552 



BELL SYSTEM TECHNICAL JOURNAL 



the sound field of the speaker when talking into the condenser trans- 

 mitter. Neither have corrections been applied for the effect of 

 leakage between the listener's ear and the earpiece of the receiver nor 



-5 



-10 

 -15 

 -20 

 -25 

 -30 



-35 



TJ -40 



I 30 



u 25 

 <n 



O 20 



Q. 



<« 15 

 bJ 



a. 



10 



5 









 -5 



-25 



FREQUENCY "* ^ 2 



Fig. 10— Response characteristics of reference transmitter, reference receiver and 

 complete reference system with db in the line. 



for the difference between the volume enclosed in the sealed chamber 

 when making the calibration as compared with the volume enclosed 

 in the ear canal when the receiver is held to the ear. The reference 



