548 HANDBOOK OF PHYSIOLOGY. 



be produced only with the natural voice, the highest with the falsetto 

 only; the notes of middle pitch can be produced either with the natural 

 or falsetto voice; the two registers of the voice are therefore not limited 

 in such a manner as that one ends when the other begins, but they run 

 in part side by side. 



The natural or chest-notes are, as we have seen, produced by the or- 

 dinary vibrations of the vocal cords. The mode of production of the 

 falsetto notes is still obscure. 



By Miiller they were thought to be due to vibrations of only the inner 

 borders of the vocal cords. In the opinion of Petrequin and Diday, they 

 do not result from vibrations of the vocal cords at all, but from vibra- 

 tions of the air passing through the aperture of the glottis, which thev 

 believe assumes, at such times, the contour of the embouchure of a flute. 

 Others, considering some degree of similarity which exists between the 

 falsetto notes and the peculiar tones called harmonic, which are pro- 

 duced when, by touching or stopping a harp-string at a particular point, 

 only a portion of its length is allowed to vibrate, have supposed that, in 

 the falsetto notes, portions of the cords are thus isolated, and made to 

 vibrate while the rest are held still. The question cannot yet be settled; 

 but any one in the habit of singing may assure himself, both by the 

 difficulty of passing smoothly from one set of notes to the other, and by 

 the necessity of exercising himself in both registers, lest he should 

 become very deficient in one, that there must be some great difference 

 in the modes in which their respective notes are produced. 



The pitch of the note, which depends upon the rapidity of the vibra- 

 tions, is altered by alterations of the vocal cords, and so the strength of 

 the voice is in proportion (a) to the degree to which the vocal cords can 

 be made to vibrate; and partly (b) to the fitness for resonance of the 

 membranes and cartilages of the larynx, of the parietes of the thorax, 

 lungs, and cavities of the mouth, nostrils, and communicating sinuses. 

 It is diminished by anything which interferes with such capability of 

 vibration. 



The intensity or loudness of a given note with maintenance of the 

 same pitch, cannot be rendered greater by merely increasing the force 

 of the current of air through the glottis; for increase of the force of the 

 current of air, cceteris parib-us, raises the pitch both of the natural and 

 the falsetto notes. Yet, since a singer possesses the power of increasing 

 the loudness of a note from the faintest piano iQ fortissimo without its 

 pitch being altered, there must be some means of compensating the 

 tendency of the vocal cords to emit a higher note when the force of the 

 current of air is increased. This means evidently consists in modify- 

 ing the tension of the vocal cords. When a note is rendered louder 

 and more intense, the vocal cords must be relaxed by remission of the 



