Hearing loss, known as hypacusis in technical jargon, refers to a limitation of hearing. It affects more and more people and can range from mild impairment to complete hearing loss. Some symptoms are only noticeable for a certain time, others are permanent. Hearing loss can have many causes. Often it comes with the age of the patient or as a result of a disease or noise exposure. In some cases, hearing loss is also inherited. A simple and quick tentative diagnosis can be made using the tools available in the family doctor’s office. Various tuning fork tests, for example, give the doctor reliable indications as to which part of the ear could be causing a hearing disorder. These tests using tuning forks include the Weber test.
What is the Weber test?
A tuning fork test that is used in doctors’ offices on a daily basis because of its uncomplicated method of application is the Weber test. A tuning fork test that is used daily in doctors’ offices because of its uncomplicated method of application is the Weber experiment. It is named after Ernst Heinrich Weber. As a professor of anatomy and physiology in Leipzig, he drew attention to this method as early as 1834. As a standard test in ear, nose and throat medicine for examining a hearing disorder, this method can be used to quickly and effectively isolate possible causes of hearing loss. Hearing loss can be caused by disorders in the external auditory canal, in the middle or inner ear, but also centrally in the auditory pathway. Depending on the place of origin of the disorder, hearing loss is divided into sound perception disorder (damage in the inner ear or auditory nerve area) and sound conduction disorder (impairment in the middle ear or external auditory canal). The extent of a hearing impairment can range from a slight hearing loss to deafness. The Weber test allows a good diagnosis of unilateral hearing loss and is particularly suitable for differentiating conductive and sensorineural hearing loss. The examination is an uncomplicated and painless procedure and belongs to the so-called subjective test procedures, since it depends on the active cooperation of the patient. In most cases, the Weber test helps to determine from which part of the ear a hearing disorder is caused. For this clinically orienting hearing test, the physician uses a tuning fork.
Function, effect and goals
With the help of the tuning fork, the physician is able to identify and localize different hearing problems. This method is based on Mach’s sound conduction theory: in conductive hearing loss, if the propagation of sound through the ossicular chain is disturbed, the sound arriving at the middle ear via bone conduction remains trapped there and is not transmitted. For diagnosis, the doctor uses the same tuning fork as a musician uses to tune his instrument. It vibrates in the concert pitch a at 440 hertz. The doctor can use it to examine whether a tone produced with the tuning fork is transmitted through the head bones and perceived by the patient. The tuning fork is set in vibration and placed on the crown of the patient’s head with the foot. The sound is then transmitted to the inner ears via the bone conduction. If there is nothing wrong with the hearing, the vibrations of the tuning fork are registered equally in both ears. If there is a problem, the sound appears louder in one ear than in the other. In this way, disturbances in the air conduction can be identified, for example a narrowing of the ear canal or a loss of intensity in the middle ear. In this case, the affected person reports hearing the sound particularly loudly for the ear with which he or she hears less well. This phenomenon is easy to understand: If you cover one ear, you hear your own spoken word particularly loudly in that ear. Through its correct interpretation, the Weber test allows an orienting classification of the type of hearing loss. A normal hearing patient or a patient with equal hearing loss hears the tone of the tuning fork with both ears equally loud after placing it on the skull. The patient with normal hearing also registers the tone of the tuning fork as the same in both ears. He therefore has the impression of hearing it in the middle of the head. The sound is not lateralized, that is, it is not directed to one side. If the patient states that he hears the tone on one side, it is called lateralization. In this case, there is a unilateral or asymmetric hearing disorder.In the case of a unilateral sound perception disorder, the sound is perceived louder by the better hearing inner ear, so the patient lateralizes to the healthy ear. However, in unilateral conductive hearing loss, the sound is heard louder in the affected ear, usually to the patient’s amazement. Conductive hearing loss is when sound is not transmitted in the outer or middle ear. This can be caused by earwax or a middle ear infection. If there is a conductive hearing loss, the sound is perceived louder in the affected ear. In the case of sensorineural hearing loss, the sound is better received in the unaffected ear. Sensorineural hearing loss can be caused by damage to the inner ear, auditory nerve or brain. The diagnosis in this case may be acute hearing loss, Meniere’s disease (disease of the inner ear), damage to the inner ear or auditory nerve, acoustic neuroma (a benign tumor on the vestibular and auditory nerves)or traumatic injury from a skull base fracture. Often, acute sensorineural hearing loss can also be triggered in the setting of a blast trauma or develop without known causes. The most common trigger for conductive hearing loss is a ceruminal plug, or earwax. Leading symptoms are an acute hearing loss accompanied by a feeling of pressure to ear pain.
Risks, side effects and dangers
In the case of lateralization in the Weber test, the doctor will follow up with another tuning fork test, the Rinne test. This allows the cause of hearing loss to be further narrowed and more accurately determined. Tuning fork testing is safe for health.