Scientific Lectures. 193 



It was remarked that reed-pipes bad an interest for us, and it is 

 because the human vocal apparatus is essentially built on the plan of 

 a reed-pipe; the membrane in the throat, called the "vocal cords," 

 corresponds to the vibrating tongue, and the cavity of the mouth and 

 nose has the same function as the pipe. The section of a head on the 

 screen shows the relation of these parts. 



Let us make some comparative experiments. I have here the 

 vibrating tongue or reed without its pipe, and, driving the air of the 

 bellows through it, can, by varying the acting size of the tongue, 

 draw from it a series of different notes, which have a quality which is 

 evidently due to complexity ; none of the notes sound in the least 

 like that of the tuning-fork. Corresponding to this, I have, in my 

 hand artificial human vocal cords, made of sheet india rubber, and, as 

 you hear, can, by stretching them more or less, draw from them a 

 series of inharmonious, semi-human tones, which break up from time 

 to time into an inarticulate howling. I add to my reed a short coni- 

 cal pipe ; the quality of its sound is entirely changed, although the 

 fundamental note is unaltered, and, opening and closing it with the 

 hand, I easily cause it to pronounce the words, " ma, ma." Next, I 

 supply my artificial vocal cords with a short, broad pipe or cylinder 

 (slightly conical), and they easily utter sounds like " pop-par." Remov- 

 ing the cylinder, and substituting for it this glass flask, we have it 

 pronouncing the words, "pa, pa," with , a somewhat nasal twang. 



All this shows that, by varying the shape and size of the pipe, or 

 the cavity and opening of the mouth, without in the least altering the 

 fundamental note, we can strengthen or weaken particular sets of the 

 higher notes which accompany it, and thus entirely alter the quality 

 of the resulting sound. 



"We are now ready to make an application of the information we 

 have gained. The vowel sounds are the simplest articulate sounds 

 uttered by the human voice ; and, quite recently, they have been 

 analyzed by Germany's greatest living physicist (I refer to the cele- 

 brated Ilelmholtz), who has confirmed the idea previously suggested 

 by Willis, that they consist of a fundamental note, mingled in certain 

 proportions with notes that are higher. The fundamental tones -and 

 the higher tones are simultaneously generated by the vibrating vocal 

 cords, and by altering the shape, size and opening of the cavity of the 

 mouth, particular tones or notes are strengthened or weakened, and 

 vowel sounds are produced. Thus, Ilelmholtz found that the sound 

 O was produced by the mixture of the fundamental note with its 

 higher octave or first harmonical, the second harmonical or its duo- 



flNST.] 13 



