SHS 221 Module 6D

The type, degree, configuration, symmetry, and stability of hearing loss

What is an audiogram used to determine?

Air conduction

What does AC stand for?

Bone conduction

What does BC stand for?

The entire auditory pathway

What does air conduction testing assess?

It directly stimulates the inner ear, bypassing the outer and middle ear

What does bone conduction testing assess?

Air-bone gap (ABG)

The difference between air conduction and bone conduction thresholds at a given frequency

It can reveal conductive hearing loss that might otherwise be missed, especially in children

Why is bone conduction testing important even when air conduction thresholds are normal?

AC and BC thresholds are within normal limits, and the ABG is 10 dB HL or less

What are the characteristics of normal hearing on an audiogram?

AC thresholds are poorer than BC thresholds, with an elevated ABG of approximately 10 dB or more

What is the typical pattern of conductive hearing loss?

The outer and/or middle ear

What part of the auditory system is associated with conductive hearing loss?

Both AC and BC thresholds are elevated, with an ABG of 10 dB or less

What is the typical pattern of sensorineural (sensory neural) hearing loss?

The cochlea

What part of the auditory system is associated with sensorineural hearing loss?

Both AC and BC thresholds are elevated, and there is an elevated ABG of approximately 10 dB or more

What is the typical pattern of mixed hearing loss?

The middle ear, inner ear, and auditory nerve

What areas are associated with mixed hearing loss?

AC and BC thresholds are often within normal limits, with an ABG of 10 dB or less

What is the typical audiogram pattern for central hearing loss?

The auditory brainstem or cortex

What areas are associated with central hearing loss?

No organic pathology and poor test-retest reliability

What is functional hearing loss associated with?

How much hearing sensitivity has decreased

What does the degree of hearing loss describe?

By calculating the average of thresholds at 500, 1000, and 2000 Hz (the three-frequency average)

How can the degree of hearing loss be calculated?

(10 + 10 + 10) / 3 = 10 dB HL

If thresholds are 10, 10, and 10 dB HL at 500, 1000, and 2000 Hz, what is the average?

Normal

Hearing loss severity: less than 15 dB HL

Slight

Hearing loss severity: 16-25 dB HL

Mild

Hearing loss severity: 26-40 dB HL

Moderate

Hearing loss severity: 41-55 dB HL

Moderately severe

Hearing loss severity: 56-70 dB HL

Severe

Hearing loss severity: 71-90 dB HL

Flat audiogram configuration

Hearing thresholds remain relatively similar across frequencies

Gradually sloping configuration

Thresholds progressively worsen as frequency increases, with a gradual slope

Steeply sloping configuration

Thresholds worsen rapidly as frequency increases

Precipitously sloping configuration

Thresholds worsen very sharply over a range of frequencies

Rising configuration

Thresholds improve as frequency increases

Peaked or saucer configuration

Thresholds are poorer at lower and higher frequencies but better in the middle frequencies

Trough configuration

Hearing loss of 20 dB or greater in the mid frequencies (1000-2000 Hz), but not at the extreme frequencies (500 or 4000 Hz)

Notch configuration

Hearing loss of 20 dB or greater at one frequency, with complete or near-complete recovery at adjacent octave frequencies

Symmetry when interpreting an audiogram

How similar or different hearing thresholds and configurations are between the two ears

Hearing loss in both ears

What is bilateral hearing loss?

Hearing is normal in one ear, but hearing loss is present in the other ear

What is unilateral hearing loss?

The degree or configuration of hearing loss differs between the ears

What does asymmetric hearing loss mean?

Stable hearing loss

Hearing thresholds show no significant change over time; less than a 10 dB change

Hearing loss that becomes worse over time

What is progressive hearing loss?

Sudden hearing loss

Hearing loss that occurs suddenly and requires immediate medical attention to determine its cause and treatment

Fluctuating hearing loss

Hearing loss that changes over time, sometimes improving and sometimes worsening

Normal hearing

AC thresholds: normal

BC thresholds: normal

Air-bone gap: ≤ 10 dB

Conductive hearing loss

AC thresholds: elevated

BC thresholds: normal

Air-bone gap: ≥ 10 dB

Sensorineural hearing loss

AC thresholds: elevated

BC thresholds: elevated

Air-bone gap: ≤ 10 dB

Mixed hearing loss

AC thresholds: elevated

BC thresholds: elevated

Air-bone gap: ≥ 10 dB

Central hearing loss

AC thresholds: often normal

BC thresholds: often normal

Air-bone gap: ≤ 10 dB