432 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



Arrangements for Changing the Pitch of the Voice. — As has frequently 

 been mentioned, the vocal cords are stretched, and the pilch of their note is 

 elevated, by contraction of the crico-thyroid muscle. But the change that is 

 thus produced in the tension of the vocal cords is by no means capable of 

 accounting for the full range of pitch which falls within the compass of the 

 voice. When the arytenoid and the crico-arytenoid muscles sufficiently. con- 

 tract, the vocal processes are brought tightly together and their vibration is 

 prevented. Voice-production must then be limited to the vocal cords them- 

 selves, and the stretching action of the crico-thyroids may begin anew and 

 reach its maximum with the glottis so set that only it.- ligamentous borders can 

 vibrate. It can also be seen that the vocal cords themselves may be shortened 

 functionally, or even be broken up into segments, or the main body of the cord 

 be changed in thickness, by contraction of the complex thyro-arytenoid muscles; 

 each such condition would be accompanied by a change in the rate of vibra- 

 tion. We are probably justified in assuming that, when the musical scale is 

 sung, the lowest notes are produced by vibration of the glottic borders through- 

 out their full length, and the elevation of pitch is affected by the gradually- 

 increased tension of the vocal ligaments through the action of the crico-thyroid 

 muscle. This contraction having reached its maximum, the muscle probably 

 relaxes, only to contract again after the vibrating segments of the glottis are 

 shortened by a partial or complete clamping together of the vocal processes 

 in the manner described above. There are thus two or three, or more, 

 adjustments which may be imparted to the vibrating mechanism of the lar- 

 ynx, each of which is distinguished by giving rise to a note of different 

 pitch that may further be altered by action of the crico-thyroid muscle. 

 It might be anticipated that the voice whose pitch was gradually ele- 

 vated in the manner described would suffer some alteration in quality 

 at those points in the scale where there is a change in the set of the lar- 

 vnx producing a shortening of the vibrating segment. Such, indeed, is 

 the fact. 



Registers. — Long before the invention of the laryngoscope, and before any- 

 thing definite was known of the method of voice-production, it was recognized 

 that in ascending the musical scale there occur certain breaks, as it were, where 

 the voice changes in quality as well as in pitch. It is an object in musical 

 education to render these breaks as little prominent as possible. The kinds of 

 voice included between these breaks were distinguished as the vocal " registers." 

 There is no general agreement among musicians as to how many registers are 

 compassed by the voice, and the nomenclatures used to distinguish them differ 

 in the most confusing fashion. According to some authors, the range of the 

 voice is included within two registers only; more commonly three distinct 

 registers are described, to which, in certain cases, a fourth is said to be prob- 

 able added. The most common designation of the lowesl register is the "chest 

 voice," though it has also been called "thick" 1 as distinguished from the 

 " thin " register; another term applied to it is the " long-reed " register as con- 

 1 Browne and Behnke : Voice, Song, and Speech, 1890, p. 135. 



