Babbling and Early Words

Pre-speech vocalizations are divided into reflexive vocalizations (e.g., cries, coughs, hiccups), which are related to the baby's physical state, and nonreflexive vocalizations (e.g., cooing, playful productions, yelling), which contain phonetic and syllabic features of speech. Both vowels and consonants appear in nonreflexive vocalizations, and the most prevalent syllable structure is a consonant followed by a vowel (CV; e.g., \ba\, \du\, \ke\). The overall composition of pre-speech vocalizations changes dramatically during the first year of life. In the first six months, babies all over the world sound alike. During this period, vowels predominate and are supported by prolonged back consonants (e.g., \k\, \g\). During the next six months, the sound repertoire significantly expands, with a marked shift toward more frontal consonants. John Locke reported in 1993 that, by their first birthday, American English-speaking infants produce stops (\p\, \b\, \t\, \d\, \k\, \g\), nasals (\m\, \n\), and glides (\w\, \j\).