PHYSICAL MEASUREMENTS OF AUDITION 



161 



Masking of One Pure Tone by Another 



We are now in a position to discuss another set of facts concerning 

 the perception of tones, namely, the ability of the ear to perceive 

 certain sounds in the presence of other sounds. Such data for pure 

 tones have been obtained in our laboratories and will soon be pub- 

 lished in some detail. The apparatus used consisted simply of two 

 vacuum tube oscillators generating the two tones used and two 

 attenuators which made it possible to introduce the tones into a single 

 receiver with any desired intensities. In other words, it consists of 

 two audiometers with a common receiver for generating the two 

 tones. The curves shown in Fig. 8 give the general character of the 

 results of this work. 



Monaural Masking 



400 Cycles 



m0 600 1200 1600 2000 2m 2800 3200 3600 WOO 

 Frequency of Vibration 



1200 Cycles 



400 800 1200 1600 2000 2m 2800 320036001000 

 Frequency of Vibration 



m 800 WO 1609 2000 1 

 Frequency of I 



16003200 3600 4000 



Fig. 8 



