V 



THE SENSE OF HEARING 



259 



more, clearly and acutely than those transmitted by bone- conduction. To 

 tins experiment it may be objected that I he note of the prongs and that 

 of the stem of a tuning-fork are not comparable, so that the tone of the stem 



only should lie used. 



Schwabach's experiment is based on thr observation that when trans- 

 mission of the sound-waves in the ordinary way is obstructed, the fork 

 applied to the bone is heard somewhat longer than normally only of course 



I i. . 105. To show tin 1 Chanel's in the nptieal imam's nf tin 1 vibrations of a tuiiin^-tbrk with 

 'lual ilirri'iisi- in tin 1 aiii]plituili- uf tin 1 vilu at inns. (I iiaili'iiigo.) 



wlii-n tin- organ of Corti functions properly ; if this be also diseased, the tone 

 transmitted by the bones is heard with difficulty or not at all. 



In Gelld's experiment air is blown artificially against the external 

 auditory passage after tin- im-atus has been hermetically sealed, until bone- 

 condnction ,,!' the tones becomes weakened, owing probably to the pressure 

 exerted 0:1 tin- organ of Corti by the tension of the tympanic membrane and 

 tin- i-hain of ossicl. -. If the perception of sound thus conveyed through the 

 bones is not weakened, it may be concluded that the articulation of the chain 

 of ossicles (stapes) is anchylosed. 



