1. The Ear
Biology 12

2. What is sound? A form of energy which travels in the form of a wave.
The outer ear or pinna collects the sound and directs it into the auditory canal.
Hearing begins when sound waves hit the ear drum a.k.a. the tympanic membrane.
These vibrations are passed on to the 3 bones of the middle ear.

3. The Middle Ear They are called: Malleus or hammer Incus or anvil
Stapes or stirrup
These bones concentrate and amplify the vibrations.

4. The Middle Ear

5. The Inner Ear
The cochlea is shaped like a snail shell and is filled with fluid.
The cochlea is lined with cilia which react to the fluid vibrations and converts them into electrical impulses.

6. Temporal Lobe of Cerebrum
The nerve impulses created in the cochlea travel via the auditory nerve to the temporal lobe of the cerebrum.
The brain interprets this information as sound. It can distinguish pitch and loudness.

7. Balance and the Inner Ear
Did you know that keeping your balance is the job of the inner ear?
A structure made of 2 canals is filled with a gel like substance. When you bend forward, this gel slips ahead and bends little cilia to let you know that you are off balance.
When your head is upright, the cilia do not move and you feel balanced.

8. Class Activity Biology 12 Text Page 449
In small groups, read the case study.
Prepare a list of points.
Answer questions a) and b).
Suggest improvements and prepare to defend your viewpoint in class.