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vowel sounds
periodic longer in duration than consonant sounds lower in frequency than most consonants
consonant sounds
periodic/aperiodic very short in duration higher in frequency than most vowels
middle ear
the air-filled space located in the temporal bone containin the three small middle-ear bones, incus, malleus, and stapes
eustachian tube
a stirrup-shaped bone within the middle ear that attaches to the round window of the inner ear vibrates and is transmitted through cochlear fluids within the organ of corti
outer ear function
-resonance and sound funneling -sound localization -protection for outer and middle ear -covered in cerumin (wax) and hair
cochlea
the snail-shaped part of the inner ear containing the sensory organs for hearing
ossicles
the three small bones (incus, malleus, stapes) that form the ossicular chain in the middle ear
oval window
a membrane-covered opening of the vestibule of the cochlea that is attached to the footplate of the stapes, vibration of the stapes footplate sets the oval window in vibration provides amplification because of the vibration!
pinna
the visible outer ear, also known as the auricle compromised of cartilage and skin
inner ear components
1) vestibule 2) semicircular canals 3) cochlea
inner ear
where hearing (and balance) begins!!
middle ear purpose
over come the difference in impedance between air and the fluid-filled head achieved by: air difference and lever action protects from loud sounds achieved by the two smallest muscles in the human body: tensor tampani and stapedius
impedance
opposition to the flow of energy
impedance of fluid is greater than...
the impedance of air
maleus
a hammer-shaped bone attached to the tympanic membrane within the inner ear creates leverage within the incus!
leverage
produced between the malleus and the incus malleus is longer than the incus and the difference in length creates leverage (less energy is needed to move the incus and hence the stapes)
scala media
(aka Cochlear Duct) contains the organ of hearing located in the inner ear
concha
located in the outer ear... helps provide resonance (amplification) to incoming sound
tympanic membrane
thin, translucent barrier between ear canal and middle ear space vibrates in response to sound air pressure must be equal on both sides of the TM for it to vibrate properly in response to sound
modiolus
the center of the bony spiral structure of the cochlea
incus
an anvil-shaped bone found in the middle ear helps with leverage along with the malus
scala vestibuli
connects to the oval window located in the inner ear
round window
an opening in the vestibule of the cochlea beneath the oval window on the cochlea, permitting the displacement of movement of fluid within the cochlea
organ of corti
area within the cochlea containing the tectoral membrane and hair cells transduces vibrations in fluid produced by sound into neural impulses
travelling wave
vibration along the basilar membrane - vibrating stapes footplate produces a wave in fluid-filled cochlea - distance wave travels from the stapes varies with sound frequency tonotopic organization is accomplished because of the travelling wave
dynamic range
an effect of the cochlear amplifier and allows us to perceive lower amplitude sounds then we could with no amplifier
semicircular canals
located in the inner ear
basiliar membrane
a thin tissue layer found within the cochlea on which the organ of corti rests said to be frequency selective or have tonotopic organization
basiliar membrane function
forier analysis: complex sounds are decomposed into their component frequencies (pure tones) How? combination of stiffness gradient and mass gradient
stereocillia
site of mechano-transduction i.e., the translation of the sound vibration into a nervous message which the brain can interpret
inner hair cells
one row responsible for producing our sensation of hearing loss or damage results in severe to profound hearing loss
cochlear amplifier
a positive feedback mechanism: it is stimulated by the motion of the BM, which in turn causes it to add to the motion of the BM
effects of the cochlear amplifier
1) widens our dynamic range 2) sharpens frequency selectivity 3) produces otoacoustic emissions
otoacoustic emissions
sounds produced by the inner ear- used to clinically determine cochlear health
scala tympani
connects to the round window in the inner ear
outer hair cells
three rows of approx. 12000 contain stereocillia and ion channels just like inner hair cells, BUT do NOT send information to the auditory nerve! -do not produce sensation of hearing -do not cause severe hearing loss or deafness if lost or damaged
outer hair cells "special" property
they can move!! depolarized (more +)=shorten hyperpolarized (more -)=lengthen
tonotopic organization
cochlea maps sound frequency to place of sensory activity in the inner ear (basilar membrane function) tono- frequency topic- place accomplished through the travelling wave
conductive hearing loss
indicates problem with sound transmission through the outer and/or middle ear -if BC thresholds are in the normal range but the AC thresholds are elevated
sensorineural hearing loss
indicates problem with the inner ear and/or auditory nerve -if there is no difference between AC and BC thresholds but both are elevated relative to norrmal
mixed hearing loss
hearing loss has both conductive and sensorineural components -if there is a difference between AC and BC thresholds and BC thresholds are elevated relative to normal
cone of light
the reflection from the otoscope's light
audiometer
electronic device used to present pure-tone sound waves of specified frequency of level to the patient
speech reception threshold (SRT)
component of speech audiometry what is the lowest level at which speech can be recognized 50% of thte time? values should correspond well to AC thresholds
pure tone audiometry
- detection of presence of hearing loss - determination of type of loss - determination of degree of loss - determination of configuration of loss
speech audiometry
completed using air conduction, almost never with bone conduction.... 2 components: 1) speech reception threshold (SRT) 2) speech-understanding score or word recognition score (WRS)
immittance
a term describing the flow of energy through a system
acoustic immittance testing
looking for auditory system function not hearing
air conduction (AC)
sound travels through the outer and middle ears before entering the cochlea
audiogram
a graphic representation of the results of a hearing test with axes for hearing level and frequency
word recognition score (WRS)
helps to decide if a hearing aid will help a patient dependent upon what happens if speech is brought above threshold levels and in noisy situations...speech recognition?
