LYUSHERA TEST (E. Luscher, sovr, the Swiss otorhinolaryngologist) — differential (or differential) a threshold of perception of sound intensity, under the Crimea the minimum decrease or increase in intensity of a sound causing change of its loudness mean a method of determination of size. The Differential Threshold (DT) depends on the frequency of a sound and its superthreshold intensity. Normal at intensity of a sound in 40 dB over a hearing threshold of DP it is equal to 8 — 16% that there correspond 0,9 — 1,5 dB.
The method of definition of DP thanks to simplicity and availability of performance was widely used in a wedge. to practice. Measurement of DP is performed by the audiometer supplied with the modulator of amplitude, and the potentiometer allowing gradually 2 — 4 times in 1 sec. to increase amplitude of modulation of a sound from 0,2 to 6 dB at superthreshold intensity of tone 40 dB. At substantial increase of thresholds of hearing superthreshold intensity can be 20 dB.
Strict parallelism between the size DP and a phenomenon of acceleration of increase of loudness — a symptom, pathognomonic for defeat of the receptor device of a snail and the shown inadequately strong acoustical feeling is noted at small increase in intensity of a sound. Decrease in DP is observed at the changed function of the sound perceiving device and demonstrates existence of a phenomenon of acceleration of increase of loudness.
Lyusher in size DP allocates three groups of dysfunctions of the acoustic analyzer: defeat of sensory cells of spiral body with the lowered DP — 6 — 8% and less, a retro labyrinth organic lesions with normal DP — 8 — 16% and psychogenic disturbances with the raised DP — 16-20%.
Differential and diagnostic value L. the item has only in combination with data of tone threshold audiometriya (see). It is necessary to investigate separately each ear that is important at bilateral defeat.
Bibliography: Relative deafness, under the editorship of N. A. Preobrazhensky, M., 1978; Undrits V. F., Temkin Ya. S. and Neymanl.V. Guide to a clinical audiology, M., 1962, bibliogr.; Luscher E. Difference limen of intensity variations of pure tones and its diagnostic significance, J. La-ryng., v. 65, p. 486, 1951; Luscher E. Zwislocki J. Simple method for indirect monaural determination of recruitment phenomenon, Acta oto-laryng. (Stockh.), suppl., v. 78, p. 156, 1949.
I. B. Soldatov.