AN OPTICAL HARMONIC ANALYZER 



413 



WAVE FORM; 



llllllllll 



I I I I 



9 3- 



2 - 







20 



25 



30 



Fig. 4 — Analysis of saw-toothed wave. 



monies whose amplitude falls off as 1/n where n is the order of the 

 harmonic. The values obtained with this analyzer are shown in the 

 upper graph in the figure. In the lower graph each harmonic has been 

 multiplied by n, which should make all the ordinates equal if the 

 analysis were exactly correct. 



The use of the analyzer for the sounds of speech is illustrated in 

 Fig. 5, which shows the analyses of portions of two vowel sounds made 



