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 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  2.5 cm long  S-shaped  Outer 1/3 is cartilaginous  Inner 2/3 is bone Structures  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 0 o azimuth.

The external auditory canal Combined effects of the presence of the head in a sound field. The upper solid curve represents 0 o azimuth, long dashes represent 45 o, and the short dashes represent a 90 o azimuth.

The tympanic membrane Major landmarks of the tympanic membrane

The tympanic membrane A healthy right tympanic membrane