Examination of hearingThere are two chief classes of hearing loss, and the firststep istodetermine whichis present or whether thehearing loss is of mixed type.The classes are:1.Conductive hearing loss (sometimes still knows asobstuctive or middle ear deafness) This results from anyinterruption to the passage of sound up to and including thestapectio-vertibularjoint. 2.Sensori-neural hearing loss.Various components ofthe sensori-neural system are recognized,but special testsare necessary to identify lesions of indicidual parts.Asensory hearing loss arises when thelesion is inthecochlea.A neural lesion is one in which a lesion affects theeighthnerve
Examination of hearing • There are two chief classes of hearing loss, and the first step is to determine which is present or whether the hearing loss is of mixed type.The classes are: • 1.Conductive hearing loss (sometimes still knows as obstuctive or middle ear deafness) This results from any interruption to the passage of sound up to and including the stapectio-vertibular joint. • 2.Sensori-neural hearing loss.Various components of the sensori-neural system are recognized,but special tests are necessary to identify lesions of indicidual parts.A sensory hearing loss arises when the lesion is in the cochlea.A neural lesion is one in which a lesion affects the eighth nerve
bothMixed hearing loss. In many instancestypes of hearing loss are present
• Mixed hearing loss. In many instances both types of hearing loss are present
Tuning fork testsTuning forks provide a simple,easy and reliablemethod of testing the hearing.A set of256,512,1024,double vibration forks is commonlused.The following are commonly in use:1.Rinne'stest2.Weber's test3.Absolute bone conduction(ABC) test
Tuning fork tests • Tuning forks provide a simple,easy and reliable method of testing the hearing.A set of 256,512,1024,double vibration forks is commonly used.The following are commonly in use: • 1.Rinne's test • 2.Weber's test • 3.Absolute bone conduction(ABC) test
Rinne's test The fork is struck gently on theelbow,knee cap,hypothenar eminence or a rubber pad andheld in such a way so that the prongs vibrate against theear in line with the external canal.The air conduction of thesound iscompared withbone conduction.To test the boneconduction,thefootpieceoftheforksisplacedonthemastoid. The patient is asked to indicate which of the twois louder or where he hears for thelonger timeinterpretation1.Normally air conductionis betterthan boneconduction,which is called Rinne's positive2.Rinne's negative means that bone conduction of thesound isbetterthanair conductionand signifies conductivedeafness
• Rinne's test The fork is struck gently on the elbow,knee cap,hypothenar eminence or a rubber pad and held in such a way so that the prongs vibrate against the ear in line with the external canal.The air conduction of the sound is compared with bone conduction.To test the bone conduction,the foot piece of the forks is placed on the mastoid. The patient is asked to indicate which of the two is louder or where he hears for the longer time. • interpretation • 1.Normally air conduction is better than bone conduction,which is called Rinne's positive. • 2.Rinne's negative means that bone conduction of the sound is better than air conduction and signifies conductive deafness
3.False-negativeA patient with severe unilateral sensorineural loss mayindicate that he hears the bone conducted sound in theaffected ear(test ear)with poor or no response to the airconduction,therefore indicating negative Rinne's test.But inreality, this is false as he is hearing this bone conducted soundacross the skull through the normal ear.Inthese cases,the testisrepeatedbymaskingthenormal earwhiletestingtheaffectedearFig.53Rinne'stest
• 3.False-negative A patient with severe unilateral sensorineural loss may indicate that he hears the bone conducted sound in the affected ear(test ear) with poor or no response to the air conduction,therefore indicating negative Rinne's test.But in reality, this is false as he is hearing this bone conducted sound across the skull through the normal ear. In these cases ,the test is repeated by masking the normal ear while testing the affected ear