Outer ear

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Outer ear
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External and middle ear, opened from the front. Right side.
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The auricula. Lateral surface.
Latin auris externa
Gray's p.1033
MeSH External+Ear
Dorlands
/Elsevier
Outer ear
TA A15.3.01.001
Anatomical terminology


The outer ear is the external portion of the ear, which consists of the pinna and external auditory meatus. It gathers sound energy and focuses it on the eardrum (tympanic membrane).

Structure[edit]

Pinna[edit]

Main article: pinna (anatomy)

The visible part is called the pinna, also known as the auricle. It is composed of a thin plate of yellow elastic cartilage, covered with integument, and connected to the surrounding parts by ligaments and muscles; and to the commencement of the external acoustic meatus by fibrous tissue. Many mammals can move the pinna (with the auriculares muscles) in order to focus their hearing in a certain direction in much the same way that they can turn their eyes. Most humans, unlike most other mammals, do not have this ability.[citation needed]

Ear canal[edit]

Main article: Ear canal

From the pinna the sound pressure waves move into the ear canal, also known as the external acoustic meatus a simple tube running through the middle ear. This tube leads inward from the bottom of the auricula and conducts the vibrations to the tympanic cavity and amplifies frequencies in the range 3 kHz to 12 kHz.

Function[edit]

One consequence of the configuration of the outer ear is selectively to boost the sound pressure 30- to 100-fold for frequencies around 3 kHz. This amplification makes humans most sensitive to frequencies in this range — and also explains why they are particularly prone to acoustical injury and hearing loss near this frequency. Most human speech sounds are also distributed in the bandwidth around 3 kHz.[1]

References[edit]

  1. ^ Purves, Dale, George J. Augustine, David Fitzpatrick, William C. Hall, Anthony-Samuel LaMantia, James O. McNamara, and Leonard E. White (2008). "Chapter 13". Neuroscience. 4th ed. Sinauer Associates. p. 317. ISBN 978-0-87893-697-7.