162 PHYSIOLOGY CHAP. 



these photographs the partials present in any vowel tone within 

 the range of the resonators could be detected. 



Edison's invention of the phonograph (1877), and its perfection 

 by himself, by Graham Bell and others, reopened the whole 

 question of vowel tones, to which Fleeming-Jenkin, Ewing, 

 Hermann, Hensen, Pipping, Boeke, Lloyd, M'Kendrick, and others, 

 have contributed in the controversy. The chief question has been 

 whether each word has an absolute or a relative pitch, and whether 

 on changing the prime tone to which a vowel is sung, its principal 

 over-tones change too, as is the case with ordinary musical instru- 

 ments ; or whether the height of the partial tones which give the 

 vowel its character always remains the same, independent of the 

 pitch of the prime tone to which it is sung. 



The method employed for solving this difficult problem con- 

 sisted in taking graphic tracings of the vowel sounds, or vowel 

 phonograms, and then analysing the complex curves of these 

 sounds into the simple curves of the component tones by means of 

 Fourier's theorem. 



Bonders (1870) first applied the phonautograph of Leon Scott 

 to the investigation of vocal phonograms. In 1878 Fleeming- 

 Jenkin and Ewing employed Edison's tin-foil phonograph for 

 this purpose, although it was too imperfect to produce the sounds 

 of all the vowels clearly. These authors came to the conclusion 

 that both relative and absolute factors entered into the composition 

 of the vowels an intermediate theory already accepted by 

 Auerbach and by Helmholtz in later editions of his book. 



Hermann took up the subject about 1890, by the improved 

 wax-cylinder phonograph, and photographed the curves by a 

 beam of light, reflected from a small mirror attached to the 

 vibrating disc of the phonograph. The curves thus obtained, 

 representing the wave forms of the vowel tones, were then 

 analysed by Fourier's method. 



Hermann found that the phonograph only reproduces the 

 sung vowels accurately when the cylinder rotates at the same 

 rate as that at which they were recorded, and that the quality 

 of a vowel varies considerably with the rate of the cylinder. 

 He maintains the fixed-pitch theory, and states that there is 

 for each vowel a characteristic tone which he terms the formant. 

 He further assumes (and in this his theory differs from all others) 

 that the formant need not necessarily be a partial tone of the 

 fundamental. The pitch of the formant may vary considerably ; 

 with the same prime it may vary in certain cases as much as 

 several semitones. Fig. 104 shows in musical notation the pitch 

 of the vowel according to Hermann. 



Pipping's results in the main agree with those of Hermann. 

 He collected and analysed the vowel curves by means of Hensen's 

 gramograph. 



