audiology midterm

outer ear

generates acoustic energy

middle ear

generates mechanical energy; inner layers of tympanic membrane

inner ear

generates fluid energy; consists of auditory and vestibular labyrinths

auricle (aka pinna)

external outer ear

external auditory meatus

ear canal

tympanic membrane

ear drum

middle ear cavity

filled with air

ossicles

ear bones; the smallest bones in the human body

malleus (hammer)

lateral-most bone of the chain; connected to the eardrum

incus (anvil)

center bone of the chain

stapes (stirrup)

medial-most bone, rocks in and out of the oval window

eustachian tube (auditory tube)

primary function- equalizes air pressure between the middle ear (ME) cavity and nasopharynx; secondary function- helps to drain fluid which might accumulate in ME into nasopharynx

stapedius and tensor tympani

holds bone in position

auditory labyrinth

cochlea, sensory end organ of hearing

vestibular labyrinth

semicircular canals, the sensory end organ of balance

Organ of Corti

contains sensory cells of hearing (outer and inner hair cells)

outer hair cells

tuned to sound intensity; three rows of cilia embedded into tectorial membrane; about 13,000 all together; 10% are neurologically connected to the brain via nerve fibers

inner hair cells

tuned to sound clarity; one row of cilia in proximity to tectorial membrane; about 3,500 all together, 90% are neurologically connected to the brain via nerve fibers

retrocochlear pathway

starts with the auditory nerve and travels up toward the brain via neural fibers through several other structures; most fibers are afferent but few are efferent

sound

a physical phenomenon which describes a movement of vibration of an elastic medium without permanent displacement of the particles

medium of transmission, source of energy, vibrating object which generates audible pressure wave

three prerequisites of sound

frequency (f)

a number of complete vibratory cycles per unit of time

amplitude (A)

a derived unit of measurement describing an object's distance from rest to maximal displacement

period (p)

amount of time needed to complete one cycle of vibration

phase

describes the relative timing of compressions and refraction of waves (how cycles relate to each other)

sound pressure level (dB SPL)

actual measured pressure

hearing level (dB HL)

used to show the degree of a hearing impairment, as compared to the reference of "normal hearing"; audiogram

sensation level (dB SL)

how intensity in dB above the person's threshold

informal observation for hearing loss

look, play, listen

air conduction audiomentry

the normal means of sound transmission in day-to-day situations; results represent degree of hearing loss (not type); findings cannot localize site of damage

pure tone air conduction audiometry

determines the loudness or intensity threshold in dB at which a person just begins to hear sound for this normal mode of sound transmission

bone conduction audiometry

placed on the mastoid or the forehead; regardless of placement, the better cochlea will always respond first; gives TYPE of hearing loss

masking principles

keeps the non test ear busy while establishing results for the test ear; accomplished by presenting a noise stimulus to the non test ear; only performed when there is a greater than 40/60 dB (phones and inserts) between air conduction results between ears OR air conduction of one ear and unspecified bone conduction; DETERMINES HOW MUCH OF THE HEARING LOSS IS CONDUCTIVE AND HOW MUCH IS SENSORINEURAL WHEN BOTH OCCUR IN THE SAME EAR (MIXED HEARING LOSS)

interaural attenuation

the point to which sound becomes loud enough to "cross over" to the other ear

phone: 40dB

inserts: 60 dB

bone: 0 dB

behavioral observation audiometry (BOA)

used on child 6 to 7 months; responses are reflexive; unlikely to be the softest sounds a child is capable of hearing (does not determine thresholds, but can rule out hearing loss)

visual reinforcement audiometry (VRA)

used on child of 6-24 months; based on a child's natural instinct to turn searchingly for an interesting sound when it is heard; the child will continue to do this when rewarded with an appealing visual stimulus

conditioned play audiometry (CPA)

used on child of 2.5-5 years; makes pure tone audiometry into a game in sound field or using transducer

normal hearing loss degree

-10 to 15 dB

concept of "incidental learning"

slight hearing loss degree

16 to 25 dB

intervention includes: FM systems/amplification and classroom accommodations

mild hearing loss degree

26-40 dB; simulate the experience by closing off the tragus; can miss 25-40% of speech signal; intervention includes: FM system/amplification and classroom accommodations

moderate hearing loss degree

41-55 dB

can miss up to 80% of average level conversational speech (at 50 dBHL)

impact of noise on hearing is drastically increased

treatment includes: amplification (depending on the etiology)

moderately severe hearing loss degree

56-70 dB

miss about 100% of average conversational speech

timely intervention critical

treatment: amplification/ ancillary support services

severe hearing loss degree

71-90 dB

can miss 100% of all speech

early intervention for a child is a must

accessibility to sound with and without devices (hearing aids, cochlear implant, or both)

profound hearing loss degree

91+ dB

can miss 100% of all speech

early intervention for a child is a must

accessibility to sound with and without devices (hearing aids, cochlear implant, or both)

conductive hearing loss

characterized by abnormal air responses and normal bone responses; PRESENCE OF AIR BONE GAP; damage to outer and middle ear

sensorineural hearing loss

characterized by equally abnormal air and bone conduction; no air bone gap; damage to inner ear

mixed hearing loss

combination of sensorineural and conductive hearing loss; bone conduction is abnormal but air conduction is MORE abnormal; air bone gaps present

unilateral hearing loss

hearing loss in one ear

asymmetrical hearing loss

hearing loss in one ear is much better than in another; causes issues of localization of sound; possible sign of pathology

medical definition:

