What is Rinne Test?
The Rinne test is a hearing test that is carried out to determine the hearing loss on one ear commonly known as a unilateral hearing loss. The Rinne test compares how sounds transmitted by air conduction and those transmitted by bone conduction are perceived through the mastoid. This test is also useful for a quick detection of a conductive hearing loss.
It is important to note that most hearing aid professional will also conduct a Weber test along with a Rinne test. This is to enable them to ascertain if the patient is also experiencing a sensorineural hearing loss.
Over the years, there have been a lot of modifications made to the kinds of tuning fork used in conducting the hearing loss test. In the past, they were different types of test carried out to ascertain hearing loss. Today, however, only two such tests were able to withstand the test of time which are the Rinne and Weber tests.
The Rinne and Weber test have successfully made their way into the medical schools and are taught as standard tests for measuring hearing loss. They have also become the most regular tests carried out on patients with hearing loss problems today. Whenever the hearing loss professional suspects a conductive hearing loss, the Rinne test is prescribed. In cases where some patients are diagnosed with otosclerosis, the Rinne test is conducted to determine if stapes surgery should be conducted or not.
Procedure for conducting Rinne test
the major instrument for performing the Rinne test is a 512Hz tuning fork. This fork is placed against the mastoid bone of the patient. The patient is then asked to indicate when they no longer hear any sound. Once the patient indicates they can no longer hear any sound, the vibrating fork is then placed at a distance of about 2cm from the auditory canal. The patient is then asked to repeat the process of signaling when they can no longer hear any sound.
It is normal that one should have greater air conduction than bone conduction. Where ever it is observed that there is greater bone conduction or equal bone conduction to air conduction, the condition is known as conductive hearing impairment.
Sensorineural hearing loss is the situation whereby the fork vibration is heard longer than normal. It is very important that both the Rinne and Weber tests are performed on both ears. Performing an otoscopic examination for both eardrums will help identify if there is any case of one of the following conditions:
- Severe otitis media
- Tympanic membrane perforation
- External auditory meatus occlusion.
These factors are very important because they can affect the general result of the Rinne and Weber tests. When the test is concluded and a hearing loss is detected, an audiogram is indicated. This will serve as a baseline in the future for reference purposes.
How it works
The hearing process begins from the collection of sound vibrations by the outer ear. These sound vibrations gathered by the outer ear are then sent to the tympanic membrane. Sound vibrations are conveyed through the middle ear by what is known as the ossicular chain. The ossicular chain comprises of the malleus, the incus, and stapes. The stapes is responsible for transmitting sound waves to the cochlea through the fenestra ovalis popularly known as the oval window. Another way sound can be transmitted to the cochlea is through the bones of the skull.
When sound vibrations reach the cochlea, these vibrations are converted into potentials by the hair cells in the cochlea. The potentials are then transferred to the brainstem for further processing through the nerves of the vestibulocochlear (auditory).
When there is an interruption at any point from the sound collection to its processing, this can lead to deafness. Once this occurs, then there is need to carry out a hearing test to determine the cause of the hearing loss and to enable the otologist to proffer the best form of a solution.
The otologist might proceed to conduct a Rinne test and a Weber test to identify the kind of hearing loss and its causes.
In a normal hearing, air conduction is expected to be greater than bone conduction. The patient should be able to still hear the tuning fork when placed next to the outer ear even after they can no longer hear any sound when placed against the mastoid.
An abnormal hearing occurs when the patient can no longer hear the sound of the tuning fork after it has been moved from the mastoid to the pinna. This is a clear indication that the patient’s bone conduction is greater than their air conduction. This situation shows that there is an obstruction in the passage of sound waves from the ear canal down to the inner ear (cochlea). When this situation occurs, it is known as a conductive hearing loss.
In the cases of sensorineural hearing loss, the ability to hear the tuning fork behind the mastoid and against the pinna is completely weakened. Just like people with normal hearing, a patient with sensorineural hearing loss will still hear the sound on the outer ear after it has stopped when placed against the mastoid. However, the difference will be in the duration in which the sound lasted before it stopped. People with sensorineural hearing loss will indicate earlier than expected that the sound has stopped.
This situation can be detected by the person conducting the test who has a normal hearing. He does this by placing the fork against his own ear after the patient has signaled the sound that the sound has stopped. The sound will still be very much noticeable to the normal ear.
Complications and limitations
The Weber test serves as a compliment of the Rinne test. They serve as quick screening tests and do not serve as a replacement for formal audiometry test. Some audiologists and scholars in modern times have questioned the credibility and significance of both Rinne and Weber as in detecting sensorineural and conductive hearing loss problems.
