390 THE ORGAN OF VOICE. 



The sound of a reed instrument is, in consequence of 

 the great number of overtones, rather harsh. In the 

 case of the reed pipes of the organ, the character of the 

 sound is modified to an important degree by the vibra- 

 tions of the air in the open part of the pipe above the 

 reed. The rate of vibration of the air contained in this 

 part of the pipe depends upon its size and shape, and if 

 this rate agrees with that of the fundamental or any of 

 the higher harmonic tones of the reed, the air is thrown 

 into powerful sympathetic vibrations, and the corres- 

 ponding tone is thus greatly strengthened in comparison 

 with the other tones of the sound. 



36. Tlie Organ of Voice. Vowel Sounds. Flame-Mano- 

 meter. The organs by means of which the human voice 

 is produced resemble a reed organ-pipe with the essen- 

 tial difference that a metal tongue produces only one 

 note of a definite pitch, while the tones of the human 

 voice may be varied in pitch at the will of the speaker. 

 The upper end of the windpipe is formed by a short 

 tubular box, called the larynx, the framework of which 

 is formed by a number of cartilages more or less move- 

 able on each other and connected together by joints, 

 membranes, and muscles. Across the middle of the 

 larynx is a transverse partition, formed by two folds 

 of membrane stretching from either side but not 

 quite meeting in the middle line. They thus leave, 

 in the middle line, a chink or slit, running from the 

 front to the back, called the glottis. The two edges 

 of this slit are sharp and, so to speak, clean cut. 

 They are also strengthened by a quantity of elastic 

 tissue, the fibres of which are disposed lengthways in 

 them. These sharp free edges of the glottis are the 



