April 28, 1916] 



SCIENCE 



593 



employed for the objective measurement of 

 pitch and as a guide in training to sing and 

 play in pitch. The singer standing before an 

 instrimient sees in clear pictures every pitch 

 movement of the voice as he is singing ; he sees 

 exactly how many vibrations per second the 

 vocal organs are producing, and thereby can 

 tell, at the very moment of singing a note, 

 what error is involved, even down to the hun- 

 dredth of a tone; he can practise before the 

 instrument by the hour with the opportunity 

 of seeing the error in every tone and controll- 

 ing the voice and the ear by the eye at pleas- 

 ure; he can study in detail the attack, the sus- 

 taining, and the release of a single note; the 

 player of the violin, flute, cornet, or other in- 

 strument may treat his instrument in the same 

 way ; a person at a distance may connect " long 

 distance " with the tonoscope and project his 

 voice or instrument on this screen hundreds 

 of miles away; a scientist or a musician may 

 take a phonograph record of the tonal effects 

 under observation and ship the cylinder to the 

 laboratory, in which it may be reproduced 

 upon the tonoscope; the student of primitive 

 music can transcribe the phonograph record by 

 this method; the scientist can undertake tech- 

 nical studies on pitch which involve exact 

 measurements and instantaneous recording in 

 actual singing; the student of public speak- 

 ing can study the inflections of the voice ob- 

 jectively and train for mastery; the teacher of 

 the deaf can place his pupil before the instru- 

 ment and train him to speak with pleasing in- 

 flection of the voice by practising with the 

 aid of the eye. 



This array of claims may seem extravagant, 

 but these and many other related achievements 

 are made possible by the development of a 

 ready and accurate method of registering pitch. 

 The instrument which will do this is known as 

 the tonoscope, and is now available for use in 

 the studio, having been placed on the market 

 in December, 1915. 



THE TONOSCOPE 



The tonoscope^ shown in the accompanying 

 2 A full aecount of this instrument by the pres- 

 ent writer, and an article by Dr. Walter E. Miles 

 reporting investigations made by means of it, are 



illustration^ works on the principle of moving 

 pictures, technically known as stroboscopic 

 vision. It converts the sound vibrations into 

 pictures on the screen. The screen, which may 

 be seen through the opening on the front, has 

 eighteen thousand and ninety-five dots so placed 



Fig. 1. The Tonoscope. 



that, when acted upon by a sensitive light, they 

 arrange themselves in characteristic figure for 

 every possible pitch within the range of the 

 human voice. Each figure points to a number 

 on the screen which indicates the pitch. The 

 dots are arranged into one hundred and ten 

 rows; the first one has one hundred and ten 

 dots, the next one, one hundred and eleven 

 dots, and so on, each successive row having one 

 more dot than the preceding one, up to the last, 

 which has two hundred and nineteen. When 

 the tone is sounded, the row which has the dot 

 frequency that corresponds to the vibration 

 frequency of the tone will stand still, while all 



to be found in the Psychological Monograph No. 

 69, pp. 1-66, Psychological Iteview, Princeton, 

 N. J. 



3 In this illustration the sensitive flame is ener- 

 gized through a microphone; but ordinarily, simple 

 air transmission to the manometric flame through a 

 speaking tube is used. 