In cases where there is total sensorineural damage or severe unilateral loss, the Rinne test is not reliable as a method of detecting hearing loss. In situations like this, the bone conduction to the contralateral ear not suffering from a hearing loss will feel better than the air conduction. This leads to a false negative. The Weber test, on the other hand, will show signs of lateralization. This suggests some kind of pathology. In cases where there is an abnormal result, a formal audiometry test will be required for clarification of the result.
The tuning fork tests
So far we have come to understand that Rinne and Weber's test is the most common tuning fork tests that is still very much in use today. The Weber test helps to quickly identify the differences in hearing sharpness between both ears. The Rinne test is used to ascertain bone and air conductions in a particular ear. This makes it easier to conduct a differential diagnostics of sensorineural hearing loss from conductive hearing loss.
The Weber test – How it is works
The tuning fork (512 Hz) is set to vibration, the stem is then placed on the midline of the skull. The patient is expected to identify at what side the tone of the vibration is heard, whether center, right or the left ear. For patients with normal hearing ability, the sound is not lateralized to one ear. This means that the sound will be heard centrally and not on one side of the ear. The case is also similar to patients with a side-symmetric sensorineural hearing loss one popular case is what is obtainable in NIHL patients. For patients with one-sided hearing loss, the result of the test depends on the type of hearing loss. For patients experiencing a conductive hearing loss, the sound of the vibration is heard through a damaged ear. For those suffering from sensorineural hearing loss, the tone is heard through the normal-functioning ear.
Application of the Rinne and Weber Test
- Vestibulocochlear nerve
One of the major functions of the vestibulocochlear nerve is to reconcile hearing and balance. The common ways by which hearing can be accessed is by the use of a 512- Hz tuning fork. When it comes to examining the ears for conductive deafness or sensorineural hearing loss, Rinne and Weber's tests are the most commonly applied methods.
When testing for vestibular dysfunction, the movement of the eyes is often put into consideration. When a Nystagmus is noticed on the eye movement, this can be a pointer to vestibular dysfunction. For patients who complain of occasional dizziness, the Dix-Hellpike movement is beneficial for making the diagnosis of benign paroxysmal positional dizziness.
- The Cranial nerve VIII
Assessing the audiometry factor of the cranial nerve requires a hearing test. A hearing test is conducted by blocking one of the ears while whispering into the other ear or by changing sound intensity. The test is conducted separately for both ears. This test is most likely followed by the Rinne and Weber hearing tests.
Some of the things to be noted in this kind of test are the presence of abnormal sensations such as tinnitus or hyperacusis. Where there is the presence of vertigo and nystagmus, it can be as a result of vestibular dysfunction. There are exceptions to this, however, since okulokinetic nystagmus can be a physiological occurrence. The patient’s sensation of objects moving around him can lead to dizziness. Both dizziness and nystagmus can be induced by abrupt changes in the position of the head.
There is another kind of the VIIIth cranial tumor known as the Schwannoma or the acoustic neuroma with is associated initially with only a mild hearing loss. The Schwannoma tumor grows from a kind of cell known as the Schwann cells. This is where the name Schwannoma is derived from. They are not cancerous in most cases. When a Schwannoma is termed a vestibular Schwannoma, it denotes the kind of Schwannoma that affects the nerve responsible for balance (the vestibular nerve). This is one of the major reasons they are referred to as acoustic neuromas by doctors.
Schwannoma can basically grow on any part of the body. However, the most common areas they affect include:
- The brachial plexus (a kind of nerve located at the top of the arm).
- The Sciatic nerve (the main nerve of the leg).
- The sacral plexus (the nerves located at the lower back.)
Test to detect the presence of Schwannoma
It is the duty of the doctor to test and ascertain if you are suffering from Schwannoma. He might be required to carry out blood tests to ascertain your general health. Other tests may include:
- Hearing test.
- MRI scan.
Benefits of the Rinne and Weber tests
Doctors have a lot of benefits from using the Rinne and Weber tests. These tests are easy to perform and can be performed in the office or any reasonably quiet room. These tests often come first before other forms of complex tests used to determine different types of hearing loss. There are a couple of hearing loss conditions that can be identified using the Rinne and Weber tests.
There are also some medical conditions that can lead to abnormal results from Rinne or Weber tests. These conditions include:
Some forms of ear infection
- Ear canal blockage caused by ear wax accumulation.
Accumulation of ear wax can cause ear canal blockage. This can further affect the hearing ability of the patient leading to a false negative result from Rinne or Weber tests.
- Perforation of the eardrum.
