Lecture 10 Navigating the Audiogram Part II

Degree of hearing loss is determined by

air conduction thresholds

Note: Remember – air conduction tells us configuration. Does not matter if bone conduction thresholds are symmetrical or asymmetrical for the purpose of configuration

Normal (Degree of Hearing Loss)

-10 to 15

Slight (Degree of Hearing Loss)

16 to 25

Mild (Degree of Hearing Loss)

26 to 40

Moderate (Degree of Hearing Loss)

41 to 55

Moderately Severe (Degree of Hearing Loss)

56 to 70

Severe (Degree of Hearing Loss)

71 to 90

Profound (Degree of Hearing Loss)

91 and above

Configuration

the shape of hearing thresholds on the

audiogram

symmetrical or asymmetrical

Relationship between ears is described

Symmetrical hearing loss

thresholds of right and left ear are within 10 dB HL or less of each other

Asymmetrical hearing loss

thresholds of right and left ear have greater than 10dB HL gap between them

Type of hearing loss

first evaluate the relationship between bone conduction and air conduction

To hear a sound via air conduction

the sound must travel through the entire auditory system. Sound starts at the opening of ear canal and travels through all components until it reaches the auditory cortex

To hear a sound via bone conduction

the sound energy starts with vibrations in the skull. The vibrations stimulate the fluid (endolymph and perilymph) and hair cells in the cochlea. Sound then travels the auditory pathway as normal to auditory cortex

TL; DR

Air conduction the normal route of hearing. Bone conduction takes a “shortcut” and starts at the cochlea

Sensorineural Hearing Loss

Characterized by air and bone

conduction thresholds that

are equally abnormal

No air–bone gaps (AC and BC

within 10 dB HL of each other)

Conductive Hearing Loss

Characterized by air responses

abnormal and bone within normal

Presence of air–bone gap

(difference between AC and BC

greater than 10 dB HL)

Mixed Hearing Loss

Combination with both conductive and sensorineural components

• Bone conduction is abnormal and air conduction is more abnormal

• Air–bone gaps present

Cross Checking

an important tool to estimate the reliability of an evaluation

• Pure-tone average (PTA) and SRT should be around 10-15 dB HL or less of each other

• If disagreement occurs between tests be sure to document on audiogram.

• Reliability is typically categized as Excellent, Good, Fair, Poor, and sometimes Questionable

If Disagreement Occurs

1. Reinstruct patient

2. Make sure equipment is placed on patient correctly and working

3. Make sure test is being administered appropriately

4. Mark reliability appropriately (Fair, Poor, or Questionable)

5. Document, document, document!

Counseling Patient

Showing a regular audiogram to a patient

doesn’t tell them much.

• Using an audiogram with the speech banana or familiar sounds can be meaningful