Weber attempt
The Weber experiment is an examination to determine lateralization of the hearing sensation using a tuning fork . Together with the Rinne test, it is a standard test in ear, nose and throat medicine for examining a hearing impairment .
In the Weber experiment, the foot of a vibrating tuning fork is placed on the head of the subject. The sound is transmitted in phase to both inner ears via bone conduction . The person with normal hearing hears the tone of the tuning fork in both ears, so he has the impression of hearing it in the middle of the head, the tone is not lateralized (lat. Latus = side). If the test person states that they can hear the sound on one side, this is called "lateralization". This is the case with a unilateral or asymmetrical hearing disorder.
With a one-sided sensorineural disorder , the sound is perceived louder by the better hearing (normal) inner ear, so the patient lateralises into the healthy ear. In the case of a one-sided sound conduction disorder, however, the sound in the affected ear is heard louder, usually to the patient's surprise.
According to Mach 's theory of sound drainage, sound energy from the inner ear is transferred from an intact middle ear via the ossicles to the eardrum and radiated into the air. This part of the sound energy supplied directly to the inner ear by the tuning fork via bone conduction is therefore normally not effective in the inner ear. If the middle ear is not able to transmit the sound correctly ( middle ear hearing loss ), this sound energy remains in the inner ear, the sound is perceived louder in this ear than in the healthy ear on the other side. An alternative explanation is that the sensitivity of the inner ear is compensated for on the side of the sound conduction disturbance.
The Weber experiment therefore allows a good diagnosis of a unilateral hearing impairment. In order to quickly and reliably differentiate between a sound sensation disorder and a sound conduction disorder, for example between a sudden hearing loss and a tympanic effusion , the Rinne experiment is well suited after determining lateralization .
history
The name of the test after Ernst Heinrich Weber (1795–1878), professor of anatomy and physiology in Leipzig, is based on a publication by Weber from 1834. However, Weber actually only described the occlusion effect in the healthy ear, which was before him was described by Charles Wheatstone and was later used in the Bing test . The first description of the lateralization in the pathological ear - also in the case of sensorineural disorders - is likely to come from Eduard Schmalz, hearing and speech doctor in Dresden, (1846). In the second half of the 19th century, the value of the Weber test was questioned even by well-known otologists ( Hermann Schwartze ) or at least put into perspective ( Friedrich Bezold , Adam Politzer ).
For further tuning fork tests see also: Bing test , Gellé test , Rinne test .
Web links
- Weber attempt as a Quicktime film. ( Memento from March 17, 2009 in the Internet Archive )
Individual evidence
- ↑ Ernst Mach : On the theory of the auditory organ . In: Meeting reports of the Academy of Sciences Vienna / Mathematisch-Naturwissenschaftliche Classe, Dept. 2 , Volume 48, 1863, pp. 283-300.
- ^ Ernst Heinrich Weber : De utilitate cochleae in organo auditus . In: Ders .: De pulsu, resorptione, auditu et tactu. Annotationes Anatomicae et Physiologicae . Köhler, Leipzig 1834, pp. 25-44.
- ^ Charles Wheatstone: Experiments in audition . In: Quarterly Journal of Science, Literature and Arts , Vol. 22 (1827), ISSN 0370-2944 .
- ^ Egbert H. Huizing: The Early Descriptions of the So-Called Tuning Fork Tests of Weber and Rinne. I. The "Weber Test" and its First Description by Schmalz . In: ORL. Journal for oto-rhino-laryngology , Vol. 35 (1973), pp. 278-282, ISSN 0301-1569 .
- ↑ Eduard Schmalz: Experiences about the diseases of the hearing and their healing . Teubner, Leipzig 1846, p. 101.
