Weber test
Encyclopedia
The Weber test is a quick screening test for hearing. It can detect unilateral (one-sided)
conductive hearing loss
and unilateral sensorineural hearing loss
. The test is named after Ernst Heinrich Weber
(1795–1878).
Its value as a screening test has been questioned.
(either 256 or 512 Hz) is placed in the middle of the forehead, chin, or head equidistant from the patient's ears. The patient is asked to report in which ear
the sound is heard louder.
In a normal patient, the sound is heard equally loud in both ears (no lateralization). However, a patient with symmetrical hearing loss will hear the sound equally as well. Thus, there is diagnostic utility only in asymmetric hearing losses.
In an abnormal patient, the sound is heard louder in one ear (lateralization). This should be confirmed by repeating the procedure and having the patient occlude one ear with a finger; the sound should be heard best in the occluded ear.
would hear the tuning fork loudest in the affected ear. This is because the conduction problem masks the ambient noise of the room, whilst the well-functioning inner ear
picks the sound up via the bones of the skull causing it to be perceived as a louder sound than in the unaffected ear. Another theory, however, is based on the occlusion effect
described by Tonndorf et al. in 1966. Lower frequency sounds (as made by the 512Hz fork) that are transferred through the bone to the ear canal escapes from the canal. If an occlusion is present, the sound cannot escape and appears louder on the ear with the conductive hearing loss
.
Conductive hearing loss can be mimicked by plugging one ear with a finger and performing the Rinne and Weber tests, which will help clarify the above. The simulation of the Weber test is the basis for the Bing test
.
will produce an apparently normal test result.
, a quick screening test can be made by complementing the Weber test with the Rinne test
.
The Rinne test is used in cases of unilateral hearing loss and establishes which ear has the greater bone conduction. Combined with the patient's perceived hearing loss, it can be determined if the cause is sensorineural or conductive.
For example, if the Rinne test shows that air conduction (AC) is greater than bone conduction (BC) in both ears and the Weber test lateralizes to a particular ear, then there is sensorineural hearing loss in the opposite (weaker) ear. Conductive hearing loss is confirmed in the weaker ear if bone conduction is greater than air conduction and the Weber test lateralizes to that side. Combined hearing loss is likely if the Weber test lateralizes to the stronger ear and bone conduction is greater than air conduction in the weaker ear.
ADDITIONAL CLARIFICATION
The Weber test reflects conduction loss in the ipsilateral ear because, in the event of impaired conduction, ipsilateral sensorineural hearing is perceived as louder; this is the same reason humming becomes more salient when covering the ears.
If the Weber-lateralized ear has a positive Rinne test (AC>BC), that generally means the absence of conduction loss in that ear, and the reason sound had been perceived as louder on that side is because a sensorineural loss is present contralaterally; an ipsilateral negative Rinne test (BC>AC), on the other hand, would confirm ipsilateral conductive hearing loss (although contralateral sensorineural hearing loss may still be present.
If the Weber-lateralized ear has a positive Rinne test and the contralateral ear has a negative Rinne test, then both conductive and senorineural hearing loss are present in the contralateral ear. This is because sensorineural deficits always take auditory precedent over conductive ones, so even though conductive hearing loss is present in the contralateral ear, it is the sensorineural deficit that is responsible for the ipsilateral perceived elevation of volume.
This also means that a Weber-lateralized ear with bilateral negative-Rinne corresponds to only sensorineural hearing on the ipsilateral side not being affected.
Unilateral hearing loss
Unilateral hearing loss or single-sided deafness is a type of hearing impairment where there is normal hearing in one ear and impaired hearing in the other ear.-Signs and symptoms:Patients with unilateral hearing loss have difficulty in...
conductive hearing loss
Conductive hearing loss
Conductive hearing loss occurs when there is a problem conducting sound waves anywhere along the route through the outer ear, tympanic membrane , or middle ear ....
and unilateral sensorineural hearing loss
Sensorineural hearing loss
Sensorineural hearing loss is a type of hearing loss in which the root cause lies in the vestibulocochlear nerve , the inner ear, or central processing centers of the brain....
. The test is named after Ernst Heinrich Weber
Ernst Heinrich Weber
Ernst Heinrich Weber was a German physician who is considered one of the founders of experimental psychology.Weber studied medicine at Wittenberg University...
(1795–1878).
Its value as a screening test has been questioned.
Performance
In the Weber test a vibrating tuning forkTuning fork
A tuning fork is an acoustic resonator in the form of a two-pronged fork with the prongs formed from a U-shaped bar of elastic metal . It resonates at a specific constant pitch when set vibrating by striking it against a surface or with an object, and emits a pure musical tone after waiting a...
(either 256 or 512 Hz) is placed in the middle of the forehead, chin, or head equidistant from the patient's ears. The patient is asked to report in which ear
Ear
The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....
the sound is heard louder.
In a normal patient, the sound is heard equally loud in both ears (no lateralization). However, a patient with symmetrical hearing loss will hear the sound equally as well. Thus, there is diagnostic utility only in asymmetric hearing losses.
In an abnormal patient, the sound is heard louder in one ear (lateralization). This should be confirmed by repeating the procedure and having the patient occlude one ear with a finger; the sound should be heard best in the occluded ear.
