56 HAND-BOOK OF PHYSIOLOGY. 



The degree of approximation of the vocal cords also usually corre- 

 sponds with the height of the note produced; but probably not always, for 

 the width of the aperture has no essential influence on the height of the 

 note, as long as the vocal cords have the same tension: only with a wide 

 aperture, the tone is more difficult to produce, and is less perfect, the 

 rushing of the air through the aperture being heard at the same time. 



No true vocal sound is produced at the posterior part of the aperture 

 of the glottis, that, viz., which is formed by the space between the aryte- 



FIG. 300. FIG. 301. 



FIG. 300. View of the anterior of larynx from above. 1, aperture of glottis; 2, arytenoid car- 

 tilages; 3, vocal cords; 4, posterior crico-arytenoid muscles; 5, lateral crico-arytenoid muscle of right 

 side, that of left side removed ; 6, arytenoid muscle ; 7, thyro-ary tenoid muscle of left side, that of 

 right side removed; 8, thyroid cartilage; 9, cricoid cartilage; 13, posterior crico-arytenoid ligament. 

 (Willis.) 



FIG. 301. View of the upper part of the larynx as seen by means of the laryngoscope during the 

 utterance of a grave note, c, epiglottis; s, tubercles of the cartilages of Santorini; a, arytenoid car- 

 tilages; z, base of the tongue; hph, the posterior wall of the pharynx. (Czermak.) 



noid cartilages. For, as Muller's experiments showed, if the arytenoid 

 cartilages be approximated in such a manner that their anterior processes 

 touch each other, but yet leave an opening behind them as well as in 

 front, no second vocal tone is produced by the passage of the air through 

 the posterior opening, but merely a rustling or bubbling sound; and the 

 height or pitch of the note produced is the same whether the posterior 

 part of the glottis be open or not, provided the vocal cords maintain the 

 same degree of tension. 



APPLICATION OF THE VOICE IN SINGING AND SPEAKING. 



Varieties of Vocal Sounds. The notes of the voice thus produced 

 may observe three different kinds of sequence. The first is the monoto- 

 nous, in which the notes have nearly all the same pitch as in ordinary 

 speaking; the variety of the sounds of speech being due to articulation in 

 the mouth. In speaking, however, occasional syllables generally receive a 

 higher intonation for the sake of accent. The second mode of sequence 

 is the successive transition from high to low notes, and vice versa, with- 

 out intervals; such as is heard in the sounds, which, as expressions of 



