the difficulties encountered in this study were due to several factors , namely the problem involving very accurate assessment in very young children , the high incidence of tubotympanal disease in the very young , the hard to obtain definition and quantitative evaluation of the notion of progressiveness , as well as the need to analyze the evolutionary patterns in global terms ( mean hearing loss ) , from one frequency to the next and from one ear to the other , since such tone loss patterns are not always symmetric .
C0011053
hearing loss
C0013443
ear