4Tuning-Fork Tests (Weber, Rinne)

FWhy a fork still matters in the audiometry era

A patient describes ringing in one ear. Before any machine is switched on, a 512 Hz tuning fork lets you decide, at the bedside, whether the problem lives in the conducting apparatus (canal, drum, ossicles) or in the cochlea and nerve behind it. That single distinction reshapes the differential: a conductive picture points toward wax, effusion or otosclerosis — often reversible — whereas a sensorineural picture raises sensorineural hearing loss, Menière disease or, when asymmetric, a vestibular schwannoma [2013].

The 512 Hz fork is the clinical workhorse because it strikes the best balance between audible tone and minimal tactile vibration. Lower-frequency forks (128 Hz) are felt as much as heard and produce false ‘negatives’; higher forks decay too quickly. The two tests that matter are Weber (lateralisation) and Rinne (air- versus bone-conduction).

TThe logic of Weber and Rinne

In the Weber test the struck fork is placed on the midline — vertex, forehead or upper incisors. Sound delivered by bone conduction reaches both cochleae equally, so in a symmetric ear it is heard centrally. It lateralises toward a conductively impaired ear (the occlusion effect shields that ear from ambient masking noise and bone-conducted sound is heard more easily there) and away from a sensorineural ear (the healthier cochlea wins).

In the Rinne test air conduction (fork held beside the meatus) is compared with bone conduction (fork on the mastoid). Normally air conduction is louder and longer — a positive Rinne. When bone beats air — a negative Rinne — there is a conductive deficit in the tested ear, usually of at least 20–25 dB before the result flips. Read together, the pair localises the lesion: a Weber lateralising to the symptomatic ear plus a negative Rinne on that side confirms conductive loss; a Weber lateralising away with a positive Rinne points to sensorineural loss [2013].

TPatterns in the tinnitus patient

Conductive tinnitus tends to be low-pitched, ‘roaring’ or buzzing, and is the ringing of otosclerosis, middle-ear effusion and impacted wax. Sensorineural tinnitus is more often high-pitched and tonal, the companion of noise-induced and age-related cochlear loss [2013]. The fork therefore does double duty: it predicts the likely character of the tinnitus and the likely cause.

The most clinically loaded pattern is the unilateral high-pitched tinnitus with a Weber lateralising away from that ear and a positive Rinne — asymmetric sensorineural loss. This is the bedside fingerprint that, even with no audiogram yet available, should trigger MRI of the internal auditory canal to exclude a vestibular schwannoma [2014].

CPitfalls and accuracy — what the fork can and cannot do

Tuning-fork tests are screening tools, not measurements. The Rinne becomes negative only once the air–bone gap exceeds roughly 20–25 dB, so small conductive losses are missed; diagnostic-accuracy work shows the Rinne is reasonably specific but insensitive to mild gaps, and clinicians are ‘mistaken’ surprisingly often when the gap is borderline [2021]. The Weber is qualitative and notoriously hard to interpret in symmetric or bilateral loss, where it may sit centrally or wander; its agreement with the audiometric Weber is only moderate [2026] [2022].

Classic traps: a false-negative Rinne (the ‘false-positive’ of dead-ear lore) occurs in profound unilateral sensorineural loss, when the patient hears the mastoid-placed fork through the contralateral cochlea by transcranial transmission and reports ‘bone louder’; masking the opposite ear (Bing/Barany noise) unmasks the deception. Tactile vibration from a low-frequency fork mimics hearing; ambient noise and sinus or canal occlusion can shift Weber lateralisation. The practical rule: use the fork to direct audiometry and imaging, and let pure-tone audiometry quantify what the fork only suggests [2013].