236 THE HUMAN BODY. 



of the vocal cords in the larynx after death, M. Fournie' 

 obtained all the notes comprised between two octaves. 



The ventricles of the larynx are contracted and almost 

 effaced during the emission of the voice; their function seems 

 to be to moisten the vocal cords with a mucous fluid, and 

 to aid in their movements, as well as those of the walls of 

 the vestibule and glottis. 



The superior thyro-arytenoid ligaments adapt the tube 

 formed by the vestibule of the glottis to the sounds emitted 

 by the vocal cords. During the emission of sound their 

 borders are never on the same line as the opening of the 

 glottis; sometimes they approach the vocal cords, sometimes 

 they almost disappear, or, on the contrary, enlarge into the 

 vestibule of the glottis so as almost to fill it. By experiments 

 on the dead subject, M. Fournie has proved that if these 

 ligaments are drawn apart during the emission of a note by 

 the larynx, the sound is lower by one tone; if only one is 

 drawn aside it falls a semitone. The same result is produced 

 in all the notes comprised in an octave. 



The epiglottis descends and nearly closes the superior 

 opening of the larynx in grave sounds, and rises more and 

 more as the sound becomes more acute. In the grave 

 notes the soft palate permits the sounds to pass through 

 the mouth and the nasal fossae, and in proportion as the voice 

 is elevated it rises toward the posterior orifice of the nasal 

 fossae, so as to prevent the echoing of the sound in these 

 cavities. 



The nasal fossae give exit to the air when the disposition 

 of the vocal tube is such, in the formation of certain letters, 

 as more or less to hinder its passage through the mouth. The 

 isthmus of the throat and the mouth have no influence on 

 the note, but they perfect and modify its character. The 

 trachea and bronchia, as well as the vocal tube, resound like 

 a harmonic table, of which each part corresponds to one of 

 the notes of the voice; and lastly, the intensity of the sound 

 is in direct proportion to the force of the impulsion of the 

 air, to the extent of the vocal cords put in vibration, and to 

 their tension. 



Formation of sounds in u> hist ling. The study of the for- 



