378 



HF.LI. SYSTEM I l-.CIIMC.IL JOCKXAL 



nx 



N "Mo! 



1-ig. 2 — Maskiiii; for To 



'400 600 800 1000 leOO 1600 eOOO tW two 3200 3600^000 



FR[QUENCYOF MASKED TONE 



(•"ig. 3 — Masking of Wirioiis I'rcniiciuirs l)V 1,20() Cycles at Sensation Levels of 

 H(\, fid, .III. I 44 I niiv, Rrspertively 



