11/13/24, 7\:31 PM Guide | Audiogram interpretation

Audiogram interpretation

Table of contents

What is an audiogram?

An audiogram is a hearing test conducted under ideal listening conditions in a soundproof booth.
The test includes di
audiogram helps distinguish conductive loss (outer/middle ear) from sensorineural loss (cochlea/cochlear nerve).
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As well as di
identifying the underlying cause of the hearing loss.

Interpreting an audiogram

A standard audiogram ranges from -10 decibels at the top of the y-axis to 120dB at the bottom of the y-axis (from very quiet to
very loud). The x-axis ranges from 125 Hz to 8000 Hz (low pitch to high pitch).
Audiograms use di
air and bone conduction.
Figure 1. A blank audiogram. [2]
X-axis\: frequency in Hertz (pitch)
Y-axis\: hearing levels in decibels (loudness)

Audiogram key

Air conduction
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O = Right ear unmasked
△ = Right ear masked
X = Left ear unmasked
▢ = Left ear masked
Bone conduction
\< = Right ear unmasked
[ = Right ear masked
> = Left ear unmasked
] = Left ear masked
Clinical masking in audiology refers to introducing noise to the non-test ear during a pure-tone audiogram. This aims to
ensure that the test ear hears the presented tone and is not 'cross-heard' by the non-test ear.
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Hearing thresholds

Normal hearing\: can hear quiet sounds of less than 20dB
Mild hearing loss\: hearing loss between 20 – 40dB
Moderate hearing loss\: hearing loss between 41 – 70dB
Severe hearing loss\: hearing loss between 71 – 95dB
Profound hearing loss\: hearing loss over 95dB
Air-bone gap
An air-bone gap (ABG) is de
thresholds.
ABGs are found in patients with conductive (CHL) or mixed (MHL) hearing loss generally attributed to outer- and/or
middle-ear diseases such as otitis externa, tympanic membrane perforation, interruption or
and chronic suppurative otitis media.
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Typically an air-bone gap is considered if there is a di
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Examples of common audiograms

Normal audiogram (above 20dB in all frequencies)

Figure 2. Normal audiogram

Sensorineural hearing loss (right ear)\: no air-bone gap present

Sensorineural hearing loss refers to hearing loss due to damage to the structures of the inner ear (cochlea) or cochlear nerve.
Figure 3. Sensorineural hearing loss
Common causes of sensorineural hearing loss include\:
Sudden sensorineural hearing loss (SSHL)\: the underlying aetiology remains unclear but is thought to relate to possible
vascular, viral, in
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Noise-induced hearing loss
Presbyacusis
Vestibular schwannoma

Conductive hearing loss (right ear)\: air-bone gap present

Conductive hearing loss refers to hearing loss due to impaired sound transmission through the outer and middle ear.
Figure 4. Conductive hearing loss
Common causes of conductive hearing loss include\:
Any obstruction to the ear canal (e.g. wax, foreign body, furuncle, oedema)
Perforation of tympanic membrane
Fluid in the middle ear (e.g. glue ear, otitis media)
Any disruption of ossicles (e.g. trauma)

The pathophysiology of age-related hearing loss (ARHL), or presbycusis, involves a complex interplay between environmental
and genetic factors. 6
These include noise exposure, genetic predisposition, cell damage and neural degeneration.
Presbycusis is characterised by bilateral hearing loss above 2000Hz. On a standard audiogram, presbycusis appears as an
overall down-sloping line representing impaired hearing at higher frequency sounds.
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Presbyacusis is classically bilateral and symmetrical.
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Figure 5. Presbyacusis

Noise-induced hearing loss (sensorineural hearing loss with a notch at 4000 Hz)

Noise-induced hearing loss is typically characterised by a notch on the audiogram at 4000 Hz.
Figure 6. Noise-induced hearing loss

Meniere’s disease (right ear)

Meniere's disease is typically characterised by low-frequency sensorineural hearing loss.
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Figure 7. Meniere’s disease
Meniere's disease
Meniere’s disease presents a triad of vertigo, tinnitus and hearing loss.

Otosclerosis (right ear)

Otosclerosis is pathologically characterised by abnormal bony remodelling, which includes bone resorption, new bone
deposition, and vascular proliferation in the temporal bone.
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Otosclerosis is characterised by conductive hearing loss with loss in bone conduction at 2000 Hz (referred to as Carhart’s
notch).
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