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The Weber test is a quick screening test for hearing. It can detect unilateral (one-sided) conductive hearing loss (middle ear hearing loss) and unilateral sensorineural hearing loss (inner ear hearing loss). The test is named after Ernst Heinrich Weber (1795–1878). Conductive hearing ability is mediated by the middle ear composed of the ossicles: incus, malleus, 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 test has had its value as a screening test questioned in the literature. ==Weber test performance== The Weber and the Rinne test ( ) 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 〔http://www.ncbi.nlm.nih.gov/books/NBK231/〕 or 512 Hz 〔http://american-hearing.org/disorders/hearing-testing/〕 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 equi-distant 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. In an affected patient, if the normal ear hears the tuning fork sound better, there is sensorineural hearing loss on the other (defective) ear. However, the aforegoing presumes one knows in advance which ear is defective and which is normal (such as the patient telling the clinician that they cannot hear as well in one ear versus the other) and 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. That is, an abnormal Weber test is only able to tell the clinician that there is a conductive loss in the ear which hears better or that there is a sensorineural loss in the ear which does not hear as well. 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, the fork is then immediately 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 the sound heard outside the ear (air conduction or AC) is louder than the initial sound heard when the tuning fork end is placed against the skin on top of the mastoid process behind the ear (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. In a normal patient, the Weber tuning fork sound is heard equally loudly in both ears, with no one ear hearing the sound louder than the other (lateralization). Similarly, a patient with symmetrical hearing loss will hear the Weber tuning fork sound equally well, with diagnostic utility only in asymmetric (one-sided) hearing losses. In a patient with hearing loss, the Weber tuning fork sound is heard louder in one ear (lateralization) than the other. This clinical finding should be confirmed by repeating the procedure and having the patient occlude one ear with a finger; the sound should be heard best in the occluded ear. The results of both tests are noted and compared accordingly below to localize and characterize the nature of any detected hearing losses. Note: the Weber and Rinne are screening tests that are not replacements for formal audiometry hearing tests. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Weber test」の詳細全文を読む スポンサード リンク
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