How to distinguish between Sensorineural Hearing Loss (SNHL) and Conductive Hearing Loss (CHL) using Rinne and Weber tests?

Distinguishing Between Sensorineural and Conductive Hearing Loss Using Rinne and Weber Tests

The Weber and Rinne tuning fork tests are essential diagnostic tools that effectively differentiate between sensorineural hearing loss (SNHL) and conductive hearing loss (CHL), with distinct patterns of results for each condition. 1

Proper Testing Technique

Weber Test

• Vibrate a 256 or 512 Hz tuning fork by striking it on your covered elbow or knee (not on hard surfaces) 1, 2
• Place the vibrating tuning fork at the midline of the forehead or on maxillary teeth (not false teeth) 1
• Ask the patient where the sound is heard; normally it should be heard at midline or "everywhere" 1, 2
• If sound lateralizes to one ear: 1
  • Either there is CHL in that ear
  • Or there is SNHL in the opposite ear

Rinne Test

• Vibrate a 256 or 512 Hz tuning fork by striking it on your covered elbow or knee 1, 2
• Place the vibrating tuning fork over the mastoid bone of one ear, then move it to the entrance of the ear canal (not touching the ear) with the tines directed toward the ear 1
• Ask if the sound is louder behind the ear (bone conduction) or in front of the ear (air conduction) 1, 2
• Normally, air conduction should be better than bone conduction (positive Rinne) 2
• If bone conduction is better than air conduction (negative Rinne), there is CHL in that ear 1
• Repeat for the other ear 1

Interpretation of Results

Conductive Hearing Loss (CHL)

• Weber test: Sound lateralizes to the affected ear 1, 2
• Rinne test: Negative result (bone conduction > air conduction) in the affected ear 1
• Otoscopic examination often shows abnormalities (cerumen impaction, middle ear fluid, perforated tympanic membrane, etc.) 1

Sensorineural Hearing Loss (SNHL)

• Weber test: Sound lateralizes to the unaffected ear 1, 2
• Rinne test: Positive result (air conduction > bone conduction) in both ears 1, 2
• Otoscopic examination is typically normal 1

Clinical Pearls

• Combining both Weber and Rinne tests significantly improves diagnostic accuracy compared to using either test alone 1, 3
• The sensitivity of tuning fork tests is approximately 77-85% and specificity 85-94% when compared to audiometry 4, 3
• Tuning fork tests are less reliable for mild conductive hearing loss with air-bone gaps of 5-35 dB 5
• A smartphone vibration application may serve as an alternative to a tuning fork for the Weber test with comparable sensitivity and specificity 4
• The "hum test" can substitute for the Weber test with similar accuracy—if the patient hears their own hum louder in the affected ear, it suggests CHL in that ear 1

Common Pitfalls to Avoid

• Failing to strike the tuning fork correctly can produce nonharmonic frequencies that affect test accuracy 1
• Testing should be performed in a quiet environment to minimize ambient noise interference 2
• Impacted cerumen must be removed prior to establishing a diagnosis, as it can cause CHL 1
• Misdiagnosis of SNHL as CHL can lead to delays in appropriate treatment 1, 2
• While tuning fork tests provide valuable initial information, they do not replace formal audiometric testing 1, 6

Diagnostic Algorithm

1. Perform otoscopic examination to rule out obvious causes of CHL 1
2. Conduct Weber test to determine if sound lateralizes 1
3. Perform Rinne test on each ear 1
4. Interpret combined results: 3
   • CHL: Weber lateralizes to affected ear + negative Rinne in affected ear
   • SNHL: Weber lateralizes to unaffected ear + positive Rinne in both ears
5. Refer for formal audiometry to confirm diagnosis 1, 6