The Weber test is a screening test for hearing performed with a tuning fork. It can detect unilateral (one-sided) conductive hearing loss (middle ear hearing loss) and unilateral sensorineural hearing loss (inner ear hearing loss) Conductive hearing ability is mediated by the middle ear composed of the ossicles: the malleus, the incus, and the stapes. Sensorineural hearing ability is mediated by the inner ear composed of the cochlea with its internal basilar membrane and attached cochlear nerve (cranial nerve VIII). The outer ear consisting of the pinna, ear canal, and ear drum or tympanic membrane transmits sounds to the middle ear but does not contribute to the conduction or sensorineural hearing ability save for hearing transmissions limited by cerumen impaction (wax collection in the ear canal).
The Weber and the Rinne test are typically performed together with the results of each combined to determine the location and nature of any hearing losses detected. In the Weber test a vibrating tuning fork (Typically 256 Hz or 512 Hz used for Weber vibration test; 512 Hz used for Rinne hearing test) is placed in the middle of the forehead, above the upper lip under the nose over the teeth, or on top of the head equidistant from the patient's ears on top of thin skin in contact with the bone. The patient is asked to report in which ear the sound is heard louder. A normal Weber test has a patient reporting the sound heard equally in both sides. In an affected patient, if the defective ear hears the Weber tuning fork louder, the finding indicates a conductive hearing loss in the defective ear. Also in the affected patient, if the normal ear hears the tuning fork sound better, there is sensorineural hearing loss on the other (defective) ear. However, this assumes that it is known which ear is defective and which is normal (e.g. by the patient telling the clinician that they cannot hear as well in one ear as in the other), with the testing is being done to characterize the type, conductive or sensorineural, of hearing loss that is occurring. In the case where the patient is unaware or has acclimated to their hearing loss, the clinician has to use the Rinne test in conjunction with the Weber to characterize and localize any deficits.
For the Rinne test, a vibrating tuning fork (typically 512 Hz) is placed initially on the mastoid process behind each ear until sound is no longer heard. Then, without re-striking the fork, the fork is then quickly placed just outside the ear with the patient asked to report when the sound caused by the vibration is no longer heard. A normal or positive Rinne test is when sound is still heard when the tuning fork is moved to air near the ear (air conduction or AC), indicating that AC is equal or greater than (bone conduction or BC). Therefore, AC > BC; which is how it is reported clinically for a normal or positive Rinne result. In conductive hearing loss, bone conduction is better than air or BC > AC, a negative Rinne, and the patient will report that they do not hear the fork once it is moved. The Rinne test is not ideal for distinguishing sensorineural hearing loss, as both sensorineural hearing loss and normal hearing report a positive Rinne test (though the sensorineural patient will have a decreased duration of hearing sound once the fork is moved to air).