As opposed to the discontinuity hypothesis by Jakobson (1941/1968) and others, the continuity hypothesis proposed by Vihman and others implies the tacit belief that the so-called ``silent period`` may not exist in the transition from babbling to speech. For those in support of the continuity hypothesis, the silent period that may occur between the two stages of an infant`s phonological development seems to be incompatible with their observation that they are characterized as a continuum that has in common the phonetic structure of word and non-word utterances, which is statistically well analyzed by Vihman et al. (1985). This paper, however, deals with the existence of a silent period within the framework of a continuum. Much of our discussion in this paper is to explore what is happening in an infant`s brain during the same period, looking for any possibility that an infant`s phonological development may be based on what is examined from a neurobiological perspective. Following Sachs` (1988) principle of epigenetic selection, it is assumed that the involvement of both Wernicke`s area and Broca`s area in the human brain can be responsible for the active process of pruning synapses for babbling, resulting in a possible state of a silent period. (Jeju National University).