Information from Gallaudet University’s Laurent Clerc National Deaf Education Center Notes 11/3 ALL ABOUT THE EAR

 Get out your “Ear Anatomy” worksheet and be prepared to review and correct it. EAR ANATOMY

Part of the EarFunction/Definition CochleaSnail-shaped hearing organ EardrumTympanic membrane; separates outer ear from inner ear Eustachian tubeConnects the back of the nose to the middle ear and supplies it with air External auditory canal/ear canalFunnels sound from the outer ear to the eardrum Vestibular cochlear nerve/auditory nerveTransmits signals from cochlea to brain LobuleEarlobe Semicircular canalsTubes in inner ear; controls balance PinnaSticks out from the head EAR ANATOMY

 Malleus=hammer  Incus=anvil  Stapes=stirrup  Three smallest bones in the body  Help transmit sound waves from the outer ear to the cochlea THE OSSICLES

 Happens in the outer and middle ear  Affects the loudness of sounds that can be heard  Sounds are prevented from reaching the nerves in the inner ear  Can be reduced or eliminated through medical treatment  Often the problem is temporary CONDUCTIVE HEARING LOSS

 Causes:  Fluid in the middle ear from colds, allergies, poor eustachian tube function, ear infection, etc.  Impacted earwax  Presence of a foreign body (something is stuck) CONDUCTIVE HEARING LOSS

 Nerves in the inner ear are damaged  Affects the loudness and clarity of sounds that can be heard  The loss is permanent and cannot be surgically repaired  Hearing aids can help; some need them to understand spoken language and some need them to hear basic sounds SENSORINEURAL HEARING LOSS

 Causes:  Before or during birth:  Perinatal infection (in mother)- rubella, herpes, toxoplasmosis, syphilis, CMV  Heredity  Asphyxia (lack of oxygen)  Possible association with birth weight, defects of head and neck  Sometimes just unknown  Later onset  Bacterial meningitis  Ototoxicity (drug induced)  Intense or excessive noise  Physical damage to hear or ear SENSORINEURAL HEARING LOSS

 When there is a loss of hearing in both the inner and outer ear MIXED HEARING LOSS

 Hearing loss is measured in decibels (dB). The softest sounds are made at zero dB, and the loudest are 120 dB. Normal speech is around 50 dB. DEGREES OF HEARING LOSS Degree of hearing lossHearing loss range (dB HL) Normal0 to 15 Slight16 to 25 Mild26 to 40 Moderate41 to 55 Moderately Severe56 to 70 Severe71 to 90 Profound91+