Sound & Hearing
p. 618-620
1. How do ears enable people to
hear?
• Ears respond to the stimulus of sound
vibrations.
• They convert this stimulus to nerve
impulses that your brain interprets.
sound
nerve impulses
Outer Ear
Auricle
(or Pinna)
-collects
sound
waves
Auditory
Canal
-directs sound
waves toward
eardrum
Auditory
Canal
Outer Ear
Label the parts of the ear and
relate to their function.
• A. Outer ear – act as funnel, collecting
sounds and sending them to eardrum
Outer ear
• B. Eardrum (tympanum) – vibrates when
sound waves strike it & pass it to middle
ear
Auricle
(or Pinna)
Auditory
Canal
Auditory
Canal
Eardrum
(Tympanum)
-vibrates
• C. Middle Ear – hammer, anvil, stirrup;
amplifies sound vibrations and transfers
them to the cochlea
Middle ear
Anvil
Hammer
Auricle
(or Pinna)
Auditory
Canal
Stirrup
Auditory
Canal
Eardrum
(Tympanum)
• D. Eustachian tube – connects middle ear
to throat; ensures pressure inside is equal
to outside.
Anvil
Hammer
Auricle
(or Pinna)
Auditory
Canal
Stirrup
Auditory
Canal
Eardrum
(Tympanum)
Eustacian
Tube
-drains ear
-equalizes
pressure
• E. Cochlea – snail shaped tube with
receptors that respond to sound – convert
vibrations to nerve impulses
Anvil
Hammer
Auricle
(or Pinna)
Auditory
Canal
Cochlea
Auditory
Canal
Eardrum
(Tympanum)
Stirrup -converts
vibration
to nerve
impulses
Eustacian
Tube
• F. Auditory nerve – sends nerve impulses
from cochlea to cerebrum; brain then
translates them into sounds we understand
Anvil
Auditory Nerve
-sends impulse
to cerebrum
Hammer
Auricle
(or Pinna)
Auditory
Canal
Cochlea
Stirrup
Auditory
Canal
Eardrum
(Tympanum)
Eustacian
Tube
2. How do ears maintain your
balance?
• 3 semicircular canals
in inner ear, filled with
fluid that moves as
you move
• Fluid bends hair like
extensions of cells
and sends nerve
impulses to the
cerebellum
Anvil
Hammer
Semicircular Canals
-maintain balance
Auditory Nerve
Auricle
(or Pinna)
Auditory
Canal
Cochlea
Stirrup
Auditory
Canal
Eardrum
(Tympanum)
Eustacian
Tube