Over the years, many types of tuning forks tests had been developed to assess hearing loss, but today only two have withstood the test of time: Rinne and Weber. Both of these tests are now routinely taught in medical schools and performed regularly to assess patients with hearing problems. Heinrich Adolph Rinne (1819-1868), a German otologist, proposed the test which was subsequently named after him.
The Rinne test is used to evaluate hearing loss in one ear. The Rinne test differentiates sound transmitted through air conduction from those transmitted through bone conduction via the mastoid bone. By comparing air and bone conduction, it helps detect conductive hearing loss in one ear. A Rinne test should be performed in conjunction with a Weber test in order to help distinguish between conductive hearing loss and sensorineural hearing loss.  The Rinne test is frequently recommended when one suspects a conductive hearing loss. In some patients with otosclerosis, the Rinne test is performed to determine if the patient is eligible for stapes surgery.
The external ear collects sound vibrations from the air and focuses these sounds onto the tympanic membrane. Vibrations are transmitted through the middle ear by the ossicular chain (malleus, incus, and stapes). The stapes transmits these vibrations to the cochlea through the oval window (fenestra ovalis). Sound can also be transmitted through the bones of the skull to the cochlea.
The hair cells in the cochlea convert the physical vibrations into action potentials that are transmitted via the nerves in the vestibulocochlear (auditory) nerve to the brainstem for further processing.
Deafness may occur due to interruption at any point along this pathway.
The Rinne test is conducted by placing a tuning fork on the mastoid bone and then adjacent to the outer ear.
Before performing the Rinne test, it is important to know that individuals with normal hearing will have air conduction that is greater than bone conduction. This means that the individual will be able to hear the tuning fork that is placed adjacent to the outer ear, even after they are no longer able to hear it when held against the mastoid.
Use a 512 Hz tuning fork. Please avoid using 128 Hz or 256 Hz tuning fork, as these are used to assess vibration sensation in neurological examinations.
The room should be reasonably quiet.
Test Bone Conduction
Normal finding: Air conduction is better than bone conduction. The patient should be able to hear the sound of the tuning fork, adjacent to their ear, persist for approximately twice as long as the sound they heard over their mastoid process. This is considered a "positive test."
Abnormal: Bone conduction is better than air conduction. The patient cannot hear sound conducted through the air after the fork is moved from the mastoid process. This suggests conductive hearing loss and is referred to as a "negative test."
The Weber test is complementary to the Rinne test. They are screening tests and do not replace formal audiometry.
The tuning fork will be perceived as being louder when placed at the external auditory meatus.
Causes in the external auditory canal:
Causes due to the drum:
Causes in the middle ear:
Causes at the oval window:
False Negative Rinne test
A patient with profound sensorineural deafness may have a false negative Rinne. With complete loss of innervation to that ear, the patient will not hear anything from the tuning fork on the mastoid or near the canal. The sound transmits through their skull to the ear on the other side and they may not be able to identify in which ear they hear the sound.
It seems that bone conduction is better than air conduction, but the ear is nonfunctional.
The way to determine the difference between a true and a false Rinne negative test is to perform the Weber test.
For example, if the left ear is completely dead, on testing the bone conduction on the left, the sound waves travel to the good right ear. But the sounds are not heard when the tuning fork is held next to the external auditory meatus on the side being tested (left). The patient, in this case, will state that bone conduction is louder than air conduction, giving a falsely negative Rinne test.
Limitations of the Rinne test
It is important to remember that the Rinne test is only a screening test and does not replace a formal audiometry test. In addition, the validity of the Rinne test as a screening test is often questioned. The test is not sensitive in differentiating conductive and sensorineural loss causes of total sensorineural or severe unilateral hearing loss. False negatives are common in such situations. In any situation where there is a question about the Rinne test, the patient must be referred to an ear, nose, and throat (ENT) surgeon for formal audiometry.
The other important fact about the Rinne test is that the technique is not uniform. The orientation of the tuning fork and its exact placement vary from individual to individual. All physicians who perform the Rinne test must pay attention to the orientation of the tines of the tuning fork with respect to the long axis of the external auditory canal when testing for air conduction.
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