The effects of indexical and phonetic variation on vowel perception in typically developing 9- to 12-year-old children.

PURPOSE The purpose of this study was to investigate how linguistic knowledge interacts with indexical knowledge in older children's perception under demanding listening conditions created by extensive talker variability. METHOD Twenty-five 9- to 12-year-old children, 12 from North Carolina (NC) and 13 from Wisconsin (WI), identified 12 vowels in isolated /hVd/ words produced by 120 talkers representing the 2 dialects (NC and WI), both genders, and 3 age groups (generations) of residents from the same geographic locations as the listeners. RESULTS Identification rates were higher for responses to talkers from the same dialect as the listeners and for female speech. Listeners were sensitive to systematic positional variations in vowels and their dynamic structure (formant movement) associated with generational differences in vowel pronunciation resulting from sound change in a speech community. Overall identification rate was 71.7%, which is 8.5% lower than for the adults responding to the same stimuli in Jacewicz and Fox (2012). CONCLUSION Typically developing older children were successful in dealing with both phonetic and indexical variation related to talker dialect, gender, and generation. They were less consistent than the adults, most likely because of less efficient encoding of acoustic-phonetic information in the speech of multiple talkers and relative inexperience with indexical variation.