when the figures were calculated to represent the whole material of 11 748 cases , marked hearing loss , pta greater than 25 db in the better ear , was found in 64 children , 0.5 % , minor loss , greater than 20 db at 4 khz but pta less than 25 db in the better ear , in 420 children , 3.6 % , and slight abnormality , greater than 20 db , at any frequency in 1 224 , 10.4 % .
C0011053
hearing loss
C0013443
ear