1. II. Receiving and Interpreting Sound
A. Four Phases of Hearing
1. Sound wave enters ear (outer ear)
2. Waves vibrate ear parts (middle ear)
3. Vibrations convert to electrical nerve impulses
(inner ear & auditory nerve)
4. Nerve impulses are interpreted (brain)

2. B. Steps of Human Hearing
Outer Ear Region: Sound Collection
Pinna “catches” the sound waves and funnels them into the ear canal.
Outer Ear (Auricle)
Ear Canal
Pinna

3. Middle Ear Region: Amplifies Sound
2. Incus (anvil)
3. Stapes (stirrup)
1. Malleus (hammer)
Eardrum (tympanic membrane) vibrates ossicles (ear bones) in this order:

4. Inner Ear Region: Conversion to Nerve Impulse
Nerve impulses are picked up by auditory nerve and sent to brain.
Vibrations get passed on to the cochlea.
Tiny hairs (organ of corti) inside cochlea wiggle and convert vibrations into nerve impulses

5. Organ of Corti inside the cochlea

7. Auditory Cortex of Brain (Interprets nerve impulses)