8/2/2023 0 Comments 256 hz tuning fork![]() ![]() ![]() Note that the words positive and negative are used in a somewhat confusing fashion here, as compared to their typical use in medical tests. In an ear with conductive hearing loss, bone conduction (BC) is better than air conduction (AC) In an ear with normal hearing and an ear with sensorineural hearing loss, air conduction (AC) is more than bone conduction (BC) bone conductive hearing loss Īir conduction uses the apparatus of the middle ear ( pinna, eardrum and ossicles) to amplify and direct the sound to the cochlea, whereas bone conduction bypasses some or all of these and allows the sound to be transmitted directly to the inner ear albeit at a reduced volume, or via the bones of the skull to the opposite ear. It is caused by the fact that even though one ear is unable to respond to the test, the other ear can still be stimulated by the bone conduction test (via conducting sound through skull bones to the opposite ear), causing the patient to respond to the tuning fork on mastoid but not when it's placed near the affected ear's air canal. In case of a severe sensorineural hearing loss caused due to a dead labyrinth, a false negative Rinne test may occur.This can be revealed by the person administering the test (with normal hearing) placing the fork close to their own ear after the patient indicates that the sound has subsided, noting that the sound from the fork is still noticeable to a normal ear. This pattern is the same to what is found in people with normal hearing, but patients with sensorineural hearing loss will indicate that the sound has stopped much earlier. In sensorineural hearing loss the ability to sense the tuning fork by both bone and air conduction is equally diminished, implying they will hear the tuning fork by air conduction after they can no longer hear it through bone conduction.This indicates there is something inhibiting the passage of sound waves from the ear canal, through the middle ear apparatus and into the cochlea (i.e., there is a conductive hearing loss). If the patient is not able to hear the tuning fork after it is moved from the mastoid to the pinna, it means that their bone conduction is greater than their air conduction (BC>AC).This normal result is paradoxically called a positive Rinne test (as a positive medical test usually indicates an abnormality). ![]() Air conduction should be greater than bone conduction (AC>BC), so the patient should be able to hear the tuning fork next to the pinna (outer ear) after they can no longer hear it when held against the mastoid.The patient is then asked again to indicate when they are no longer able to hear the tuning fork. Once the patient signals they can't hear it, the still vibrating tuning fork is then placed 1–2 cm from the auditory canal. The Rinne test is performed by placing a 512 Hz vibrating tuning fork against the patient's mastoid bone and asking the patient to tell you when the sound is no longer heard. Placement of the tuning fork in front of the ear, to test air conduction. ![]()
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