How a tuning fork finds the cause of hearing loss
A tuning fork helps localise hearing loss by separating the ear’s air route from its bone route. The Rinne test compares sound heard beside the ear with sound heard through the skull behind it. The Weber test sends vibration through the midline of the skull and asks where the sound seems strongest. If air conduction is reduced but bone conduction still reaches the inner ear, the pattern points to conductive hearing loss in the outer or middle ear. If bone and air routes are affected together, the problem is more likely sensorineural, involving the cochlea or hearing nerve.
What the Rinne test compares
The Rinne test uses a vibrating tuning fork in different positions around the same ear. First, the fork sits against the mastoid bone behind the ear, so vibration travels through bone. Then it is held beside the ear canal, so sound travels through air.
In typical hearing, the air route sounds clearer or lasts longer. That is because air conduction uses the full hearing system: the ear canal, eardrum, middle-ear bones and inner ear all contribute to the signal.
If the bone route sounds stronger than the air route, the result points towards conductive hearing loss. Something is stopping airborne sound from reaching the inner ear well. The inner ear may still respond when the skull carries the vibration around the blockage.
If the air route still sounds stronger, the Rinne test does not show a conductive block. The hearing may be normal, or the loss may be sensorineural, where the inner ear or hearing nerve has reduced sensitivity to sound however it arrives.
What the Weber test adds
The Weber test looks for imbalance between the ears. The clinician places the vibrating tuning fork on the centre of the forehead or another midline point on the skull. The vibration travels through bone towards the left and right inner ears.
If hearing is balanced, the sound usually feels centred. If the sound seems louder on the affected side, that pattern can point towards conductive hearing loss there. The blocked air route reduces outside sound, so the bone-conducted tuning fork can seem more prominent.
If the sound seems louder in the better-hearing ear, that pattern can point towards sensorineural loss on the other side. The damaged cochlea or nerve does not register the vibration as well, even when the sound bypasses the outer and middle ear.
The Weber test is most useful when paired with Rinne. Rinne asks whether air and bone conduction behave differently in an ear. Weber asks how bone-conducted sound compares between ears.
Why bone conduction is the key trick
Bone conduction is the whole reason these tests work. Normally, sound enters through the ear canal, moves the eardrum, passes through the middle ear, and reaches the cochlea. The cochlea turns vibration into nerve signals for the brain.
A tuning fork can take a shortcut. When its stem touches the skull, vibration reaches the cochlea through bone instead of through the ear canal and middle ear. That makes bone conduction a medical tool, not just a curiosity of hearing.
This shortcut separates where the fault is likely to be. A conductive problem affects the air route before sound reaches the cochlea. A sensorineural problem affects the cochlea or nerve after either route has delivered vibration. Tuning fork tests do not replace formal hearing tests, and they do not identify every cause. They give a quick, physical clue about where the hearing pathway is breaking down.