The document summarizes the structure and function of the human ear. It describes the three main parts of the ear - outer, middle, and inner ear. Sound waves enter the outer ear and cause the eardrum and three tiny bones of the middle ear to vibrate. These vibrations are transmitted to the fluid-filled inner ear, causing waves that stimulate hair cells and nerves to send signals to the brain. The basilar membrane of the inner ear helps the brain perceive pitch and loudness of sounds.

1. Auditory Sense (Hearing) pg 6

2. Structure of the Ear
Outer Ear

3. Structure of the Ear
Outer Ear
• Auricle (pinna): fleshy, visible part of the
ear. Made of elastic cartilage. Helps
collect sound waves

4. Structure of the Ear
Outer Ear
• Auricle (pinna): fleshy, visible part of the
ear. Made of elastic cartilage. Helps
collect sound waves
• External auditory canal (meatus): Tube
about 2.5 cm long. Contains hairs and
glands that produce cerumen

5. Middle Ear

6. Middle Ear
• Tympanic membrane (eardrum):
Separates outer ear from middle ear.
Sound waves cause it to vibrate

7. Middle Ear
• Tympanic membrane (eardrum):
Separates outer ear from middle ear.
Sound waves cause it to vibrate
• Auditory ossicles: 3 tiny bones– malleus
(hammer), incus (anvil), and stapes
(stirrup). Transmit vibrations from the
eardrum to the inner ear. Malleus is
attached to the eardrum. Stapes is
attached to the oval window

8. Middle Ear
• Tympanic membrane
• Auditory ossicles
• Eustachian tube: Connects the middle
ear with the upper part of the throat.
Allows air pressure to equalize on both
sides of the eardrum

9. Inner Ear

10. Inner Ear
• Vestibule and Semicircular canals:
function in the sense of equilibrium

11. Inner Ear
• Vestibule and Semicircular canals:
function in the sense of equilibrium
• Cochlea: functions in hearing. Resembles
a snail’s shell. Contains the organ of
Corti, which sits on the basilar
membrane and contains numerous hair
cells that are linked to neurons

12. Physiology of Hearing

13. Physiology of Hearing
1. Sound waves cause the tympanic membrane
to vibrate

14. Physiology of Hearing
1. Sound waves cause the tympanic membrane
to vibrate
2. Malleus, incus, and stapes transfer vibrations
to the oval window

15. Physiology of Hearing
1. Sound waves cause the tympanic membrane
to vibrate
2. Malleus, incus, and stapes transfer vibrations
to the oval window
3. Movement of the oval window causes waves
to form in the fluid within the cochlea

16. Physiology of Hearing
1. Sound waves cause the tympanic membrane
to vibrate
2. Malleus, incus, and stapes transfer vibrations
to the oval window
3. Movement of the oval window causes waves
to form in the fluid within the cochlea
4. The waves cause the basilar membrane to
vibrate, which bends the hair cells on the
organ of Corti

17. Physiology of Hearing
1. Sound waves cause the tympanic membrane
to vibrate
2. Malleus, incus, and stapes transfer vibrations
to the oval window
3. Movement of the oval window causes waves
to form in the fluid within the cochlea
4. The waves cause the basilar membrane to
vibrate, which bends the hair cells on the
organ of Corti
5. Bending stimulates nerve impulses, which
are transmitted to the brain

18. Pitch and Loudness
• Pitch: Each region of the basilar
membrane is “tuned” to a particular
pitch. High pitched sounds cause
vibrations at the base of the membrane
while low pitched sounds cause
vibrations at the apex

19. Pitch and Loudness
• Pitch: Each region of the basilar
membrane is “tuned” to a particular
pitch. High pitched sounds cause
vibrations at the base of the membrane
while low pitched sounds cause
vibrations at the apex
• Loudness: Loud sounds cause larger
vibrations in the basilar membrane,
which leads to more nerve impulses
reaching the brain