66 



THE STUDY OF SPEECH CURVES. 



15.9, 15.8, 15.7, 15.8mm. This gives the series of periods 0.01183, 0.01120, 

 0.01169, 0.01134, 0.01127, 0.01134, 0.01113, 0.01106, 0.01099, 0.01106s., 

 and the frequencies 84.5, 89.3, 85.7, 88.2, 88.7, 88.3, 89.9, 90.4, 91.0, 

 90.4 in vibrations per second. Plotting the frequencies we have the " mel- 

 ody plot" in figure 54. This shows that the vowel begins low and steadily 

 rises. (For figures 54 to 64 the equation for the X-axis was lmm.= 

 0.0007s. ; the drawings were then reduced to |.) 



Let us now measure the amplitude, or maximum of vibration, for each 

 group. For this we take half the distance between the extreme point below 

 and the extreme point above. The results are 0.1,0.4,0.6, 1.1, 1.1, 1.1, 

 1.1, 1.1, 1.1, 1.1mm. Reduced to the size of the curves on the gramo- 



20O 



t50 



100 



50 



[°] [nj [a] [t] [a] [I] 



[^W'l 



Fig. .5.3. — "Oh, not really?" questioningly. 



phone plate (^-150), these give 0.0007, 0.0027, 0.0040, 0.0073, etc., from 

 which the ampUtude plot in figure 55 is obtained. The plot shows that 

 the [a] portion begins softly, but rises very rapidly to a considerable 

 amphtude, at which it remains constant for a while. 



Are these results indicative of general laws? Let us first compare them 

 with other initial vowels in the Depew record. For the beginning of [o] in 

 "on "of the phrase "on the one side in New York," the melody and ampli- 

 tude plots are shown in figures 56 and 57. The same general characteristics 

 are found in other cases in the Depew record. Compare with them the 

 melody and amplitude plots (figures 58-63) for the first ten vibrations of 

 three initial vowels, [a] in "a leaf," [o] in "also," and [x] in "America" 

 (the word was so pronounced) of the Mitchell vowel record. Like the 



