Auricle (Pinna): captures and directs sound down the ear canal Ear canal (External Auditory Meatus): 3/4" long; conducts sound waves toward the eardrum; lined with CILIA (hairs) that filter out dust; contains cells that secrete CERUMEN (wax) which prevents drying out and insects.

Tympanic membrane (ear drum): where ear canal ends, pushes in

MECHANICAL SYSTEM -- begins at tympanic membrane -- 3 tiny bones in space called OSSICLES: MALLEUS, INCUS & STAPES (HAMMER, ANVIL & STIRRUP) -- air-filled space -- EUSTACHIAN TUBE: connects middle ear with nose/throat -- allows for equalization of air pressure on both sides of eardrum -- swallowing, yawning & chewing open it & let air in -- acoustic energy converted to mechanical -- tympanic membrane vibrates & sets the 3 ossicles in motion -- ends w/ footplate of Stapes in OVAL WINDOW

Structures: COCHLEA (hearing) & SEMICIRCULAR CANALS (balance) -- fluid filled -- HYDRAULIC SYSTEM

Cochlea: contains sensory nerve endings for hearing, converts hydraulic energy (fluid motion) into neural impulses interpreted as sounds by CNS, shaped like a snail shell, 2½ turns

ORGAN OF CORTI: contains hair cells (if destroyed, can't grow back) which are embedded in Tectorial Membrane

• Most prevalent handicap worldwide
• can be UNILATERAL (one ear) or BILATERAL (both ears)
• CONGENITAL: present at time of birth or ACQUIRED
• can be temporary, progressive or permanent
• CONDUCTIVE or SENSORY/NEURAL

Conductive

hearing loss

involves outer and/or middle ear -- EXTERNAL BLOCKAGE: build up of wax or foreign object in canal

PERFORATED EARDRUM: hole or tear; caused by injury, sudden pressure change or infection

GENETIC and CONGENITAL ABNORMALITIES

OTITIS MEDIA: middle ear infection, most common ear problem

OTOSCLEROSIS: affects mobility of 3 bones

hearing aid not needed if problem can be treated medically/surgically

Sensory / Neural

hearing loss

damage to inner ear (cochlea &/or nerve fibers of viii cran. n: auditory nerve) -- HEREDITARY: usually present at birth (cochlear: inherited or syndrome) -- PERINATAL COCHLEAR: disruption in normal birth -- TRAUMA INDUCED: severe head blow, accident, stroke, brain hemorrhage -- TUMORS -- VASCULAR ACCIDENTS: hbp or heart disease -- DRUG INDUCED: aspirin, some antibiotics, diuretics, chemo meds -- VARIAL & BACTERIAL: mumps, meningitis, encephilitis, rubella by expectant mother -- MENIERE'S DISEASE: syndrome w/ fluctuating hearing loss, vertigo, & TINNITUS (ringing/buzzing in ears/head) -- NOISE: #1 cause

Prelinguistic

hearing loss

• loss occurs prior to acquiring speech
• (aural habilitation)

Postlinguistic

hearing loss

• loss occurs after acquiring speech
• try to keep language
• (aural rehabilitation)

• behind-the-ear (BTE)
• in-the-ear (ITE)
• in-the-canal (ITC)
• completely-in-the-canal (CIC)
• body worn aid
• Hearing aids DON'T make hearing normal(not like glasses)