Hearing Tests Flashcards
what test is done to assess hearing loss?
pure tone audiometry (PTA)
how is pure tone audiometry carried out?
soundproof room
transducer presents sound can be headphones/insert earphones or a bone conductor
patient presses a button when they have heard sound
define masking
narrow band noise centred around the test frequency is introduced into the non-test ear which distracts this ear
why is masking done?
to isolate the test ear
ensure true thresholds are obtained
what pitch are vowels?
low pitch (left side of the audiogram)
what pitch are consonants
high (right side of the audiogram)
mild hearing loss
20-40
speech (often noticed by partners first)
moderate hearing loss
40-70
severe hearing loss
70-90
profound hearing loss
90-120
three types of hearing loss
sensorineural
conductive
mixed
presentation of sensorineural hearing loss
no significant gap between air and bone conduction thresholds
what is the cause of a permanent SNHL?
damage to hair cells in cochlea or hearing nerve (or both)
is damage to the cochlea a natural part of the ageing process?
yes (presbycusis)
causes of SNHL
presbycusis noise exposure ototoxic drugs e.g. gentamicin certain infectious diseases e.g. rubella complications at birth benign tumour genetic predisposition
what does SNHL find difficult/
understanding speech
is SNHL reversible?
no
conductive hearing loss on an audiogram
significant gap between air and bone conduction thresholds where bone conduction thresholds are within normal limits
define conductive hearing loss
sound is not able to pass freely into the inner ear, usually an abnormality of the outer or middle ear
causes of CHL
glue ear
perforated ear drum
mixed hearing loss presentation on audiogram
significant gap between air and bone conduction levels, but bone conduction is not within normal limits
what does a mixed hearing loss tell you?
there is damage to both outer or middle and inner ear
causes of mixed hearing loss
genetic factors birth defects diseases infections tumours/masses head injuries
otosclerosis presentation on PTA
Cahart’s notch at 2kHz
define tympanometry
this is a test used to assess the condition of the middle ear by creating vibrations of pressure in the ear canal
what does tympanometry permit
distinction between SNHL and CHL
OME (showing presence of middle ear fluid- flat)
tympanic membrane perforation showing a large ear canal volume
