342 VOCAL APPARATUS. L.ECT. XVIII. 



The apparatus with membranous reeds constitutes the 

 largest number of wind instruments ; and we must include 

 among them the trumpet and French horn. Indeed, an 

 experienced performer embraces three octaves by merely 

 varying the tension of his lips, without modifying the length 

 of the column of air. 



The Human Vocal Organ is a Reed Instrument. I believe 

 that these introductory observations respecting membranous 

 reeds, will enable you to form a clear notion of the pro- 

 duction of the human voice. The organ is essentially a 

 reed-apparatus, formed by two membranous lips. 



Mullens Experiments. The experiment of Miiller, which 

 I am about to quote, will render this conclusion evident : 

 He fixed the larynx of a human subject upon a board, 

 after having removed all the parts above the inferior liga- 

 ments. Then, by means of a hook, he attached a thin 

 cord to the angle of the thyroid cartilage, immediately 

 above the vocal cords. The string passed over a pulley, 

 and was connected with a scale, loaded with weights. By 

 employing different weights, the cartilage was pulled, and 

 the vocal cords stretched. A wooden tube was introduced 

 into the trachea, to blow through. The following are the 

 principal results which Miiller obtained with this appara- 

 tus : 



1st. When the glottis was sufficiently narrowed, and the 

 inferior ligaments stretched, he obtained clear and full 

 tones, which approximated to those of the human voice. 

 An artificial larynx, made either with bands of the mid- 

 dle coat of arteries, or with caoutchouc, yields similar re- 

 sults. 



2d. By altering the tension of the vocal cords, the notes 

 rise with the tension to an extent of about two octaves ; 

 and when the tension is very considerable, the sounds be- 

 come disagreeable and whistling. 



