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Anatomy and physiology of the ear
External ear

Pinna (auricle) & External auditory meatus

Function: Localization
Middle ear

Tympanic membrane,
middle ear cavity, &
ossicles (malleus, incus,
stapes)

Function: Compensating
for impedance mismatch
between air and fluid
Three main components of middle ear
transfer function
1.
Area difference between tympanic
membrane and stapes footplate
2.
Ossicular level action
3.
Buckling movement of tympanic membrane
Inner ear

Bony and
membraneous
labyrinth

Vestibular system
(Semicircular canals &
Vestibule)

Auditory system
(Cochlea)
Macrostructure of cochlea
Microstructure of cochlea
Function of cochlea

Frequency analysis of incoming sound: Basilar
membrane acts as a series of bandpass filters

Transduction of mechanical vibration to
electrochemical/neural impulses: Forward
transduction

Outer hair cells: Responsible for cochlear
amplifier (Backward transduction)
Pathways of sound

Air conduction (AC): Transmission through
outer, middle, inner ear, and higher up.

Bone conduction (BC): Transmission that
stimulates the inner ear directly through
mechanical vibration of the skull.
CONDUCTIVE
SENSORINEURAL
Normal
hearing
Outer ear
Middle ear
Inner ear
Auditory nerve
Conductive
hearing loss
Outer ear
Middle ear
Inner ear
Auditory nerve
Sensorineural
hearing loss
Outer ear
Middle ear
Inner ear
Auditory nerve
Mixed
hearing loss
Outer ear
Middle ear
Inner ear
Auditory nerve