20.2. Hearing Sound http://www.ck12.org
20.2 Hearing Sound
Lesson Objectives
- Explain how we hear sound.
- Relate loud sounds to hearing loss.
- State how hearing can be protected.
Introduction
The organ that we use to hear sound is the ear. Almost all the structures in the ear are needed for this purpose.
Together, they gather and amplify sound waves and change their energy to electrical signals. The electrical signals
travel to the brain, which interprets them as sound.
How We Hear
Figure20.7 shows the three main parts of the ear: the outer, middle, and inner ear. It also shows the specific
structures in each part. The roles of these structures in hearing are described below and in the animations at these
URLS:
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/117492Outer 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.