498 THE HUMAN BODY 



per 1") to d" (297 vib. per 1"); and a soprano from b' (248 vib. 

 per 1") to g" f (792). 



Vowels are, primarily, compound musical tones produced in 

 the larynx. Accompanying the primary partial of each, which 

 determines its pitch when said or sung, are a number of upper 

 partials, the first five or six being recognizable in good full voices. 

 Certain of these upper partials are reinforced in the mouth to 

 produce one vowel, and others for other vowels; so that the va- 

 rious vowel sounds are really musical notes differing from one an- 

 other in timbre. The mouth and throat cavities form an air- 

 chamber above the larnyx, and this has a note of its own which 

 varies with its size and form, as may be observed by opening the 

 mouth widely, with the lips retracted and the cheeks tense; then 

 gradually closing it and protruding the lips, meanwhile tapping 

 the cheek. As the mouth changes its form the note produced 

 changes, tending in general to pass from a higher to a lower pitch 

 and suggesting to the ear at the same time a change from the 

 sound of a (father) through o (more) to oo (moor). When the 

 mouth and throat chambers are so arranged that the air in them 

 has a vibratory rate in unison with any partial in the laryngeal 

 tone, it will be set in sympathetic vibration, that partial will be 

 strengthened, and the vowel characterized by it uttered. As the 

 mouth alters its form, although the same note be still sung, the 

 vowel changes. In the above series (a, o, oo) the tongue is de- 

 pressed and the cavity forms one chamber; for a this has a wide 

 mouth opening ; for o it is narrowed ; for oo still more narrowed, 

 and the lips protruded so as to increase the length of the resonance 

 chamber. The partial tones reinforced in each case are, accord- 

 ing to Helmholtz 



In other cases the mouth and throat cavity is partially subdi- 

 vided, by elevating the tongue, into a wide posterior and a nar- 

 row anterior part, each of which has its own note ; and the vowels 

 thus produced owe their character to two reinforced partials. 