This can occur a result of trauma or infection to the ear. Perforation of the eardrum can lead to false negative results from Rinne and Weber tests. Eardrum perforation can affect normal hearing and therefore, the condition needs to be ascertained before carrying out the Rinne and Weber tests.
- Fluid accumulation in the middle ear
Accumulation of fluid in the middle ear can lead to increased pressure in the middle ear comparative to the outer ear. This is most common in children. The blockage of the Eustachian tube leads to the decreased motion of the ossicles as well as the tympanic membrane. Accumulation of fluid in the middle ear causes conductive hearing loss in the middle ear.
- The failure of the small bones of the middle ear to move properly. This is also known as otosclerosis. This leads to poor transmission or no transmission of sound at all from the stapes through the oval window. This can be as a result of abnormal bone growth.
In this situation, it may seem that the bone conduction is better than the bone conduction. This is, however, not the case. The ear rather is not functional. By performing the Weber test, the false negative can be identified.
- Injury to the ear nerves.
An injury to the ear nerve can affect the outcome of the result of the Rinne test. An Injury to the ear nerves can alter the normal functioning of the ear thereby leading to a false negative result.
- Acute otitis media in the middle ear.
This is a form of ear infection that affects the middle ear.
- Serous otitis media.
This situation also called the glue ear can occur as a result of repeated cases of acute otitis media.
The False Negative Rinne Result
In some cases, where we have any of the above problems present, we may have a false negative Rinne result in return. In addition, where we have a total unilateral sensorineural hearing loss, with the left ear totally dead. When a Rinne test is carried out on the left ear, the sound waves will be transferred to the good ear which is the right ear. The sound becomes louder when the tuning fork is held against the external auditory meatus on the left ear. The patient will identify that bone conduction is louder than air conduction. This, in fact, is a false negative report. In situations where there is a conflict in the results from a Rinne test, the doctor will refer the patient to an ear, nose, and throat (ENT) unit for examination and formal audiometry.
It is important to keep in mind that the Rinne test technique is not constant. The way the tuning fork is used and the way it is placed may vary from one person to the other. It is left to the individual conducting the Rinne test to pay close attention to the alignment of the teeth of the tuning fork with reverence to the long axis of the exterior auditory canal when conducting the test for air conduction.
What will be the outcome of Rinne and Weber test results?
The results from both tests will throw emphasis on a possible hearing loss. A follow-up test is required to ascertain if a hearing deficiency is present and what kind. This can help identify the root cause of a hearing loss.
The result obtained from Rinne and Weber tests can help identify what kind of hearing loss the patient is experiencing.
Treating a hearing loss problem.
It is very important to get the ear checked whenever a partial or any form of hearing loss is noticed. A checkup in time can prevent the ear from further going bad. There are some cases where a total loss of hearing ability can be avoided with early diagnosis and treatment. There are also other times where a hearing aid might not necessarily be required to correct a gearing deficiency. Hearing deficiencies caused by partial blockage of the ear canal or those caused by some form of disease conditions are reversible. This is why a visit to your audiologist is very important for general hearing assessment.
The most common treatment for a hearing loss is the use of the hearing aids. There are also some patients who require a cochlear implant in order to improve their hearing. Over the years, the hearing aid has grown more popular and even more effective in performance. There is a lot of design these days with a lot of useful functions. Recently there are hearing aids brand that is designed for better connectivity with external devices such as mobile phones and the other sound systems through the process or simple devices known as the telecoil and teleloop.
Treatment of any hearing deficiency starts with a good examination of the condition by the audiologist. Like every other health conditions, self-medication is not advisable for the hearing loss. It is one of the mistakes some patients make. Instead of going for a proper check-up and medication the resort to the use of traditional methods and other forms of self-medication. These can lead to further complication of the problem as well as cause further damage to the ear.
The importance of the Rinne test cannot be overemphasized. It still plays a major role today in the detection of a hearing loss deficiency. It remains the easiest hearing screening examination the otologist can perform almost anytime with no side effects. We have successfully understood the key roles the Rinne test plays in the identification of some major causes of hearing deficiencies. It is important to take note that the Rinne test and the Weber test are performed together in most cases for a more accurate result.
Rinne test, on the other hand, should be regarded as a quick way of scanning for hearing deficiency. It is not designed to replace formal auditory test. The validity of this test is sometimes questioned. Therefore, this test needs to be performed with caution by professional and must be regarded as only a screening test.
We have understood that one of the limitations to this test is in the cases of severe unilateral hearing loss. It becomes difficult for the Rinne test to identify the difference between the sensorineural and the conductive hearing loss.
Notwithstanding, the Rinne and Weber test remains an important part of medical hearing aid screening.