Phonological Development

Phonological development entails the acquisition of knowledge about the sound system of the ambient language for the purpose of comprehending that language and producing it intelligibly. The process of phonological development is long and complex because the sound system of any language is organized in a hierarchical fashion across many interacting tiers so that the child must acquire many types of knowledge. If a child’s acquisition of even a simple word such as doggies (in English) is considered, it is clear that several tiers of phonological structure are invoked: There are two syllables produced with a strong–weak stress pattern; the syllables are composed of segments, specifically consonants (C) and vowels (V), slotted into onset (/d/, /ɡ/), nucleus (/ɑ/, /i/), and coda (/ɡ/, /z/) positions within the syllables; and each of these C and V segments are characterized by bundles of distinctive features that differentiate, for example, the obstruents (/d/, /ɡ/, /s/) from sonorants (/ɑ/, /i/), stops (/ɡ/, /d/) from the fricative (/s/), voiced (/d/, /ɡ/) from voiceless (/s/), and coronal (/d/, /s/) from dorsal (/ɡ/) consonants. Furthermore, knowledge of these tiers of the phonological hierarchy must be acquired at multiple levels of phonological representation. Knowledge of acoustic-phonetic features permits perception of speech and supports production learning by providing an acoustic target for production practice. Articulatory-phonetic knowledge includes the specific articulatory gestures associated with individual speech sounds as well as the ability to produce varying sequences of speech sounds smoothly. Phonological knowledge involves learning to manipulate phonological units at multiple tiers of the phonological hierarchy so as to contrast meaning, using rules that are specific to the ambient language. For example, in English, /d/ and /ɡ/ are separate phonemes that can occur in the same syllable positions to contrast meaning across word pairs such as /dɪɡ/ and /dɪd/ or /dɔɡ/ and /ɡɔd/. This kind of phonemic knowledge is required to ensure that [d] and [ɡ] are produced distinctly and in the correct order to produce the word doggies.

Incomplete phonological knowledge, leading to substitutions or omissions at any of the tiers of the phonological hierarchy, would change the intended meaning of an utterance. Therefore, even at a young age, a child must master a fair degree of precision in the acoustic-phonetic, articulatory-phonetic, and phonological domains to produce intelligible speech. To produce lengthy complex utterances at the rate and precision typical of an adult speaker requires so much practice that phonological development is not complete until the late teenage years. Developmentally, phonetic knowledge emerges before phonemic knowledge. Therefore, a 6-month-old infant may be capable of producing utterances that contain the [h], [m], [æ], and [t] sounds without knowing the meaning of a single word. An adult, aware that the words hat and mat have different meanings, perceives the acoustic differences between the phones [h] and [m] and comprehends the functional contrast between the phonemes /h/-/m/. Phonological knowledge as defined here is concerned with the comprehension and production of meaningful utterances and requires the integration of acoustic-phonetic, articulatory-phonetic, and phonological knowledge at multiple tiers of the phonological hierarchy. For this reason, the earliest stages of speech perception and speech production development are referred to as prelinguistic, even though much language-specific perceptual knowledge emerges and the onset of babbling occurs during the first year of life. This entry explores the stages of phonological development, from early word learning to increased segmental accuracy and, eventually, to mastery of speech accuracy. This account of phonological development begins during the second year of life when the infant begins to understand and produce meaningful words.

...