AUDITORY DEVELOPMENT OF THE HEARING CHILD

Auditory perception is defined, here, as the interpretation of sensory evidence, derived from sound, in terms of the objects and events that caused the sound. Like other kinds of perception, it involves the use , not only of sensory evidence, but also of contextual evidence, prior knowledge, memory, attention, and processing skills. Auditory speech perception is special because the events to be perceived are those of language. Similarly, the listener's knowledge base and processing skil ls must include those related to language in general, and spoken langu age in particular. The auditory system is complete and functional at b irth but myelination continues for several years in the higher auditor y pathways. This pattern of anatomical maturation is reflected in elec trophysiological responses. Similarly, infants display sophisticated d iscrimination and recognition ability but psychoacoustic performance d oes not reach adult levels for several years. Empirical data on the de velopment of auditory processing are sparse, but much work has been do ne on auditory speech perception. Infants at 6 months demonstrate the beginnings of phonemic classification, and performance improves during childhood in a variety of areas. These include: phonetic contrast per ception, phoneme recognition, perception of speech in noise, selective attention, and the use of linguistic context. Experience obviously pl ays a key role in the development of the knowledge and skills required for auditory perception in general and auditory speech perception in particular. It is tempting to assume that the sensory evidence availab le to the developing child is determined only by the functional integr ity of the peripheral auditory system, independent of auditory experie nce. There is, however, increasing evidence in animals of the influenc e of auditory experience on the organization of the auditory pathways. Such organization could increase the sensory evidence made available from patterns of neural excitation produced in the cochlea.