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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



[vol. 47 



It was now evident that the theory was defective in regard to the 

 glottal tone itself. The first supposition was that the glottal tone 

 might not be independent, but might change its character with every 

 vowel. The glottal lips are soft tissues ; might they not change the 

 manner of vibration according to the resonance of the cavities around 

 them? The reed was discarded and experiments were now made 

 with rubber membranes held in wooden frames. Circular, square, 

 and triangular openings (figures 58, 59, 60) were covered with 



Fig. 58. — Circular rubber 

 glottis. 



Fig. 



-Square rubber 

 glottis. 



Fig. 60. — Triangular rub- 

 ber glottis. 



rubber membranes held at any desired tension; the air pressure 

 caused the edges of the slit in the middle to vibrate. Such a mem- 

 brane may vibrate on each side as a whole, or with any number of 

 nodal lines concentric to the slit. The timbre of the tone of the 

 membrane depends on its manner of vibration. Resonators of wood 

 (hard walls) were introduced at this point, as the water and gelatine 

 resonators were inconvenient for manipulation. These resonators 

 could be used singly, doubly, triply, etc. ; the rubber glottis could be 

 introduced directly above the blast or between two resonators. The 

 experiments were entirely successful. By proper combinations of two 

 resonators of different sizes with the rubber glottis between them, all 

 the vowels could be produced. Any change in the size of one of the 

 resonators resulted in a slightly different shading of the vowel tone. 

 It was possible to look into the opening of the upper resonator and 

 see the rubber glottis. Its manner of vibration could be seen to be 

 different for different resonators. These experiments are a sub- 

 stantiation of the view that the action of the human glottis differs 

 with different vowels ; the reason, however, is, in my opinion, a 

 different one for the human glottis. The glottal lips are not thin 

 membranes like rubber, but masses of flesh ; there is little possibility 

 of their changing their vibrations in response to the reaction of the 

 cavities around them. In my opinion the fibers of the M. vocalis 

 which compose the lips, contract differently for each vowel, and 



