Tuning Fork Tests: Weber and Rinne
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Direct answer
Tuning fork tests distinguish conductive from sensorineural hearing loss at the bedside using a 512 Hz fork. Rinne's test compares air conduction with bone conduction in each ear: it is positive when air conduction is heard longer, which is normal or sensorineural loss, and negative when bone conduction outlasts air conduction, indicating conductive loss. Weber's test lateralises to the ear with conductive loss and away from the ear with sensorineural loss.
What you must remember
- Choice of fork: 512 Hz is preferred; a 256 Hz fork produces vibratory sensation that misleads, and higher forks fade too quickly.
- Rinne's test: strike the fork on the elbow or knee, place the base on the mastoid, then beside the ear canal without touching; ask which is heard longer. Positive — air conduction greater than bone conduction (normal ear or sensorineural loss). Negative — bone conduction greater than air conduction (conductive loss).
- Weber's test: place the vibrating base on the vertex or midline of the forehead; a normal person hears it equally in both ears. Lateralisation to the diseased ear means conductive loss in that ear; lateralisation to the healthier ear means sensorineural loss on the opposite side.
- Absolute bone conduction: compares the patient's bone conduction with the examiner's by occluding the canal; it is reduced in sensorineural loss and normal in conductive loss.
- Rinne false negative: in a totally dead ear, bone conduction is heard by the opposite cochlea, so the test appears negative; the clue is that Weber lateralises to the opposite, better ear.
- Bedside sequence: interpret both ears together — for example, right Rinne negative with Weber to the right equals right conductive hearing loss.
- Confirmation: tuning forks screen; pure tone audiometry quantifies the loss and confirms the pattern.
Common confusion
The commonest error is saying Weber lateralises to the better ear in conductive loss. In fact the affected ear, deprived of ambient masking noise, localises the bone-conducted sound — Weber goes to the worse ear in conductive loss and to the better ear in sensorineural loss. Also, a negative Rinne appears only when the conductive component is significant, so mild conductive loss may still show a positive Rinne.
Exam-focused takeaway
In theory, prepare the full interpretation for unilateral and bilateral disease, including the false negative Rinne, with a simple line diagram. In viva, examiners hand you a fork and expect the technique, the frequency and instant interpretation of any combination; rehearse aloud until reflexive. In the posting, test every hearing loss patient before seeing the audiogram, then compare — the fastest way to trust your findings.
Frequently asked questions
Which frequency tuning fork is used and why?
512 Hz, because it is within the speech frequency range, produces minimal vibratory sensation and sustains vibration long enough for comparison.
What does a negative Rinne indicate?
Bone conduction heard longer than air conduction, indicating conductive hearing loss in that ear, typically from wax, perforation, otitis media or otosclerosis.
Where does Weber lateralise in sensorineural loss?
Away from the affected ear, towards the better ear, because the damaged cochlea responds less to bone-conducted sound.
What is a false negative Rinne?
In profound unilateral sensorineural (dead) ear, the bone-conducted stimulus crosses to the opposite cochlea, so the test wrongly suggests conductive loss; Weber lateralises to the opposite ear and exposes the error.
What is absolute bone conduction?
A comparison of the patient's bone conduction with the examiner's, with the canal occluded; it is diminished in sensorineural loss and normal in conductive loss.
What test quantifies these bedside findings?
Pure tone audiometry, which measures air and bone thresholds separately and confirms the type and degree of hearing loss.