METHODS 35 



home to us this question of artificial and natural methods. 



First Example : The Analysis of Audition by Helmholtz 

 and by Pierre Bonnier. 



The first example and the most suggestive of all occurs in 

 the analysis of sounds. According as we study sounds in 

 themselves, as vibratory movements, or in reference to the 

 human ear which perceives them, we find ourselves in the 

 first or in the second case already indicated, that is, with 

 absolute freedom for artificial analysis or forced to a natural 

 method of investigation. 



For the analysis of very complicated sounds, such as the 

 human voice, two methods have chiefly been in use : 



1. The graphic method, which consists in registering on 

 a turning cylinder a sinuous line traced by a stylus attached 

 to a plate made to vibrate by the voice. This method has 

 accredited itself, since the invention of the phonograph 

 allows us to reproduce the human voice thus registered 

 on a cylinder. 



2. The method of resonators, which consists in decom- 

 posing a complex sound into simple sounds, just as by the 

 prism white light is decomposed into simple lights. Helm- 

 holtz successfully applied this method to the study of the 

 human voice. He arranged in a room a great number of 

 resonators, each giving a determinate simple sound ; these 

 resonators were covered with a light layer of dust and a 

 singer placed near them uttered the sound of the vowel A, 

 for example. The figures traced in the dust on the reson- 

 ators made known which of them had vibrated ; the corres- 

 ponding simple sounds were noted and thus it was dis- 

 covered which simple sounds by their superposition pro- 

 duce the vowel A. Moreover, it was easy to verify the 

 validity of such an analysis by making all the resonators 

 noted vibrate together for this reproduced the vowel A. 



