EFFECTS OF PHASE DISTORTION 



561 



corresponding to successive elements A/, the elements being chosen so 

 as to represent equal increments of increase, say 5 per cent, on the sound 

 articulation versus cut-off frequency curve for low pass filters (Fig. 3). 



0.10 



009 



0.06 

 If) 

 O 



z 



O 0.07 



u 



UJ 



0.06 



Z 

 5 



0.05 



<Q. 3 

 vO No 



0.04 



3 0.03 

 0.02 



0.01 



400 



800 I^OO 1,600 2,000 



FREQUENCY IN CYCLES PER SECOND 



2400 



2800 



Fig. 6 — Delay distortion for an all pass network. 



The solid curve shown in Fig. 7 was calculated by multiplying the 

 arti£ulation obtained for zero phase distortion by the effective values 

 of K obtained as described above. 



Articulation tests were also made upon a system containing first one, 

 and then twenty-five 5000 cycle low pass filters in series. In both 

 cases the attenuation was equalized to 5000 cycles. Fig. 8 shows the 

 delay distortion and the articulation results that were obtained. The 

 calculated results were obtained in the manner described above. 



The foregoing calculations have not been made for the purpose of 

 setting up methods of determining the loss in articulation due to pha.se 



