How the Ear Works

Thanks to http://health.howstuffworks.com/hearing5.html

The Ear

(is divided into three sections:)

Outer

Middle

Inner

Outer

• Has 2 portions.
• First is Pinna , the skin covered flabby cartilage that is visible.
• Pinna Function : Protect Eardrum , Collect Soundwave through ear canal.
• Second is Auditory Ear Canal(meatus) .
• Function : secrete wax , passage for soundwave.
• Modified sweat glands.

Middle

• Ear Drums

1. Also known as (tympanic Membrane)
2. Situated between ear canal and middle ear
3. Tensor tympani muscles > they pull the eardrums inwards > (rigid , sensitive).
4. Tensor tympani muscles partners with stapedius muscle protects human from loud and high pitch noise.
5. They also explains why we can hear ourselves when we talk in a crowded area.

• 3 Ossicles ( Tiny bones ) Bones

1. Malleus - Hammer
2. Incus - Anvil
3. Staples - Stir up

Ossicles vibrates sends force to the Staples' FacePlate ( see below ).

The surface area of eardrums is 55 sq millimeters, compared to staple's faceplate (2 sq millimeters )

When a vibrating force acts on eardrums. The eardrums pressure transfered to staple becomes relatively high as nearly as 22X it's previous pressure.

• Inner Ear

1. Consists of ( cochlea , semi-circular canals X3 , vestibule (labyrinth)

Cochlea

• Function : Physical vibration > Electrical Signal
• cochlea shape is like a snail's shell. ( For the above illustration, imagine it as a horizontal plane)
• Cochlea has basilar membranes ( 20,000-30,000) reed-like fibres.
• Basilar Membrane are like resonating Tuning Forks
• As a vibration is being transmitted into the cochlea... it produce a ripple effect like a pond inside the cochlea.
• Because of various frequency a sound may produce. As long as it travels further deeper into the cochlea, it will meet a specific frequency that causes an escalation of amplitude , releasing energy in form of electric. ( Resonance )
• Definition of Resonance : vibration of large amplitude produced by a relatively small vibration near the same frequency of vibration as the natural frequency of the resonating system

Cochlea and Basilar Membrane helps us Distinguish Different Frequencies or Tones.