﻿On the Falsetto or Head-sounds of the Human Voice. 289 



tion my objection as well. Should the experimental test decide 

 against me, I will willingly retract my calculations, the more 

 so because they are only approximately correct. This may be 

 brought about either by the new experiments of Messrs. Stewart 

 and Tait, or by Sir William Thomson's promised determination 

 of the radiation of heat in absolute measure. But so long as this 

 experimental test is wanting it would be idle to continue a dis- 

 pute about an unproved hypothesis. 

 Breslau, February 13, 1869. 



XXXIX. On the Falsetto or Head- Sounds of the Human Voice. By 

 William Marcet, M.D., F.R.S., Assistant Physician to the 

 Hospital for Consumption and Diseases of the Chest, Brompton*. 



THE consideration of the cause of the head-notes of the 

 human voice is of much interest, not only in a physiolo- 

 gical point of view, with the object of accounting for the produc- 

 tion of those wonderfully soft and penetrating sounds in which 

 Swiss and Tyrolese singers are so remarkably proficient, but also 

 for the purpose of explaining certain morbid changes of the hu- 

 man voice not unfrequently met with. Let me premise that, by 

 means of the laryngoscope (a small mirror so constructed as to 

 allow the observer to view the inside of the larynx and the action 

 of its various parts in the production of sound), the phenomenon 

 of phonation can be investigated with great minuteness. There 

 are, moreover, certain changes of form the larynx undergoes in 

 the act of phonation, and bearing on the subject of the present 

 communication, which can be determined by external observa- 

 tion, much in the same way as we can ascertain by looking and 

 feeling, that the windpipe is raised in the act of swallowing. 



The vocal apparatus consists of two folds of the mucous mem- 

 brane of the larynx, supplied at their free edge with bands of 

 elastic tissue. These folds are opposite each other in a horizontal 

 plane, and in the an tero- posterior axis of the larynx. Their lips 

 or free edges may be brought so close as to touch one another, 

 while at the same time they may be subjected to a certain degree 

 of tension ; if under these circumstances air be blown out from 

 the lungs, these laryngeal folds or vocal cords will be made to vi- 

 brate, emitting a sound. 



It is considered by J. Muller and others that the human chest- 

 sounds are owing to the whole breadth of the laryngeal mem- 

 branes entering into vibration, while the head-sounds are due 

 to the vibrations being confined to the margins or mere edges 

 of the membranes. Helmholtz thinks the head-sounds are caused 



* Communicated by the Author. 

 Phil Mag. S. 4. Vol. 37. No. 249. April 1869. U 



