Phonological development

Phonological development refers to how children learn to organize sounds into meaning or language (phonology) during their stages of growth. Sound is at the beginning of language learning. Children have to learn to distinguish different sounds and to segment the speech stream they are exposed to into units – eventually meaningful units – in order to acquire words and sentences. One reason that speech segmentation is challenging is that unlike between printed words, no spaces occur between spoken words. Thus if an infant hears the sound sequence “thisisacup,” they have to learn to segment this stream into the distinct units “this”, “is”, “a”, and “cup.” Once "cup" is able to be extracted from the speech stream, the child has to assign a meaning to this word. Furthermore, the child has to be able to distinguish the sequence “cup” from “cub” in order to learn that these are two distinct words with different meanings. Finally, the child has to learn to produce these words. The acquisition of native language phonology begins in the womb and isn't completely adult-like until the teenage years. Perceptual abilities (such as being able to segment “thisisacup” into four individual word units) usually precede production and thus aid the development of speech production. Children do not utter their first words until they are about 1 year old, but already at birth they can tell some utterances in their native language from utterances in languages with different prosodic features. Infants as young as 1 month perceive some speech sounds as speech categories (they display categorical perception of speech). For example, the sounds /b/ and /p/ differ in the amount of breathiness that follows the opening of the lips. Using a computer generated continuum in breathiness between /b/ and /p/, Eimas et al. (1971) showed that English-learning infants paid more attention to differences near the boundary between /b/ and /p/ than to equal-sized differences within the /b/-category or within the /p/-category.