658 



BELL SYSTEM TECHNICAL JOURNAL 



-22 -20 



-16 -14 -12 -10 -8 -6 -4 -2 

 "L- VOLUME INDICATOR READING-DB 



Fig. 11 — -Distribution of speaker's levels — -87 men and 59 women. 



0.6 





0.4 



0.2 



.01 



.02 .03 .04 



Fig. 12 — -Impulse meter. 



.05 



.06 T 



T = Duration of a.c. impulse 

 a = Corresponding ultimate plate current 

 ao = Ultimate plate current for steadily applied a.c. 



