Tuning fork test

All about tuning fork test

1. Tuning Fork Tests
What is tuning fork?
A tuning fork is an acoustic resonator which has a handle (stem) and two prongs (or tines; U-
shaped). It is made up of metal like steel, aluminum, alloy etc. It was invented by British musician
John Shore (1711) to tune musical instruments. Later it was used in musical instruments, clocks and
watches, physics experiments, Tuning Fork tests in Audiology and Otology etc.
How tuning fork tests came into existence.
Prior to the inception of audiometer and audiologist, otologists relied on as many as 20 tuning fork
tests in order to determine the type of hearing loss especially to distinguish conductive hearing loss
with sensorineural hearing loss [1, 2].
Some also tried to estimate degree of hearing loss, though the measure was never
successful/sensitive when compared to find the type of hearing loss.
Tuning forks in Audiology and Otology
Available tuning forks can produce wide range of frequencies i.e. from 64 Hz to 4096 Hz. In
Audiology and otology; 128, 256, 512 and 1024 Hz are used for testing.
But the preferred tuning fork is a 512Hz tuning fork. At this frequency the tone does not fade too
quickly. Frequencies less that 256Hz are vibrotactile and above 1024 Hz are difficult to hear. [2-4]
Maximum intensity that can be produce by tuning fork: When struck accurately the tuning fork
should be heard with 40-50 dBHL of bone conduction hearing threshold levels. [5]
Tuning Fork Tests: Weber, Rinne, Bing, Schwabach, ABC are commonly known tuning fork tests.
Weber Test
 Was named after Ernst Heinrich Weber reported by Jean Pierre Bonnafont [2, 9]
 Principle
o This test is useful in identifying unilateral hearing loss. A patient with a unilateral
conductive hearing loss (CHL) would hear the tuning fork loudest in the affected ear.
This is because the conduction problem masks the ambient noise of the room, whilst

2. 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.
o Based on Stenger principle: When two tones of unequal loudness introduced to the
ear simultaneously, only the louder will be heard.
 Procedure: Place the stem of a vibrating tuning fork on the skull in the midline. The patient
is asked to indicate in which ear the sound is heard.
 Interpretation
o With symmetrical hearing or a symmetrical hearing loss the sound should be central
o With an asymmetrical sensorineural loss the sound should be heard in the better ear
o With an asymmetrical conductive hearing loss the sound should be heard in the
poorer ear
 Points to note:
o Thiagarajan & Arjunan (2012) suggest the Weber test can determine a difference of 5
decibels between each ear in terms of bone conduction thresholds at the frequency
being tested. [6]
o This test can be complicated by the presence of a unilateral or asymmetrical
conductive hearing loss, where the tone can be heard on the conductive side or the
side with the greater conductive loss. Interpretation of the Weber test in isolation can
be prone to error.
o Some patients refuse to accept the fact that the tuning fork may be heard in the
"deaf" ear, the one with a conductive impairment, and will indicate just the opposite.
One can be mislead and must be aware of this possibility.
o The Bing test will usually clarify; this will be discussed later.
o The usual location described for placement of the fork is the forehead. Better
locations are the nasal bones or teeth; a stronger bone conduction stimulus is
presented. This stronger stimulus is particularly helpful in identifying cases with an
audiometrically nonmeasurable air-bone gap, the far-advanced otosclerotics.
Although you may not be able to detect mastoid bone conduction with the
audiometer, a strongly stimulated tuning fork placed on the teeth should clearly
indicate the presence of bone conduction, and to which ear the fork is lateralized

3. Rinne test
 Adolf Rinne take a step more than Weber Test by comparing bone conduction with air
conduction [2, 9]
 The Rinne test is probably the most commonly used of the tuning fork tests, but the name is
usually mispronounced. It is German, not French, and is accented on the first syllable
(Rin'neh).
 Principle—The Rinne test is a comparison of the sound intensity of a vibrating tuning fork
placed on the mastoid with its intensity when held next to the ear.
o Proper placement of the tuning fork in each situation is important. When testing by
bone conduction, place the stem of the fork firmly on the mastoid, over the
perforated area, as near to the posterior-superior edge of the ear canal as possible.
Placement here avoids the variable factor of soft tissue thickness.
o Do not let the stem of the fork touch the auricle; this could give false results due to
vibrations of the auricle.
o When testing by air conduction hold the fork about one inch lateral to the tragus.
The tines should be parallel to the frontal plane of the skull.
 Interpretation
o If air conduction (next to the ear canal) is louder, this is a Rinne positive result,
indicating either normal hearing or a sensorineural hearing loss
o If bone conduction (held on mastoid) is louder, this is a Rinne negative result,
indicating a significant conductive element to the hearing loss
 Points to note
o Conductive deficit of 15 dB or more reverses the tuning fork response (bone
conduction better than air conduction) at 512 Hz, and that a 20-dB deficit or more
reverses the response to a 1024 Hz tuning fork.
o The Rinne test is able to distinguish a conductive hearing loss with an air-bone gap
of 17.5 dB - 30 dB. [7, 8] It therefore has limited utility in detecting mild conductive
hearing losses or mixed hearing losses where there is an air-bone gap of less than
17.5dB

