CSD 3103anatomy of speech and hearing mechanismsHearing mechanismsFall 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
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
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