THE PRODUCTION OP THE VOICE. 205 



tions closely resembling those of a rigid tongue with an attached tube. Length- 

 ening of the tube causes the pitch to fall by semitones, but it does not sink a 

 whole octave, as happens with rigid tongues. When a wind-tube is added to 

 a tongue, the effects produced on the pitch, by lengthening it, are similar to 

 those produced by increasing the length of the attached tube. Diminution of 

 the calibre of that part of the wind-tube nearest to the tongue, heightens the 

 pitch of the note. Partial covering of the end of the attached tube, causes a 

 lowering of the pitch. 



The Production and Characters of the Human Voice. 



The researches and observations of physiologists have long since 

 proved that the sounds of the voice in man and mammalia are produced 

 by the vibratory action of the vocal cords, during the passage of the 

 air through the glottis ; and that these cords vibrate according to the 

 laws which regulate the vibration of stretched membranous tongues. 

 Experiments on living animals show that the vocal cords are alone 

 the essential organs for the production of voice, for so long as these 

 remain untouched, although all the other parts in the interior of the 

 larynx be destroyed, the animal is able to emit vocal sounds. Diseases 

 of the larynx in man produce similar results. Again, if all the struc- 

 tures of the larynx of a dead animal, except the vocal cords, be re- 

 moved, and these be rendered tense and approximated, vocal sounds 

 can be generated by forcing currents of air through the glottis from 

 below. If the h^uman larynx be removed from the body, and currents 

 of air be made to pass, from its lower end, through the glottis, sounds 

 are also produced. By making an opening in the larynx of a living 

 animal, so as to expose the vocal cords, the vibrations of these may 

 be distinctly seen during the emission of vocal sounds. The existence 

 of an opening in the larynx of a living animal, or of man, above the 

 glottis, in no way prevents the formation of vocal sounds ; such an 

 opening, if situated in the trachea, causes total loss of voice, but by 

 simply closing it, vocal sounds can again be produced. Sucji open- 

 ings, in man, are met with, either as the results of accidents, of suicidal 

 attempts, or of operations performed on the larynx or trachea, for the 

 relief of disease. Division or injury of the laryngeal nerves, at once 

 destroys voice, the muscles which regulate the tension of the vocal 

 cords being then paralyzed. Lastly, by means of the laryngeal mir- 

 ror, or laryngoscope, of M. Garcia, the vocal cords can be seen to 

 vibrate during vocalization. The laryngoscope consists essentially of 

 a small flat metallic mirror provided with a long handle; being intro- 

 duced into the pharynx through the open mouth, it is made to re- 

 ceive rays of light from the sun, or from a lamp, thrown upon it by 

 means of another large and concave mirror placed in front of the 

 mouth ; the small mirror is held with its surface at such an angle that 

 the rays of light are thrown down from it upon the laryngeal opening, 

 and so illuminate it. But the light reflected back from the larynx on 

 to the small mirror produces on its surface an image of the parts, which 

 image is, of course, again reflected towards the larger mirror. In. the 

 centre of the latter is a small aperture, behind which the observer 

 places his eye, and, in this manner, some of the rays are intercepted 

 by the eye, and a laryngeal picture is visible. By means of this in- 