4. o When testing by bone conduction, do not forget to have the patient remove his
glasses. The spatula can interfere with proper placement of the stem of the tuning
fork in the area of maximum intensity.
o Responses to the Rinne test vary with the examiner's technique. If the stem of the
fork is improperly placed on the mastoid (wrong location or not enough pressure),
the patient may hear air conduction better than bone conduction even though a
significant air-bone gap exists. In this same situation, air conduction can sound
louder than bone conduction if the tines of the fork are held too close to the external
auditory meatus. Each student learns his norms by careful and repeated testing,
comparing his findings with those of his teacher's, with the audiogram, and with the
results following surgery.
o The tester should be aware that the Rinne test can result in a False Rinne Negative.
 This occurs when the bone conduction transmits through the skull to the
opposite ear and is detected through cross hearing by the better cochlea (in
the non-test ear). This occurs with a severe sensorineural loss predominantly
on the test side. It can be distinguished through considering if the Weber test
result is contradictory and through asking the patient which ear the bone
conduction part of the test was heard in. This can be taking care by masking.
Masking is very important in audiometry and is equally important when
performing the Rinne test, particularly in unilateral cases. Note that a Bárány
noise apparatus is used in the nontest ear. We keep one of these old-
fashioned, but dependable, apparatuses in each of our treatment rooms.
There is some variation between the noise output of noisemakers; test your
Bárány apparatus on your own ear to determine how much masking to
expect. The tip of the noisemaker usually should not be placed in the external
auditory meatus, but merely adjacent to it Placed in the meatus and
occluding it, it could overmask, or it could even produce a temporary
threshold shift in a susceptible individual. Masking of the non-test ear can
also be done through the use of tragal rubbing can prevent cross hearing.
The tester should place their index finger and thumb either side of the tragus
and massage the outside of the tragus to create the masking noise. Please
note this is not always efficient and is hard to interpret and it is

5. recommended that if it is required the patient undergoes a fully masked pure-
tone audiogram
Schwabach Test
 This test was described by the German otologist, Dagabarth Schwabach, for evaluating bone
conduction. [9]
 Principle: Comparison of the BC of patient and clinician.
 Place a vibrating tuning fork on the mastoid and ask the patient to indicate when he stops
hearing the tone. Immediately apply the tuning fork to your own mastoid; do you hear the
tone?
 Interpretation.—Schwabach described his test as a comparison of how long the sound was
heard by the patient and examiner. We compare only the end points. Is the bone conduction
better than, equal to, or worse than clinician's?
o Normal Schwabach - Equal BC, both patient and clinician stop hearing tone at the
same time. Patient has normal BC
o Diminished Schawabach – Patient stop hearing sooner than clinician. Patient has
abnormal BC which means SNHL
Absolute Bone Conduction (ABC)
o It is a modification of Schwabach test.
o In this everything is same expect, ear canal is occluded by pressing the tragus inwards to
block noise entering through air conduction.
o Clinician should have normal BC
o Interpretation
o ABC reduced - SNHL - Clinician listens longer than patient
o ABC normal – Normal hearing - Clinician listens equal to that of patient
o ABC lengthened – Conductive - Patient listens longer than clinician
Bing Test
 The test described by Albert Bing in 1891. [10]

6.  Bing described as "secondary perception" the prolongation of bone conduction that
accompanied occlusion of the ear canal when the conductive mechanism was normal.
 Technique.—Place a vibrating tuning fork on the skull (mastoid or midline) and note
lateralization, if any. Occlude the external auditory canal gently without causing pressure on
the tympanic membrane. Ask the patient to indicate if this maneuver increases the sound
intensity or results in a shift of bone conducted sound to the occluded ear.
The test may also be performed by occluding the external auditory meatus only after the
patient indicates he no longer hears the bone conducted sound. Does he experience
"secondary perception," does he again hear the sound.
 Interpretation
o Positive Bing Test – Normal hearing or SNHL – Louder when occluded- When the
conduction mechanism is normal, occlusion of the ear canal results in an
intensification of the bone conducted sound in that ear. In a person with normal
hearing, then, or in one with a sensorineural hearing impairment, occlusion of the
canal should cause a shift of the sound to that ear or an intensification of the sound
if it is already being heard in that ear.
o Negative Bing – Conductive hearing loss – No change - When there is a significant
conductive impairment, however, occlusion will have no noticeable effect.
 Points to note
o The Bing test is actually more valuable in our hands than the Rinne test in
differentiating between a conductive and a sensorineural impairment. It does not
demand that the patient make a comparison of intensity and it does not vary as much
with the technique of the examiner as does the response to the Rinne test. In
practice, we use this test primarily when responses to the Weber and Rinne have left
us uncertain as to the type of impairment present. This will happen at times with an
apparent mixed impairment where the conductive component is minimal and the
tympanic membrane is intact. Is there any conductive component? Is this perhaps
otosclerosis? The patient may not lateralize the fork and he is uncertain regarding the
comparison of air conduction and bone conduction. Applying the Bing test usually
clarifies this matter.

