The human ear is divided into three main parts - the outer, middle, and inner ear. The outer ear collects sound waves and funnels them through the auditory canal to the eardrum. The middle ear contains three small bones (hammer, anvil, stirrup) that transfer vibrations from the eardrum to the inner ear. In the inner ear, the cochlea converts the vibrations into electrical signals that are sent to the brain via the auditory nerve, allowing us to perceive sound. The ear works by capturing sound waves, transmitting vibrations through the bones to the inner ear, where they are converted into nerve signals and interpreted as sound by the brain.

1. THE HUMAN EAR AND ITS
FUNCTIONS
ALVINA ANN 9C
10

2. Humans are provided with two important oragns for
sensing information carried by waves… the ears and
the eyes. The ear is the organ for hearing. It is divided
into three parts :
1. Outer ear(pinna/aurical, auditory canal)
2. Middle ear(eardrum, ossicles, eustachian tube)
3. Inner ear (cochlea, vestibule and semicircular
canal)

3. PARTS OF THE EAR

4. THE HUMAN EAR IS DIVIDED INTO THREE
SECTIONS

5. THE OUTER EAR
● Picture a satelite dish that collects
radio waves
● The outer ear is similar
● The curved formation on the outside
(the pinna) helps funnel sound down
the *ear canal* to the eardrum.

6. THE OUTER EAR
PINNA (auricle) - recieves sound waves that travel through the
auditory canal or ear canal
AUDITORY CANAL (ear canal) - acts as a funnel with an
approximate length of 2.5 and leads to the ear drum
● also protects the eardrum from shock and intrusion by external
objects

7. THE MIDDLE EAR
● the middle ear transfers the energy of
a sound wave by vibrating the *three
bones* found there
● Eardrum- is a cone shaped piece of
skin about 10mm wide
● its very sensitive
● even the slightest pressure variation
will cause it to vibrate
● seperates the outer ear from the
Middle ear

8. ● Ossicles-smallest bones in the body
● Eardrum, malleus (hammer)-long handle attached to a tiny bone that
passes vibrations from the eardrum to the anvil.
● incus(anvil) - a tiny bone that passes vibrations from the hammer to
the stirrup.
● Stapes(stirrup) - a tiny, U-shaped bone that passes vibrations from
the stirrup to the cochlea
- This is the smallest bone in the human body (it is 0.25 to 0.33 cm
long).

9. THE BONES OF THE MIDDLE EAR

10. THE INNER EAR
● Two main parts:
● cochlea
● auditory nerve

12. COCHLEA

13. THE INNER EAR
Cochlea - This is a spiral tube that is
covered in a stuff membrane
-contains thousands of hair cells attached to the
end of the organ of the auditory nerve called
ORGAN OF CORTI

14. COCHLEAR HAIR CELLS
● These tiny hair bend
because of the
vibrations caused by
the sound waves

15. THE AUDITORY NERVE
● The tiny hair cells of the cochlea
are set in motion by vibrations
● The vibrations stimulate tiny
nerve cells
● The nerve cells then send signals
along the auditory nerve to the
brain.

16. THE AUDITORY NERVE
These nerves receive the electrical impulses generated by the ear and pass this
information up to the brain so it can be interpreted.
● Semicircular Canal-three loops of fluid filled tubes that are attached to the
cochlea in the Inner ear. they help us maintain our sense of balance
● The working of human ear is in such a way that sound waves travel from the
outer ear to the middle ear, which are then transmitted to the inner ear in the
form of compressional waves
● in the Inner ear the compressional waves are converted into electric impulses
that are perceived by the brain.
● this way we can hear and differentiate various sound types.

17. HEARING
The mechanism of hearing involves the following steps:
● The sound waves passes through the auditory canal and reach the eardrum
● The vibrations produced pass through the tympanic membrane to the
tympanic cavity
● The ear ossicles in the tympanic cavity receive the vibrations and the Stapes
pushes the oval window in and out.
● This action is passed on to the organ of CORTI, the receptor of hearing,that
contains tiny hair cells that translate the vibrations into an electrical impluse
that are transmitted to the brain by sensory nerves.

18. THANK YOU!
GULF INDIAN
SCHOOL