Audiogram Curve description Horizontal axis Frequency Audiogram Curve description Vertical axisHearing leveldB Output transducers Ear phones Bone vibrator calibration Used to define audiometric zero ID: 914986
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Slide1
PURE TONE AUDIOGRAM
ascertains the hearing acuity (hearing threshold level) of a subject for pure tone sounds of various frequencies.
Slide2Slide3Audiogram Curve description
Horizontal axis: Frequency
Slide4Audiogram Curve description
Vertical
axis:Hearing
level(dB)
Slide5Output transducers
Ear phones
Bone vibrator
Slide6calibration
Used to define audiometric zero
Electronic
caliberation
-at least once in 6 monthsBiological caliberation-daily
drtbalu's otolaryngology online
Slide7Noiseless test environment
Slide8Slide9Procedure
Method (
Carhart
Jerger
modified Hughson –Westlake procedure)
;5 up 10 down method
Decreased
by 10 dB,
Increased
by 5 dB
AC
: 1000 – 8000 Hz, 500, 250
BC
: 1000 – 4000 Hz., 500, 250
Tones presented
for
1-3 seconds, with
intervals
of 1-3 seconds
Slide10Slide11Lower frequency AB gap-occlusion effect
Higher frequency AB gap-Collapse of EAC
Slide120 to 25 db – Normal hearing
26 to 40 db – Mild deafness
41 to 55 db – Moderate deafness
56 to 70 db – Severe deafness71 to 90 db – Very severe deafness
Above 90 db – Profound deafness
Slide13Pure tone Audiometry -
Uni
lateral /
Bi
lateral
Clinical Severity
Mild
Moderate
Severe
Profound
Types
Conductive
Sensorneural
Mixed
Slide14Pure Tone Audiometry -Interpretation
Normal - Both AC / BC thresholds - < 20 dB
Conductive - AC abnormal / BC normal
Conductive-BC<20dB, AB gap>20 dB
Slide15Sensorineural
&
mixed hearing loss
Sensorineural
-
AB gap < 20 dB, BC>20dB
Mixed
- AB gap >
20 dB BC>20dB
Slide16Stiffness more—left sloping, more loss in lower frequencies
mass more-Right sloping, more loss in higher frequencies
Slide17Ossicular
discontinuity
Slide18Slide19Flat audiogram suggests an atrophy of
stria
vasscularis
Strial
presbyacusis,salicylate
poisoning, other
strial
lesion
Slide20Slide21Slide22Slide23Slide24Slide25Slide26Slide27