490 MANUAL OF PHYSIOLOGY. 



choosing for their telling crescendo some note high up in the range 

 of their voice. 



The human voice, including all kinds of voice, extends over 

 about three and a half octaves. Of this wide range a single in- 

 dividual can seldom sing more than two octaves. The soprano, 

 alto, tenor, and bass form a descending series, the range of each 

 one of which considerably overlaps the next in the scale. 



During the ordinary vocal sounds, the air, both in the resonat- 

 ing tubes above the larynx and in the windpipes coming from 

 below, is set vibrating, so that the trachea and bronchi act as 

 resonators as well as the pharynx, mouth, etc. This may be rec- 

 ognized by placing the hand on the thorax, when a distinct 

 vibration is communicated from the chest-wall. Such tones are, 

 therefore, spoken of as chest notes. Besides the chest tones of 

 the ordinary voice, we can produce notes of a higher pitch and 

 a different quality, which are called head notes, since their pro- 

 duction is not accompanied by any vibration of the chest- wall. 

 The physical contrivance by means of which this falsetto voice is 

 brought about is not very clearly made out. The following are 

 the more probable views: (1) It has been suggested that in 

 falsetto only the thin edges of the cords vibrate, the internal 

 thyro-arytenoid muscles keeping the base of the cord fixed ; while 

 with chest tones a greater surface of the cord is brought into 

 play. (2) The cords are said to be wider apart in falsetto than 

 in chest notes, and hence the trachea, etc., ceases to act as a reso- 

 nator. (3) Or the cords may be arranged so that only one part 

 of them, the anterior, can vibrate, and thus they act as shortened 

 cords, a " stop " being placed on the point where the vibrations 

 cease, by the internal thyro-arytenoid muscle. 



The production of a falsetto voice is distinctly voluntary, and 

 is probably dependent upon some muscular action in immediate 

 relation to the cords, for it is always associated with a sensation 

 of muscular exertion in the larynx as well as with changes that 

 take place in the conformation of the mouth and other resonat- 

 ing tubes. 



