5.37. Hearing and the Ear http://www.ck12.org
5.37 Hearing and the Ear
- Explain how we sense sound energy and hear sounds.
- Identify the structures of the ear and their role in hearing.
This boy is cupping his hands behind his ears in order to hear better. Do you think this will help? To answer this
question, you need to know more about sound, the ear, and how we hear.
The Sounds We Hear
Soundis a form of energy that travels in waves through matter. The ability to sense sound energy and perceive
sound is calledhearing. The organ that we use to sense sound energy is the ear. Almost all the structures in the ear
are needed for this purpose. Together, they gather sound waves, amplify the waves, and change their kinetic energy
to electrical signals. The electrical signals travel to the brain, which interprets them as the sounds we hear.
TheFigure5.73 shows the three main parts of the ear: the outer, middle, and inner ear. It also shows the specific
structures in each part of the ear. The roles of these structures in hearing are described below and in this animation:
http://www.medindia.net/animation/ear_anatomy.asp.
Outer Ear
The outer ear includes the pinna, ear canal, and eardrum.
- The pinna is the only part of the ear that extends outward from the head. Its position and shape make it good
at catching sound waves and funneling them into the ear canal. - The ear canal is a tube that carries sound waves into the ear. The sound waves travel through the air inside the
ear canal to the eardrum.