FUNCTION OF THE LABYRINTH IJN THE ACT OF HEARING. 907 



animal's head, and this being connected with a gas-bttrner and they were thus 

 enabled to see characteristic vowel-curves in a rotating mirror. 



If one limb of a Y-shaped tube be fitted into the nostrils, while the second is 

 connected with a gas-fixture, and the third with a burner, every time a vowel 

 is uttered the flame is set into sonorous vibrations, which reproduce exactly the 

 sound of the vowel. If the vowel is given a nasal sound, the flame shoots up high, 

 because the air is forced into the nasal cavity. Such a flame also may be analyzed 

 in the rotating mirror. 



The movements of the membrane may be drawn or photographed by means 

 of a writing lever placed in contact with it. In this way characteristic curves 

 are obtained for each vowel: phonautograph of Hensen, A. Fick, and others, 

 Fig. 328 shows the flame-pictures of the vowels, and under each the corresponding 

 tracing as registered by the phonautograph. 



FUNCTION OF THE LABYRINTH IN THE ACT OF HEARING. 



With respect to the part played by the ear in the appreciation of 

 timbre it may be said that, just as a musical tone can be resolved into its 

 fundamental tone and overtones by means of resonators, so the ear is 

 able to make such an analysis. The ear resolves the complicated wave- 

 motions into their components, which it perceives as separate tones 

 harmonizing with one another. As a result of adequately trained 

 observation the ear can bring these components separately to the notice 

 of consciousness, and it distinguishes as different qualities of sound 

 only different combinations of these simple tone-sensations. This 

 resolution of the complicated vibrations into simple pendulum-like 

 vibrations is a most striking property of the ear. What are the mechan- 

 isms in the ear through which this resolution is effected? If with the 

 dampers raised the vowel-sound A be sung loudly in a certain note 

 (for example b) against the strings of an open piano, all of those strings, 

 and only those strings, are set into vibration that are contained in the 

 vowel-sound. It must, therefore, be assumed that a similarly acting 

 apparatus is present in the ear, which is tuned for certain pitches, and 

 is set into sympathetic vibration when a note is sounded, like the strings 

 of a piano. "If we could connect each string of a piano with a nerve-fiber 

 in such a way that the nerve-fiber would be stimulated and receive an 

 impression every time the string was set in motion, each musical tone 

 that strikes the instrument would, in fact, as is actually the case in the 

 ear, excite a series of sensations, corresponding exactly to the oscillatory 

 vibrations into which the original movement of air could be resolved; 

 and thus the existence of every individual overtone would likewise be per- 

 ceived exactly as it is by the ear. Under these circumstances the percep- 

 tions of the various high tones would devolve upon different nerve-fibers, 

 and, therefore, would occur separately and independently of one 

 another. Now, in fact, the recent discoveries of the microscopists 

 as to the intimate structure of the ear permit the assumption that 

 similar arrangements exist in the ear, such as we have just considered. 

 Thus, the end of each fiber of the auditory nerves is connected with 

 small elastic particles, of which we must assume that they are set in 

 vibration in sympathy with the sound-waves" (v. Helmholtz). 



v. Helmholtz believed formerly that the arches of Corti are the appa- 

 ratus attuned to the individual tones, stimulating the nerve by sym- 

 pathetic vibration; in other words that they represent a sort of keyboard. 

 As, however, amphibians and birds have no arches of Corti, although 

 they are certainly able to hear musical tones, the stretched radial fibers 



