1. Chapter 15 section 3 Sight and Hearing
* Describe how the ears sense sound and help maintain balance.

2. B. Hearing and Balance
* Ears convert sound to nerve impulses that your brain
interprets.
1. How Sound is Produced
-Sound are vibrations that travel as waves.

3. 2. The External Ear
-shaped like a funnel

5. 3. The Middle Ear
-Sound waves enter the ear canal to the eardrum
-there are three small bones
anvil, stirrup, hammer
-act as a series of levers that transfer vibrations from one place to another

6. 4. The Inner Ear
-The stirrup vibrates against
a membrane called the labyrinth.
-The membrane channels the
vibrations into a fluid found in
the cochlea.

7. -Fluid in the cochlea stimulate the
sensory neurons nearby.
-Sensory neurons then send nerve
impulses to the cerebrum through
the auditory nerve.

8. 6. The Inner Ear and Balance
-Semicircular canals control your sense of balance.
-are full of fluid
-lines with tiny cells with hairlike extensions
-when the head moves, the extensions bend.
-sensory neurons pick up the bending and send impulses to the cerebellum