I recall my days in clinical medicine during our HEENT block and how I struggled to determine whether or not a patient has a conductive hearing loss (problem originates from the external (e.g. cerumen impaction), middle ear or tympanic membrane) vs. sensorineural hearing loss (problem originates from the inner ear, cranial nerve VIII, or the cochlear nucleus in the brainstem).
As part of our routine new patient evaluation, we always perform a bedside screening test for hearing loss aka Weber and Rinne tests.
Tools required: a 512-Hz tuning fork
How to perform a Weber test (localization): strike the tuning fork on your elbow (olecranon) and place on the top of the patient’s head. (*Note: Avoid striking the fork on a chair/exam bed as it may produce an overtone and lead to inaccurate measures)
- Interpretation: If the patient reports that hearing sound is equal in both ears, it is a NORMAL result. If the patient reports the sound appears louder in one ear than the other, this indicates a conductive hearing loss (CHL) in the affected ear, or sensorineural hearing loss (SNHL) in the unaffected ear.
The next step to determine if there is a conductive hearing loss would be to proceed with a Rinne test . . .
How to perform a Rinne test (conduction): strike the tuning fork and place on the patient’s mastoid process (1) and compare that sound to that of when the tuning fork is placed in front of the patient’s ear (2). I’ll typically just ask the patient, “Is 1 louder or 2?”
- Interpretation: Sound is typically louder when the tuning fork is placed in front of the patient’s ear because air-conduction is greater than bone-conduction (AC > BC).
Hearing Tests Interpretation Summary:
- Normal hearing: Midline (Weber); AC > BC (Rinne)
- Sensorineural hearing loss: Normal ear (Weber); AC > BC (Rinne)
- Conductive hearing loss: Affected ear (Weber); BC > AC (Rinne)
Medical History Trivia: Bone conduction was discovered in the 16th century. Ernst Heinrich Weber and his brother, Wihelm, developed the early tuning fork tests based on a study on transmission of sound and airwaves back in 1825. Weber noted that when a tuning fork was placed at the skull of a deaf person, sound is better heard in the impaired ear than in the good ear.