- difference of 10 dB at 3 or more consecutive frequencies

- difference of 15 dB at 2 or more consecutive frequencies

- difference of 20 dB at 1 or more consecutive frequencies

progressive hearing loss

hearing loss that degrades over time

speech recognition threshold (SRT)

how soft someone is able to recognize what is being said and repeat back, point to a picture, point to body part, ect.

- used a cross check and should correspond with the PTA (pure tone average)

- spondees: two-syllable words with equal stress on each syllable

- used to test difficult populations

word discrimination

how well a person can understand a given set of words

- presented at a louder level than their thresholds or SRT

- used a metric to compare ears and performance over time

- used for basic cochlear implant candidacy

most comfortable listening level (MCL)

can be used as a reference point on where to test WR

uncomfortable listening level (UCL)

level at which sound is no longer tolerable; used to determine dynamic range

dynamic range

the range of sound between when the sound becomes AUDIBLE and when the sound becomes UNCOMFORTABLE

otoscopy

used to examine the outer ear, auditory meatus (ear canal), and tympanic membrane

tympanometry

evaluates functional properties of the middle ear; provides information regarding the health of middle ear structures

results can be affected by:

- TM perforation

- occluding wax

- foreign bodies

- malformed or misshapen ear canals

characteristics of a tympanogram

pressure, compliance, ear canal volume

pressure

normal atm; provides information regarding the function of the Eustachian tube; represented on the x-axis; Eustachian tube should equalize to the pressure changes made through the tympanometer

compliance

measurement of mobility of TM; provides information regarding ossicular chain, tympanic membrane health, and ME pathology; represented on the y-axis

normal range of compliance for children

0.25 to 1.05

normal range of compliance for adults

0.3 to 1.7

ear canal volume (ECV)

a measurement of the physical volume of the ear canal; provides information regarding outer ear pathology, tympanic membrane perforation, and pressure equalization tube patency

normal range of ECV in children

0.3 mL to 1.0 mL

normal range of ECV in adults

0.65 mL to 1.75 mL

wax build up

low ECV indicates...

TM perforation

high ECV indicates...

Type A tympanogram

indicates normal TM movement and pressure; looks like a peak

Type AS tymp

indicates reduced movement of the TM/ ME dysfunction; most often is a sign of Eustachian tube dysfunction, allergies, recent OM that is recovering, ossicular chain fixation, or other ME issue; looks like a shallow peak

Type AD tymp

indicates excessive movement of the TM; most often a sign of ossicular discontinuity, thinning TM from frequent OM, or other ME dysfunction; looks like a large peak

Type C tymp

indicates excessive negative pressure; looks like a slanted peak

Type B tymp

FLUID/ flat line; indicates no movement of the TM; most often a sign of Otitis media (normal ECV), cholesteatoma (normal ECV usually), cerumen impaction (low ECV), or TM perforation (high ECV)

Otoacoustic Emissions (OAEs)

objective test of how the cells in the cochlea are functioning; completed by sending a signal into the ear and looking for an echo to return; usually look at 1000-8000 Hz; if OAE is present, we know there is no more than a MILD hearing loss; if OAE is absent, hearing loss likely present

electrophysiological measures

ABR and ASSR- objective tests, indirect measure of hearing sensitivity, auditory response (8th nerve and above) to an electric stimulation; measured through electrodes; screening or diagnostic

Auditory Brainstem Response (ABR)

check stimulus and tone burst

screening or diagnostic

quickly produces electrophysiological wave forms

gross measure across all frequencies (dB nHL vs. dB HL)

test of choice in NICU when OAE screening is failed

Auditory Steady State Response (ASSR)

frequency specific

diagnostic only

complete evaluation takes longer as each frequency is tested

can approximate configuration of hearing loss

differentiates between severe and profound hearing loss

electrostagmography (ENG) or videonystagmography (VNG)

tests the vestibular system; Nystagmus as function of proprioception

disorder

abnormality of the anatomical structures of the auditory system with or without a concomitant

impairment

loss of function of the auditory system

disability

restriction or lack of ability to perform an activity in the range that is considered normal

handicap

difficulty an individual perceives as a result of an impairment or a disability

handicap screening

paper screeners that determine how the person is coping with their disability

Speech Detection Threshold (SDT) or Speech Awareness Threshold

how soft a patient is aware/detect speech is occuring