  At this time, however, there are still very few case reports in the  literature, and the data so far obtained in these studies are  equivocal with respect to the sensitive and critical period  hypotheses. Some adolescents do seem to be able to acquire language  despite early linguistic deprivation, and others do not. It is  unclear what the explanation of these different outcomes is, but one  important factor appears to be whether the new language is a signed  language (e.g., ASL) or a spoken language. Perhaps because their  childhood perceptual deficits prevented normal auditory and  articulatory development, deaf children whose hearing is restored  later in life do not seem to be able to acquire much in the way of  spoken language. (Grimshaw et al. 1998.)