audiology exam 2

• pinna
• external ear canal

• depression area of the auricle (pinna)
• serves to collect and direct sound to the external auditory meatus (opening to ear canal)

• concha
• ear canal

tympanic membrane (ear drum)

• connects nasopharynx to the middle ear
• usually closed except when yawning or swallowing
• allows fluid to drain from the middle ear
• allows us to equalize pressure in the middle ear (ears pop when going up in a plane or up the mountain)

• in cochlea
• filled with perilymph fluid
• connects scala tympani and scala vestibuli

• between scala tympani and scala vestibuli
• filled with endolymph fluid

• sensory organ of hearing
• in the scala media

organ of corti which rests on the basilar membrane in the cochlea (inner ear)

• malleus (hammer)
• incus (anvil)
• stapes (stirrup)

• to distinguish the elevation of sound
• to distinguish whether the sound is in front
• protects delicate middle ear from foreign bodies
• concha enhances the frequencies at 5000 Hz (resonant frequency of this space) and the external auditory canal enhances the frequencies at 2500 Hz (resonant frequency of this space)

• high frequencies
• enhanced high frequency sounds aid in understanding conversational speech (consonant sounds are high frequency sounds)

approx. 2500 Hz

approx. 5000 Hz

through the ossicles to the footplate of the stapes that rests in the oval window, then to the inner ear

• the middle ear
• 1. the areal ratio of the tympanic membrane to the footplate of the stapes
• 2. a complex level system existing within the ossicles

the oval window to move in, at the same time that the round window is moving out

push the round window out when the oval window is pushed in by the rocking of the stapes footplate

tonotopically

• high frequency
• tonotopic organization

• low frequency
• tonotopic organization

• so that each characteristic frequency corresponds to a place within the nerve bundle
• tonotopic organization

both place-based and timing-based codes for sound frequency

it is the shearing forces applied to the cilia in the organ of corti in response to acoustic stimulation which gives rise to electrical potentials (receptor potentials)

otoacoustic emissions or cochlea echoes

TEOAEs or transient evoked otoacoustic emissions (first measured by david kemp)

• "all or none"
• the amplitude of the response does not vary
• once it is evoked there is always a 100% response

the frequency requiring the least amount of stimulus intensity to provoke a response from the nerve fiber

ascending pathways

descending

100 to 2

• it can be recorded reliably and easily
• it can be used to estimate hearing loss
• it is useful in assisting with detection of neurological problems along the path of the auditory CNS

the lowest level at which the sound can be detected 50% of the time

2000 to 4000 Hz

20-20,000 Hz

refers to the ability of one acoustic signal to obscure the presence of another signal so it cannot be detected

• allows us to combine or integrate the neural information from both ears
• one of the key functions of the auditory CNS

localization of sound and the ability to hear in noisy situations

• autosomal (non-sex linked) dominant inheritance
• autosomal recessive inheritance
• sex linked inheritance (x-linked)

50%

a trait or disorder that arises from the individual's genes

a trait or disorder that is not attributable to genetic causes

a trait or disorder that is present at birth

• they may or may not be
• ex. maternal rubella causes hearing loss that is present at birth

• yes
• ex. hereditary types of hearing loss that don't manifest until adulthood

• deformity of the pinna
• collapsed canals
• cerumen or foreign bodies
• external otitis
• cysts and tumors

otosclerosis

a buildup of spongy bone that immobilizes the stapes footplate

• surgery (stapedectomy)
• hearing aid

• cholesteotoma (growth of skin and debris associated with perforation of eardrum)
• facial paralysis (facial nerve crosses through the middle ear)
• perforation of the tympanic membrane (hole in the eardrum)
• tympanosclerosis (plaque that forms on eardrum and ossicles causing stiffening)
• adhesive otitis media (glue ear)

• 76-95% of children will have at least one episode by the age of 6 yearsone of the most common diseases of childhood
• prevalence is highest in the first 2 years of life
• more common in males
• occurs more often in winter and spring

• antibiotics
• surgery (myringotomy and adenoidectomy)

• in utero infections (storch- syphillis, toxoplasmosis, rubella, cytomegalovirus, herpes simplex)
• low birthweight
• family history of hearing loss
• evidence of a sydrome
• craniofacial abnormalities

• mumps
• measles

• refers to damage to the nerve fibers along the ascending auditory pathways from the internal auditory meatus to the cortex
• most often due to a tumor (other causes include MS and CVA)

• hearing loss associated with aging
• sloping, high frequency, sensorineural hearing loss
• progression is usually more pronounced in men than in women

• characterized by:
• 1. an audiogram with a "4 K notch" configuration
• 2. a permanent sensorineural hearing loss in the high frequencies and near normal hearing in the low frequencies
• 3. destruction of outer hair cells in the cochlea in the base with little or no inner ear damage near the apex

usually cause high frequency hearing loss

it's the most common cause of hearing loss in children and it could be the cause of their speech problems

it helps you localize sound and allows you to focus on one specific sound and block out background noise

conductive