otoscopy
visual inspection of the outer ear and TM
otoscope
an instrument with a magnifying lens and a light designed to be inserted into the ear canal for the purposes of visual inspection
bone conduction (BC)
tests sensitivity of the inner ear and beyond to sound, bypassing transmission through the outer and middle ear performed with the bone conduction vibrator
tympanometry
measurement of middle ear mobility
(S)TORCH
acronym for syphillis, toxoplasmosis, other, rubella, cytomegalovirus, and herpes simplex infections
microtia
deformed pinna
stenosis
narrowing of the canal
atresia
absence of an ear canal
transducer
an electrical device that presents sound stimuli to the patient
tympanogram
provide information about the peak pressure and the static (peak) admittance of the middle ear system
threshold
the level at which an auditory signal can be detected 50% of the time
normal hearing
thresholds at or below 15 dB at all test frequencies
otitis media
middle ear infection more common in children than adults may occur with or without fluid build-up behind eardrum (effusion)
electrophysiological tests
test for infants stimulate the auditory system and record the electrical or mechanical response of a specific region
advantages to electrophysiological tests for infants
- no behavioral response is required - can isolate teh response of specific regions of the audiotory system
disadvantages to electrophysiological tests for infants
- not tests of hearing! - only gives info about isolated areas of the auditory system rather than providing info about the auditory system as a whole
genetic hearing loss
hearing loss due to genetic factors HL is rarely genetic...
behavioral observation audiometry (BOA)
-used primarily for neonates -child's behavioral response is to auditory stimuli may include: -changes in sucking or respiration rate, or eye widening - typically can only identify infants with severe or profound hearing losses
visual reinforcement audiometry (VRA)
-used for children 5 months to 2 years of age - tests speech, pure tones, or noise stimuli
conditioned play audiometry (CPA)
asses hearing acuity using conditioned responses to sound by engaging in play-oriented activities
congenital hearing loss
- present at birth but no genetic examples: fetal alcohol syndrome, STORCH infections, etc.
acquired hearing loss
normal hearing at birth with HL acquired sometimes afterwards
otosclerosis
abnormal growth of bone of the middle ear- stapes becomes fixated in oval window (spongy bony growth) -hereditary (60% family history) - hearing loss onset (15-45 yrs of age; starts usually at 20) -affects both ears (80% of patients) -affects women 2:1 -worsens rapidly during pregnancy
menieres disease
cochlear pathology: endolymphatic hydrops dizziness fluctuating hearing loss poor word recognition
presbyacusis
cochlear pathology: happens with aging
ototoxicity
cochlear pathology: 'mycin, 'platin (medications)
acoustic neuroma
a nonmalignant tumor in the left internal auditory canal -impact on reflexes -impact on speech understanding
what hearing device?
depends on many factors, but severity of hearing loss is the primary one
hearing aids best for...
mild to severe HL
cochlear implants best for
severe to profound HL
sensorineural hearing loss
the cochlea is damaged
hearing aids
attempt to compensate for the hearing loss by amplifying sound in frequency regions that correspond to the region of hearing loss
acoustic reflexes
triggered in response to loud sound reflex causes the muscles of the middle ear to contract bilaterally, thereby stiffening the middle ear system and increasing impedance
hearing aid frequency response
a measure of the response gain of a hearing aid across frequencies when presented at a constant input level
peripheral components of the auditory system
conduction of sound: -outer ear -middle ear sensory transduction and neural transmission -inner ear -auditory nerve
central components
brain stem & brain

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