A VOICE AND EAR 



299 



sound pressures of 16 bars at the plane of the guard ring at all fre- 

 quencies between 100 and 7500 c.p.s. without appreciable harmonics. 

 Speech may be transmitted about 15 db above the average intensity em- 

 ployed in commercial telephone cc^nversations without noticeable distor- 



500 1000 



FREQUENCY IN CYCLES PER SECOND 



10,000 



Fig. 3 — Response-frequency characteristic of electro-acoustic transducer 

 without equalizer. 



If) 



_) 



UJ p 



m 5 

 ^ o 

 go 



2g 



UJ LU 



500 1000 



FREQUENCY IN CYCLES PER SECOND 



I0;000 



Fig. 4 — -Response-frequency characteristic of artificial mouth. 



tion. Very few conversations are carried on at an intensity greater than 

 this. 



Measurements have been made of the magnitude of the harmonics 

 present in the output of the artificial voice under conditions of high 



