Audiometry
what range of frequency (hz) AND intensity (dB) is the human ear sensitive to?
20 - 20,000 Hz and 0 - 120+ dB
what is the name of the cranial nerve that carries auditory sensory information from the cochlea to the central nervous system?
vestibulocochlear nerve, cranial nerve VIII
inner ear disorder characterized by episodic symptoms of vertigo, sensorineural hearing loss, tinnitus, and aural fullness; degenerative disease that usually start unilaterally
meniere’s disease
how does the middle ear make up for the change in impedance that happens as the signal moves from air in the outer ear to fluid in the inner ear? (there are two ways)
(1) the difference in surface between tympanic membrane and footplate of stapes (22 to 1) increases the pressure on the smaller surface and thus increases the signal 23-24 dB, and (2) the lever action of the ossicles which increase the signal by a factor of 1.8
determine the disorder from the following:
audiogram: bilateral sensorineural hearing loss; noise notch at roughly 4000 Hz
tympanogram: Type A
acoustic reflexes: none
client: 50 years old
acoustic trauma/NIHL
how do sound waves travel to the cochlea in air conduction versus bone conduction?
in air conduction sound waves travel via the eardrum and the ossicles and oval window to the cochlea and in bone conduction sound waves travel via the bone (mastoid) to the cochlea
What parts of the cochlea (basilar membrane) correspond to high frequencies and low frequencies?
the base the BM is at its narrowest and most stiff (high-frequencies) and at the apex it is at its widest and least stiff (low-frequencies)
A disorder of the outer ear characterized by a bacterial or fungal infection of the external auditory canal and symptoms of otalgia (earache), itching, and aural fullness; very common (200,000+ cases per year in U.S.)
external otitis / otitis externa
what two aspects of the middle ear does tympanometry evaluate/measure? what type of hearing loss is consistent with abnormal tympanometry results?
the pressure in the middle ear and the mobility of the eardrum; abnormality at tympanometry almost always with conductive component in the hearing loss, so conductive or mixed hearing loss)
determine the disorder from the following:
audiogram: bilateral sloping mild to severe sensorineural hearing loss; sharper decline towards higher frequencies
tympanogram: Type A
word reception scores: poor
client: 75 years old
presbycusis
describe the weber and rinne tuning fork tests; what is a normal result in these tests and what can an abnormal result in these two tests tell us about the functioning of the ears?
weber test: tuning fork test that evaluates bone conduction of sound in both ears at the same time; the fork is placed in the middle of the forehead; a normal result would be if the sound is heard equally (loud) on both sides; if the client hears the signal louder in the defective ear it indicates a conductive hearing loss in the defective ear and if the client hears the signal louder in the normal ear it indicates a sensorineural hearing loss in the defective ear
rinne test: tuning-fork test that compares hearing by air conduction with hearing by bone conduction; fork is placed on the mastoid and then in front of the EAC; a normal result occurs when the sound heard outside the ear is louder than the sound heard when the tuning fork end is placed against the mastoid process; a normal result indicates normal hearing or SNHL; if the sound heard outside the ear is softer than the sound heard when the tuning fork end is placed on the mastoid process then this indicates a conductive hearing loss
This part of the middle ear dampens the vibrations of the stapes by pulling on the neck of the stapes; it prevents excessive movement of the stapes which helps to control the amplitude of sound waves and protect the inner ear from high noise levels
stapedius muscle
an in-growth of epithelium in the middle ear as a result of retracted/perforated eardrum; the growth erodes middle ear structures and may cause dysfunction of facial/vestibular/auditory nerves; there is a congenital and an acquire type
cholesteatoma
list the 5 classifications of tympanograms and the disorder that is characteristic of each tympanogram
type A = normal
type As = reduced peak, indicating typanosclerosis
type Ad = increased peak, ossicular chain dysfunction
type B = flat, middle ear infection (otitis media)
type C = peak moved to left, eustachian tube dysfunction
determine the disorder from the following:
audiogram: unilateral (right) flat moderately severe sensorineural hearing loss
tympanogram: Type A
word recognition scores: impaired
acoustic reflexes: present
client: 45 years old
Meniere’s disease
what are three of the five reasons for doing speech audiometry?
confirm pure-tone hearing thresholds, complaints with speech understanding, differential diagnosis, decision to go for hearing aid fitting/cochlear implant, determining disability
What are four of the five major functions of the pinna?
sound collection, amplification (high frequency), direct sound into ear canal, protection, determine the direction of the sound source
disorder of the inner ear which occurs in-utero; characterized by low birth weight, psychomotor deficits, blindness, and severe to profound sensorineural hearing loss
cytomegalovirus (CMV)
what parts of the auditory pathway do the I, III, and V peaks in an auditory brainstem response (ABR) correspond to? Generally, at what time (ms) do these peaks occur?
I at 1.64ms: distal part of the auditory nerve (dendrites of the auditory nerve fibers)
III at 3.58ms: cochlear nucleus (medulla/brainstem)
V at 5.72ms: inferior colliculus (midbrain)
determine the disorder from the following:
audiogram: flat mild to moderately severe bilateral conductive hearing loss (normal bone conduction)
tympanogram: Type B
word recognition scores: normal
acoustic reflexes: none
client: 10 years old
otitis media
when looking at the S-shaped curve in a performance-intensity function (speech audiogram) what will the curve look like if a patient has both a sensation loss and a discrimination loss? what do these losses tell us about the hearing of the individual and what type of hearing loss (conductive, sensorineural, mixed) might they have?
a sensation loss will cause the s-shaped curve to shift to the right indicating that the intensity (dB) of the signal must be increased for speech understanding; a discrimination loss will cause to top of the s-shaped curve to be lowered indicating that no matter how much the intensity (dB) is increased speech understand will never be 100%; the combination of a sensation loss with a discrimination loss is typical of a sensorineural or mixed hearing loss
What are the five general steps of transmitting sound waves through the cochlea (from mechanical vibrations into electrical signals)?
in and out movements of the stapes footplate => in and out movement of round window => pressure wave in cochlea (traveling wave) => displacement of stereocilia of haircells in organ of corti (scala media)=> chemical reaction in haircell =>
disorder of the auditory nerve/pathways which is a rare genetic condition that manifests symmetric, benign tumors in the region of the cranial nerve VIII (auditory nerve) resulting in a bilateral sensorineural hearing loss
neurofibromatosis II (NF2)
transient otoacoustic emission and distortion product otoacoustic emissions occur in 98% of the normal-hearing population...therefore an absence of these emissions is consistent with abnormal hearing....when looking at and interpretating the results of TEOAEs and DPOAEs what are you looking for to figure out if there are any emissions during tests?
TEOAEs are present if...the reproducibility score is > 70% and if there are at least 3 signal/noise-ratio level frequency bands > 6 dB
DPOAEs are present if...there are at least 3 signal/noise-ratio level frequency bands > 6 dB
determine the disorder from the following:
audiogram: generally flat mild to moderately severe mixed hearing loss with poor low frequencies; carhart notch at 2000 Hz
tympanogram: Type As
acoustic reflexes: none
client: 30 years old
otosclerosis