the Physiology of the Human Voice. 345 



both by analogy and by experiment, which, I conceive, af- 

 ford demonstrative proof of the truth of the theory novi^ ad- 

 vanced, and completely refute those to which reference has 

 previously been made *. 



First. The vibrations of the glottis are the fundamental 

 cause of all the tones of the human voice. 



Secondly. The vibrating length of the glottis depends con- 

 jointly on the tension and resistance of the vocal ligaments, 

 and on the pressure of the column of air in the trachea. 



Thirdly. The grave tones vary directly and the acute tones 

 inversely as the vibrating length and tension of the vocal li- 

 gaments. 



Fourthly. The vocal tube is adjusted to vibrate with the 

 glottis, by the combined influence of its variations of length 

 and of tension. 



Fifthly. The elevation of the larynx shortens the vocal 

 tube, and its depression produces the contrary effect. The 

 diameter and tension of the tube vary reciprocally with the 

 length. 



Sixthly. The falsetto tones are produced by a nodal divi- 

 sion of the column of air, together with the vocal tube, into 

 separate vibrating lengths. 



Seventhly. The pitch of the vocal organs, when in a state 

 of rest, is in general the octave of their fundamental note. 



In conclusion, it may be remarked that the physiology of 

 the human voice cannot fail to be a subject of interest to every 

 inquiring mind, and many whose names shed a lustre on sci- 

 ence have devoted a considerable portion of their time to its 

 investigation. The advantages resulting from the study of 

 the voice not only tend to enlarge the sphere of natural know- 

 ledge, but also, in a medical point of view, serve as a basis for 

 diagnostic, therapeutic, and pathological inquiry, and conse- 

 quently contribute to the general benefit of mankind. 



Animals far inferior in their organization and intellect to 

 man, are endowed with the power of uttering tones sufficient 

 for the sphere of their existence. The roar of the lion, the 

 lowing of the ox, the song of birds, and the hiss of serpents 

 constitute a natural language which adequately expresses their 

 wants and their passions, and is sufficient for the degree of 

 intelligence belonging to the rank which they occupy in the 

 scale of animal organization. 



• The hypotheses of Aristotle and Dodart respecting the size of the 

 chink of the glottis must necessarily place the thyro-arytenoidean liga- 

 ments out of the vibrating position : the same objection applies to that of 

 Ferrein. The theory of tension re(|uires the glottis to be always open, and 

 vibrating in its whole length, to produce every tone of the vocal scale, a 

 supposition which is opposed both by observation and by experiment. 

 Third Series. Vol.9. No. 55. Nov. 183G. 2 S 



