A text-book of the diseases of the ear and adjacent organs . edinger has the hammer moved by clock- * As Oscar Wolf quite correctly remark atch is not a noise, but a sound having a distinct pitch. TESTING THE ACUTENESS OF HEARING FOR SIMPLE TONES. 129 work; Burckhardt-Merian, after the method of NefFs hammer, has it raisedby an electric curreiit. At the superior and inferior extremities of thecolumn are two flat semicircles (6, a), by which two fingers may grasp theinstrument, the superior semicircle for the forefinger and the inferior for thethumb. Below the superior semicircle, parallel with
A text-book of the diseases of the ear and adjacent organs . edinger has the hammer moved by clock- * As Oscar Wolf quite correctly remark atch is not a noise, but a sound having a distinct pitch. TESTING THE ACUTENESS OF HEARING FOR SIMPLE TONES. 129 work; Burckhardt-Merian, after the method of NefFs hammer, has it raisedby an electric curreiit. At the superior and inferior extremities of thecolumn are two flat semicircles (6, a), by which two fingers may grasp theinstrument, the superior semicircle for the forefinger and the inferior for thethumb. Below the superior semicircle, parallel with the axis of the per-cussion-hammer, there is a ring on the vulcanite column, into which a pin,having a round metal plate attached (i), can be inserted. This last con-trivance is for testing the perception of the cranial bones by bringing themetal plate into contact with the temple or with the mastoid process whilethe meatuses are closed. In the same manner, in cases where the tone ofthe acoumeter is not heard even on the closest proximity, the round metal. Fig. 83.—The Universal Acoumeter designed by the Author. plate is brought into contact with the orifice of the external meatus, to findwhether the tone of the acoumeter is perceived by contact. The cylinder is tuned to c and gives the sound of a loudly-ticking exact tuning of the cylinder is produced bj7 boring out, and its tone isindicated by blowing into the mouth of the cylinder. It is evident that theinstrument, as a universal acoumeter, will only fulfil its object if all the partsin every instrument are exactly alike and each instrument exactly more severe deafness, where the acoumeter is not heard, I often use themetronome. While testing the hearing with the acoumeter, just as with thewatch, the direction of the instrument to the external orifice of theear must be considered, as the acuteness of hearing is materiallymodified by the position of the origin of sound to the ear. As arule, the tone will
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Keywords: ., bookcentury1800, bookdecade1890, booksubjecteardiseases, bookyear
