TUNING FORK TEST

Moderator-Dr.Narayana SwamyPresenter-Dr.Razal M Sherif

Tuning Fork • Is a small metal instrument consisting

of a stem, two prongs and a foot Piece, that produces a constant pitch when either prong is struck against a firm but resilient surface.

• It is usually made of steel, magnesium or aluminum that is used to tune musical instruments by musicians and now used by doctors to assess hearing.

• It vibrates sinusoidally to generate a pure tone

Tuning Fork Test• Used to differentiate between conductive and

sensorineural hearing loss.• Test is performed with different types of

frequency like 128,256,512, 1024,2048 Hz. Routine practices 256Hz,512 Hz,1024Hz are used.

• Larger forks vibrate at slower frequency.• Tuning fork is activated by striking against

examiner's elbow, heel of hand and placed 2cm away from EAC for Air conduction and on mastoid for Bone conduction.

Air Conduction (AC)• Vibrating tuning fork is placed vertically in line

with the meatus about 2 cm away from the EAC opening.

• The sound waves transmitted through TM –Middle ear ossicles-Inner ear –Auditory Nerve –Auditory Cortex.

• Both Conductive mechanism and Cochlea are tested

Bone Conduction (BC)• Foot plate of Vibrating tuning fork is placed on the

mastoid bone.• Cochlea is stimulated directly by the vibrations

conducted through the Skull.• BC measures only the cochlear functions.• Normally AC will be more than BC

Principles of Tuning Fork Tests

• Conductive Hearing loss (CHL)o Sounds delivered to the ear via AC will be

decreased o If the sound is delivered to the ear via BC,

bypassing the OE & ME, then the sound will be heard normally assuming there is no disorder.

• Sensory Hearing Loss (SNHL)o Sounds delivered to the ear via BC will be

deceased.

Types

• Rinne Test• Weber Test• ABC test• Schwabach Test• Gelle’s Test• Bing Test

RINNE Test • Proposed by Heinrich Adolf Rinne(1855)• Air conduction is compared with bone

conduction • The base of Vibrating tuning fork is placed firmly

over mastoid process,• Patient is asked to indicate when sound

disappears, suddenly the tuning fork is placed vertically 2cm from EAC,

• If hears still –AC more than BC.• Rinne Positive.ie,Normal.

Inference • Rinne Positive

o Air Conduction >Bone Conduction=Normal or SNHL• Rinne Negative

o Bone Conduction >Air Conduction =Conductive hearing Loss

• False Negative Rinneo Air conduction absent, but responds to bone conductiono Response of bone conduction is due to transcranial

transmission from opposite earo Seen in UNILATERAL SENSORY HEARING LOSS.

Modified Rinne

• For routine purpose ,the patient is asked to compare the sound intensities of tuning fork, while placing in front of the ear and over the mastoid process.

WEBER Test• Proposed by Ernst Heinrich Weber.• A test of lateralization• A vibrating tuning fork is placed in the middle of

forehead or the vertex asked in which ear the sound is heard.

• Normally, heard equally in both ears.• Lateralized to the worst ear in conductive hearing

loss and better in Sensory neural loss ear.• Sound travels directly to the cochlea through

bone.

WEBER Test• Based on “Stenger Principle”:

o If two tones are identical except they are different in loudness, are introduced simultaneously into both ears, only the louder tone will be perceived

o Two ears, one has poorer BC sensitivity, when the tone is being produced to both ears with equal energy, the tone will be perceived softer or will not be perceived at all in the poor ear.

Inference • If the tone lateralizes to the poorer ear

• CHL in the poor ear

• If the tone lateralizes to the better/good ear:• The cochlea with the best hearing sensitivity will detect the

signal• SNHL in the poor ear

• If the sound is detected in the midline position:• Normal hearing• or equal amounts of the same type of HL in both ears (CHL,

SNHL)

SCHWABACH Test • Once popular but no longer is in use.• It compares pts. hearing sensitivity with that of an examiner

(assuming that he/she has a normal hearing).

• The fork is set into vibration, stem is placed alternately against the mastoid process of the pt. and the examiner. Here meatus is not closed.

• Vibratory energy of the tines of fork decreases overtime, making the tone softer

• Pt. should indicate whether the tone is heard or not each time

• When the pt. no longer hears the tone, examiner immediately places the stem behind his or her own ear and using a watch, notes the number of seconds the tone is audible after the pt. stops hearing it

Inference • Normal Schwabach:

o Both pt. & examiner stop hearing the tone at approximately the same time • Pt. has normal BC

• Diminished Schwabach:o Pt. stop hearing the sound much sooner than the

examiner• Pt. BC is impaired/SNHL

Absolute Bone Conduction(ABC)• Modification of Schwabach test.• Patients bone conduction is compared with that of

the examiner (assuming that he/she has a normal hearing).

• EAC is occluded, by pressing the tragus inwards,to prevent ambient noise entering through AC route.

• Inference o Normal –Bone conduction of patient is equal to

examinero In SNHL ABC is reduced in comparison to examiner.

GELLE’s Test• Test of bone conduction.• Examines the effect of increased air pressure in

ear canal.• Performed by vibrating fork on the mastoid • By Increasing the pressure in the EAC with a

Siegel's speculum, it pushes the TM and ossicles inwards, raises the intralabyrinthine pressure and causes immobility of basilar membrane and decreased hearing, but no change in hearing when ossicles are fixed.

GELLE’s Test• Inference

o Negative-When ossicular chain is fixed in case of Otosclerosis or disconnected

o Positive –Normal case and SNHL

• This test is replaced with Tympanometry.

BING’s Test• Proposed by Albert Bing• It is test of Bone Conduction.• Examines the effect of Occlusion of ear canal on

hearing.• Vibrating tuning fork is placed on the mastoid

while examiner alternatively closes and open the ear canal by pressing tragus inward.

• Inference o Normal or SNHL hears louder when canal is occluded

and softer when the canal is open-BING POSITIVEo CHL patients will appreciate no change.-BING NEGATIVE

Tuning Fork Tests For Malingering

• Stenger’s test: o This is based on “Stenger’s phenomenon”, when a listener is

presented with the same type of sound in both ears he will hear a single sound, that too only in the ear which it is louder.Procedure: Two tuning forks with frequency of 512 Hz are kept equidistantly from both ears, one should be able to hear equally well in either side. In malingering say i.e. left ear, even if the tuning fork is moved too close to the left ear, the patient denies that he is hearing in the right side also.

• Teal’s test: o In this test a vibrating tuning fork is applied over the mastoid

process of the so called deaf ear, the patient accepts to hear it. Then the patient is blind folded and with a non vibrating fork on the mastoid process, the malingering patient claim’s to hear the sound.

• Chimani Mooss test: o A variation of Weber’s test. Normally in Weber’s test the

patient hears the best in the occluded ear. In ,malingering the patient will not accept to hear better in the occluded ear.

Tuning Fork Tests For Malingering

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