7. o A word of caution: Some patients may become confused by the intensification of
sound in the occluded ear when the conductive mechanism is normal in that ear. As
a result, you may be told that the tone has become softer or has shifted to the
unoccluded ear; you must realize that this is not possible. When this happens it may
help to retest the patient, asking only whether there is a change in the tone when the
ear is occluded. For those unfamiliar with the Bing test it may require a bit of
practice to learn the usual responses.
Tips of striking tuning forks: Lower the pitch of the tuning fork, softer the material to be used for
striking. Lower – side of hand; medium – rubber tip stiker and high - metal hammer are used.
Variablity in the results of TFTs and factors affect the results of TFTs
 This variability may be due to numerous factors, including clinical technique or experience of
audiologist/otologist, clinical environment (background noise), tuning fork size or material,
and patient factors (like attending, understandability of instructions) [2].
 Other source of error in the use of tuning fork is the distance fork kept from the ear [2, 9]
 The reported air-bone gap (ABG) necessary for detection of a conductive hearing loss by
Rinne testing ranges between 15 dB and 40 dB [2-5].
Other tuning fork tests [2, 9]
 The Gelle Test – developed to determine the mobility of the footplate of stapes.
 The Stenger tuning fork test – for presumed functional unilateral deafness
 Chandler tuning fork test for recritment.
Advantages of tuning fork tests
 Easy to perform
 Can even be performed at bed side
 Will give a rough estimate of the patient’s hearing acuity

8. Other important notes
 Though most of the TFTs extinct due to the technological advancement. Test like Weber
and Rinne are still used by surgeon at least to recheck the type of hearing loss diagnosed
using Air-Bone-Gap determined by audiometers.
 Roles in current practice, including screening for hearing loss, confirmation of audiometry,
estimation of hearing loss severity, and verification of surgical candidacy [1, 12]
 How mixed loss patient behave with TFTs? Like mixed conductive hearing loss [13]
 It is difficult for many of us to remember the meaning of "positive" and "negative" as
applied to tuning fork test. The problem is that normal tuning fork responses are called
positive, and abnormal fork responses, the ones that we are looking for, are called negative.
This is confusing because it is just the opposite from the terminology used for test results in
most of medicine; abnormal responses usually are termed positive.
Concluding remark: Tuning fork tests may be a bit old-fashioned, but they are far from outdated.
They should be used routinely by the Audiologist and Otologist. This is part of the art as well as the
science applied to Audiology and otology.
References
1. Ng M, Jackler RK. Early history of tuning-fork tests. Am J Otol. 1993;14:100-105.
2. Johnson EW: Tuning forks to audiometers and back again. Laryngoscope 80:49-68, 1970.
3. Khanna, S., Tonndorf, J. & Queller, J. (1976) Mechanical parameters of hearing by bone
conduction. Journal of Acoustic Society of America.60(1):139-54
4. Tonndorf, J. (1968) A new concept of bone conduction. Arch Otolaryngology. 87(6):595-
600
5. Stankiewicz, J. A., & Mowry, H. J. (1979). Clinical accuracy of tuning fork tests. The
Laryngoscope, 89(12), 1956-1963.
6. Thiagarajan, B., & Arjunan, K. (2012) Tuning Fork Tests. WebmedCentral:ENT Scholar
3(4):WMC003279
7. MacKechnie, C. A., Greenberg, J. J., Gerkin, R. C., McCall, A. A., Hirsch, B. E., Durrant, J.
D., & Raz, Y. (2013). Rinne revisited: steel versus aluminum tuning forks. Otolaryngology–
Head and Neck Surgery, 149(6), 907-913.

9. 8. Burkey JM, Lippy WH, Schuring AG, et al. Clinical utility of the 512-Hz Rinne tuning fork
test. Am J Otol. 1998;19:59-62.
9. Sheehy JL, Gardner G Jr, Hambley WM. Tuning fork tests in modern otology. Arch
Otolaryngol. 1971;94:132-138.
10. Swan, I. R. C., & Browning, G. G. (1989). The Bing test in the detection of conductive
hearing impairment. Clinical Otolaryngology & Allied Sciences, 14(6), 539-541.
11. Crowley H, Kaufman RS. The Rinne tuning fork test. Arch Otolaryngol. 1966;84:406-408
12. Hildyard VH, Stool SE, Valentine MA. Tuning fork tests as aid to screening audiometry:
report on a preliminary field study. Arch Otolaryngol Head Neck Surg. 1963;78:151-154.
13. Miltenburg, D. M. (1994). The validity of tuning fork tests in diagnosing hearing loss. The
Journal of otolaryngology, 23(4), 254-259.
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