outer ear canal and strike the eardrum. When this happens, the drum begins to vibrate in response. This in turn moves three tiny bones, called the hammer, the anvil and the stirrup. They help transmit the sound vibrations to the inner ear, which is filled with liquid and lined with thousands of tiny hairs that move in response to the sound vibrations. This changes the vibrations into nerve signals, so the brain can recognize and interpret them.
The Acoustical Society of America contributed to the information contained in the TV portion of this report.