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Anatomy and physiology of the earAnatomy and physiology of the ear
External earExternal ear
Pinna (auricle) & External auditory meatusPinna (auricle) & External auditory meatus
Function: LocalizationFunction: Localization
Middle earMiddle ear
Tympanic membrane, Tympanic membrane, middle ear cavity, & middle ear cavity, & ossicles (malleus, ossicles (malleus, incus, stapes)incus, stapes)
Function: Function: Compensating for Compensating for impedance mismatch impedance mismatch between air and fluidbetween air and fluid
Three main components of middle ear Three main components of middle ear transfer function transfer function
1.1. Area difference between tympanic Area difference between tympanic membrane and stapes footplatemembrane and stapes footplate
2.2. Ossicular level actionOssicular level action
3.3. Buckling movement of tympanic Buckling movement of tympanic membranemembrane
Inner earInner ear
Bony and Bony and membraneous membraneous labyrinth labyrinth
Vestibular system Vestibular system (Semicircular (Semicircular canals & Vestibule) canals & Vestibule)
Auditory system Auditory system (Cochlea)(Cochlea)
Macrostructure of cochleaMacrostructure of cochlea
Microstructure of cochleaMicrostructure of cochlea
Function of cochleaFunction of cochlea
Frequency analysis of incoming sound: Frequency analysis of incoming sound: Basilar membrane acts as a series of Basilar membrane acts as a series of bandpass filtersbandpass filters
Transduction of mechanical vibration to Transduction of mechanical vibration to electrochemical/neural impulses: Forward electrochemical/neural impulses: Forward transductiontransduction
Outer hair cells: Responsible for Outer hair cells: Responsible for cochlear cochlear amplifieramplifier (Backward transduction) (Backward transduction)
Pathways of soundPathways of sound
Air conduction (AC): Transmission through Air conduction (AC): Transmission through outer, middle, inner ear, and higher up.outer, middle, inner ear, and higher up.
Bone conduction (BC): Transmission that Bone conduction (BC): Transmission that stimulates the inner ear directly through stimulates the inner ear directly through mechanical vibration of the skull.mechanical vibration of the skull.
Normal hearing
Conductivehearing loss
Sensorineuralhearing loss
Mixedhearing loss
Outer ear Middle ear Inner ear Auditory nerve
Outer ear Middle ear Inner ear Auditory nerve
Outer ear Middle ear Inner ear Auditory nerve
Outer ear Middle ear Inner ear Auditory nerve
CONDUCTIVE SENSORINEURAL