The acquisition of medial /t, d/ allophones in bisyllabic contexts.

The acquisition of medial /t, d/ allophones was examined in four children between 2 and 5 years of age, over a period of 38 months. Children labelled pictures designed to elicit a sample of these allophones in iambic ([t]) and trochaic (flap, nasal and lateral release) contexts. Productions were analysed with reference to attainment of target allophones and use of non-target segmental (e.g., [d] or [t] in place of flap) and syllabic variants (e.g., unstressed syllable deletion). All children produced the target [t] allophone in iambic context. Across children, between 10 and 15 variants occurred in trochaic contexts. Nasal and lateral release allophones were never attained. Flap attainment was variable, with significant differences across children and across phonetic contexts. Results suggest a hierarchy of /t, d/ allophone production with reference to prosodic and phonetic contexts. Discussion includes implications of these findings for clinical intervention.