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Consists of pinna and external auditory meatus
Outer ear
Smallest bone in the human body
Stapes
Tympanic membrane; ossicles; chain from tympanic membrane to inner ear; moves back and forth when sound hits it; different pitches move membrane more or less; sends a signal to inner ear
Middle ear
Problem transferring sound waves anywhere along pathway from the outer ear, tympanic membrane, or middle ear
Conductive
Atrophy and degeneration of stria vascularis. Arteriosclerotic vascular changes. Uniform reduction.
Strial presbycusis
Hearing and balance take place here
Inner ear
Name the ossicles
Malleus, stapes, incus
Cochlea; fluid and hair cells inside
Normal age related hearing loss; by age 65, 1/3 of population has loss; bilateral; gradual
Presbycusis
Epithelial atrophy and degeneration of hair cells. High frequency affected.
Sensory presbycusis
Sounds enter the external auditory meatus --> ossicles move --> cause fluid to move --> triggers hair cells --> convert to electrical signals --> to auditory N. --> to brain
Semicircular canals, utricle and saccule
Balance
Types of age related hearing loss
Conductive, sensorimotor and mixed
Outside ear; sound enters; determine where sound comes from; cartilage and soft tissue
Pinna
Disorder in the motion mechanism of the cochlear duct. High pitched consonants affects words beginning with s,t,g, and f
Cochlear conductive presbycusis
Cause in inner ear or sensory organs; vestibulocochlear nerve (CN VIII); auditory N; brain auditory cortex - temporal N
Sensorimotor related hearing loss
Treatment is increasing intensity of sound by speaking louder or mechanical amplification
Conductive hearing loss
Inner ear damage; louder sounds may be unclear or may sound muffled; soft sounds may be hard to hear; most common type of permanent hearing loss
Sensorimotor hearing loss
Medicine or surgery cannot fix this issue; hearing aids MAY help
Sensorimotor hearing loss
Degeneration of nerve fibers in cochlea and neuron loss along auditory pathway. Speech discrimination, tone is spared.
Words that sound alike will be confused.
Neural presbycusis
Causes can be fluid in middle ear, ear infections, poor eustachian tube function, hole in eardrum, benign tumors, cerumen in ear canal, external otitis, object stuck in outer ear, deficits in outer or middle ear formation
Causes of conductive hearing loss
Genetic or non-genetic factors; nongenetic factors - 25% of congenital hearing loss
Congenital hearing loss
Maternal infections (rubella, cytomegalovirus, herpes simplex virus), prematurity, low birth weight, birth injuries, toxins (drugs, alcohol consumed during pregnancy), complications associated with Rh factor, maternal diabetes, toxemia during pregnancy, anoxia
Nongenetic factors known to cause congenital hearing loss
Genetic factors/hereditary hearing loss is ___%
50%
Causes are illness, hereditary hearing loss, aging, head trauma, inner ear formation deficit, ototoxic medications, listening to loud noises or explosions
Causes of sensorimotor hearing loss