302 E. W. Scripture — Nature of Vowels. 



Art. XXIV.— On the Nature of Vowels ; by E. W. 

 Scripture, Yale University. 



The speech curves, which are discussed in this paper, were 

 traced off with great accuracy from several gramophone plates 

 by a specially constructed apparatus. The method is essen- 

 tially as follows : The rubber gramophone plate is slowly 

 rotated (once in 5 hours) in such a way that the curve travels 

 under a fine steel point. The point is thus deflected sidewise 

 according to the vibrations in the speech curve ; its movement 

 is magnified by a system of levers and is recorded on a surface 

 of smoked paper. An earlier form of this apparatus has 

 already been described* ; the present form will be described 

 later. 



The curves, shown in fig. 1, are from a plate containing the 

 nursery rhyme of Cock Robin, spoken by an American. The 

 equation beneath the figure indicates the relation between 

 length and time. 



The curve for / shows a series of vibrations in which each 

 group resembles the neighboring one while there is a gradual 

 change in character from a typical form for the a in the first 

 part, to a typical form for the i in the second part, of the 

 diphthong ai of which the pronoun I is composed. In the 

 first portion there appears a succession of strong vibrations 

 each followed by a series of weaker ones. These strong vibra- 

 tions recur at periods of steadily decreasing length. 



If we consider separately each group of vibrations begin- 

 ning with a strong one, we find that it is, aside from minor 

 details, the typical curve of a vibration initiated by a blow and 

 dying away by friction, for which the equation is 



y = a.e~ kt . sin 2-n- „ , 



where y is the elongation at the moment t, a the amplitude, e 

 the basis of the natural series of logarithms, h a factor repre- 

 senting friction and Tthe periodic time. 



The succeeding groups of vibrations following the first 

 group are of the same form but of steadily increasing ampli- 

 tude. They recur at steadily decreasing intervals. The 

 formula for each group is approximately the same except for 

 the difference in amplitude. The vibrations are evidently 

 aroused by a series of blows of steadily increasing strength at 

 steadily decreasing intervals. 



* Studies from the Yale Psychological Laboratory, vol. vii. 