Detection of conductive hearing loss
A patient with a unilateral conductive hearing lossConductive hearing loss
Conductive hearing loss occurs when there is a problem conducting sound waves anywhere along the route through the outer ear, tympanic membrane , or middle ear ....
would hear the tuning fork loudest in the affected ear. This is because the conduction problem masks the ambient noise of the room, whilst the well-functioning inner ear
Inner ear
The inner ear is the innermost part of the vertebrate ear. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:...
picks the sound up via the bones of the skull causing it to be perceived as a louder sound than in the unaffected ear. Another theory, however, is based on the occlusion effect
Occlusion effect
The occlusion effect occurs when an object fills the outer portion of a person's ear canal, and that person perceives "hollow" or "booming" echo-like sounds of their own voice. It is caused by bone-conducted sound vibrations reverberating off the object filling the ear canal...
described by Tonndorf et al. in 1966. Lower frequency sounds (as made by the 512Hz fork) that are transferred through the bone to the ear canal escapes from the canal. If an occlusion is present, the sound cannot escape and appears louder on the ear with the conductive hearing loss
Conductive hearing loss
Conductive hearing loss occurs when there is a problem conducting sound waves anywhere along the route through the outer ear, tympanic membrane , or middle ear ....
.
Conductive hearing loss can be mimicked by plugging one ear with a finger and performing the Rinne and Weber tests, which will help clarify the above. The simulation of the Weber test is the basis for the Bing test
Bing test
The Bing test, was devised by German otologist Albert Bing. The test uses a low-frequency tuning fork to test for the occlusion effect. The tuning fork can be replaced by a bone-conduction vibrator in the audiometric Bing test....
.
Detection of sensorineural hearing loss
A patient with a unilateral sensorineural hearing loss would hear the sound louder in the unaffected ear, because the affected ear is less effective at picking up sound even if it is transmitted directly by conduction into the inner ear.Incompleteness
This test is most useful in individuals with hearing that is different between the two ears. It cannot confirm normal hearing because it does not measure sound sensitivity in a quantitative manner. Hearing defects affecting both ears equally, as in PresbycusisPresbycusis
Presbycusis, or age-related hearing loss, is the cumulative effect of aging on hearing. Also known as presbyacusis, it is defined as a progressive bilateral symmetrical age-related sensorineural hearing loss. The hearing loss is most marked at higher frequencies...
will produce an apparently normal test result.
Additional Rinne test
Although no replacement for formal audiometryAudiometry
Audiometry is the testing of hearing ability, involving thresholds and differing frequencies. Typically, audiometric tests determine a subject's hearing levels with the help of an audiometer, but may also measure ability to discriminate between different sound intensities, recognize pitch, or...
, a quick screening test can be made by complementing the Weber test with the Rinne test
Rinne test
The Rinne test is a hearing test. It compares perception of sounds transmitted by air conduction to those transmitted by bone conduction through the mastoid...
.
The Rinne test is used in cases of unilateral hearing loss and establishes which ear has the greater bone conduction. Combined with the patient's perceived hearing loss, it can be determined if the cause is sensorineural or conductive.
For example, if the Rinne test shows that air conduction (AC) is greater than bone conduction (BC) in both ears and the Weber test lateralizes to a particular ear, then there is sensorineural hearing loss in the opposite (weaker) ear. Conductive hearing loss is confirmed in the weaker ear if bone conduction is greater than air conduction and the Weber test lateralizes to that side. Combined hearing loss is likely if the Weber test lateralizes to the stronger ear and bone conduction is greater than air conduction in the weaker ear.
| Weber without lateralization | Weber lateralizes left | Weber lateralizes right | |
|---|---|---|---|
| Rinne both ears AC>BC | Normal | Sensorineural loss in right | Sensorineural loss in left |
| Rinne left BC>AC | Conductive loss in left | Combined loss : conductive and sensorineural loss in left | |
| Rinne right BC>AC | Combined loss : conductive and sensorineural loss in right | Conductive loss in right | |
| Rinne both ears BC>AC | Combined loss in right and conductive loss on left | Combined loss in left and conductive loss on right |
ADDITIONAL CLARIFICATION
The Weber test reflects conduction loss in the ipsilateral ear because, in the event of impaired conduction, ipsilateral sensorineural hearing is perceived as louder; this is the same reason humming becomes more salient when covering the ears.
If the Weber-lateralized ear has a positive Rinne test (AC>BC), that generally means the absence of conduction loss in that ear, and the reason sound had been perceived as louder on that side is because a sensorineural loss is present contralaterally; an ipsilateral negative Rinne test (BC>AC), on the other hand, would confirm ipsilateral conductive hearing loss (although contralateral sensorineural hearing loss may still be present.
If the Weber-lateralized ear has a positive Rinne test and the contralateral ear has a negative Rinne test, then both conductive and senorineural hearing loss are present in the contralateral ear. This is because sensorineural deficits always take auditory precedent over conductive ones, so even though conductive hearing loss is present in the contralateral ear, it is the sensorineural deficit that is responsible for the ipsilateral perceived elevation of volume.
This also means that a Weber-lateralized ear with bilateral negative-Rinne corresponds to only sensorineural hearing on the ipsilateral side not being affected.