Introduction

In his seminal paper in the field of child phonology, Jakobson (1941/1968) referred to the prelinguistic period of vocal development (babble) as, ‘the purposeless egocentric soliloquy of the child’ and as ‘biologically oriented “tongue delirium”’ (Jakobson, 1968: 24). Both expressions reflect a general opinion, which may have been widely held at the time, that babble is unrelated to language and that the study of language development should begin at the point when children begin producing true words. Over the past several decades, however, researchers in the area of language development in general and child phonology in particular have investigated the phonetic similarities between babble and early words and have identified important relationships between prelinguistic vocalization and later language ability.

Continuity between Babble and Speech

One of the major findings in this area is the observation of continuity between prelinguistic vocalization and the later period of meaningful speech. A number of studies have shown that the phonetic characteristics of early words are similar to the phonetic characteristics of babble: simple syllable shapes with stops, nasals and glides dominate in both babble and early speech (Stoel-Gammon, 1998b). This continuity between babble and early words has also been observed at the level of the individual child in that specific sound pattern preferences in babble have been found to carry over into meaningful speech, forming the building blocks for an individual child’s early lexicon (Vihman, 1993). For example, one child studied by Ferguson and Farwell (1975) showed a marked preference for acquiring words with sibilant consonants, while another child described by Stoel-Gammon and Cooper (1984) had a disproportionate number of words with velar stops in his early expressive vocabulary. These observations suggest that the prelinguistic and early linguistic stages of vocal development are not discrete, separable stages, but are rather part of a continuous developmental trajectory in which speech production ability acquired during babbling is used by the child as he begins to produce true words that approximate the adult target.