Transcript The Outer Ear

CSD 3103
anatomy of speech and hearing
mechanisms
Hearing mechanisms
Fall 2008
The Outer Ear
The outer ear
Cross section of the external ear
Major structures of The
outer ear
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Pinna or auricle
External auditory meatus or external ear canal
Tympanic membrane or eardrum
The pinna
 Size
and shape varies from person to person
 Gathers sound from the environment and
funnels it to the eardrum
 Made entirely of cartilage and covered with skin
The pinna
Major landmarks
on the pinna
The pinna
Geographic landmarks for the pinna
Resonance properties of
The pinna
Resonance effects of the helix (flange) and concha in the most
favorable azimuth position. The helix has a 2 dB peak at 4000 Hz.
The concha has a 9 dB increase at 5300 Hz.
The pinna
The pinna and its
major landmarks
The external auditory
canal
Cross section of the external ear
The external auditory
canal
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2.5 cm long
S-shaped
Outer 1/3 is
cartilaginous
Inner 2/3 is bone
Structures
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Sebaceous glands
Hair follicles
Osseocartilaginous
junction
The external auditory
canal
Resonance effects of the external auditory meatus, shown as the
ratio of the SPL at the eardrum to the SPL at the entrance of the
ear canal at 0o azimuth.
The external auditory
canal
Combined effects of the presence of the head in a sound field. The
upper solid curve represents 0o azimuth, long dashes represent
45o, and the short dashes represent a 90o azimuth.
The tympanic membrane
Major landmarks of the tympanic membrane
The tympanic membrane
A healthy right tympanic membrane