Audiogram InterpretationOzarks Technical Community College

Hearing Loss is defined by…Degree/Magnitude of Loss

Normal, slight, mild, moderate, moderately-severe, severe, profound

Type of LossConductiveSensorineural Mixed

Configuration of LossFlat, rising, sloping, precipitous

Normal HearingNormal AC and

BC thresholds (≤15 dB)

Many different scales exist regarding degree of hearing loss

For the purposes of this class, we will use the scale on the next slide.

Degree of Hearing LossThis is the exact scale that I

use in interpreting audiogramsSome clinics are more

liberal and consider normal hearing to be any threshold up to 25 dBHL

In determining the degree of loss, the textbook approach would be to calculate the puretone average (PTA=average dB of AC thresholds at .5, 1, 2 kHz) and compare the PTA to the scale at right. From: Northern, J. Hearing Disorders

(3rd ed)

Audiometric InterpretationIf a patient has a disorder of the outer and/or

middle ear ONLY, then AC thresholds will be abnormal in the presence of normal BC thresholds

Air-bone gap = greater than or equal to 15dB difference between AC and BC

This is called a conductive hearing loss (CHL), as sound cannot properly conduct through the outer and/or middle ear to reach the normal-hearing cochlea

Some Causes of CHLAnotiaMicrotiaAtresiaOuter ear infectionMiddle ear infectionOtosclerosisDislocation of the middle ear bonesCholesteatomaEar wax!

Conductive Hearing LossNormal BC

thresholdsAbnormal AC

thresholdsAn air-bone gap is

present at .5, 1, 2, and 4 kHz

WRS should be nearly normal, as there is no damage to the cochlea/nerve

Image from: telemedicine.orbis.org

This patient has a mild CHL

Collapsing CanalsIf you ever discover a conductive hearing loss

component in the high frequencies when you are using traditional headphones, it is necessary to retest your air-conduction thresholds using inserts.

The pressure of traditional headphones can actually cause a collapse of the ear canal in some patients (especially true in the elderly)

Audiometric InterpretationIf a patient has a disorder of the inner ear

and/or auditory nerve, then AC thresholds will be equal to BC thresholds (no air-bone gap) and both will be abnormal

This is called a sensorineural hearing loss (SNHL)

Some Causes of SNHLAging (presbycusis)Noise ExposureGeneticsAcoustic NeuromaMeniere’s DiseaseOtotoxic Drugs

Sensorineural Hearing LossAbnormal AC and BC

thresholdsNo air-bone gapWRS will vary depending

on degree of loss and cochlear vs. neural damage

According to the PTA method of determining degree of HL, this patient has a slight SNHL.

However, due to the sloping configuration, it is more accurate to define the loss as a slight-sloping-to-severe SNHL.

Image from: telemedicine.orbis.org

Puretone Audiometry InterpretationIf a patient has a disorder of the inner ear

and/or auditory nerve AND an outer/middle ear disorder, then both AC thresholds and BC thresholds will be abnormal AND an air-bone gap will exist

This is called a mixed hearing loss (MHL)Example: 75 yo, male with age-related

hearing loss and bilateral otitis media

Mixed Hearing LossAbnormal AC and BC

thresholdsAir-bone gap presentExpected WRS based

on BC thresholdsThis patient has a

mild to moderately-severe MHL.

Image from: telemedicine.orbis.org

Configuration of HLFlat

Thresholds within 20dB of each other across all frequencies

RisingLow frequency thresholds are at least 20dB poorer

than high frequenciesSloping

High frequency thresholds are at least 20dB poorer than low frequencies

PrecipitousHigh frequency thresholds worsen by at least 20dB

per octave

Always keep these FDA Regulations in mind…If any of the following conditions exist, a patient must be

referred for a medical evaluation by a physician (preferably an ENT):Visible congenital or traumatic deformity of the ear.History of active drainage from the ear in the previous 90

days.History of sudden or rapidly progressive hearing loss

within the previous 90 days.Acute or chronic dizziness.Unilateral hearing loss of sudden or recent onset within

the previous 90 days.Audiometric air-bone gap equal to or greater than 15

decibels at 500 Hz, 1,000 Hz, and 2,000 Hz.Visible evidence of significant cerumen accumulation or a

foreign body in the ear canal.Pain or discomfort in the ear.