a total of 117 children , 55 girls and 62 boys with a median age of 8 years , range 2-12 years , was retrospectively evaluated in consideration of : ( 1 ) the prevalence rate and characteristics of permanent hearing loss ( defined as the average of 500 , 1000 and 2000 hz greater than or equal to 35 db hl on the better hearing ear ) ;
C0018767
hearing
C0013443
ear