SCIENTIFIC RESEARCH APPLIED TO THE TELEPHONE 257 



complicated. It is dependent upon the action of the ear, including 

 the nerve mechanism carrying the message to the brain. This 

 relationship has been under study for a number of years so that we 

 are now able to calculate from physical measurements the loudness 

 for a typical ear and also to devise instruments for measuring approxi- 



SILENT-*j !«- *\ [♦SILENT 



♦I f*SlLENT 



-3.0 

 -3.5 



-4.0 



O.a 0.3 0.4 0.5 0.6 0.7 0.8 0.9 

 TIME IN SECONDS 



I.I 1.2 1.3 1.4 



Fig. 2 — Melodic curves showing the variation of pitch with time as the sentence 

 "Joe took Father's shoe bench out" is intoned on the musical intervals do, re, mi, 

 fa, mi, re, do. The pitch changes in regular intervals rather than in irregular 

 intervals as shown in Fig. 1. 



mately the loudness of any sound. The result of using such a device 

 for recording the variations of loudness in the spoken sentence which 

 we have been discussing is shown in Fig. 3. For comparison, the 

 variations in pitch are also shown in this figure. 



If the fifteen-hundred-foot wave carrying the sentence above 

 mentioned could all be collected into an energy collector, the question 



