Although supporters of the Critical theory have created compelling arguments for their ideas, many professionals have criticized them and stated that there is no real critical period for learning language, instead some say the Critical period is a:
Werker & Pegg (1992) state that instead of losing language it goes through a Perceptual reorganization process. During this time language is placed in the child’s own categories and learned through their language rules. (Psychology of language, p 263)
DeVillers & DeVillers (1978) State that the critical period is more like a period of Heighten sensitivity to language and it is a time where the child developed their natural communication mode (hands of voice) and their primary training channel (visual, or aural).