Durational analysis of stridency errors in children with phonological impairment

This study investigated children's knowledge, evidenced acoustically, of contrasts involving stridents as related to treatment progress. Durational measures (VOT) were used to examine possible acoustic markers of /s/ + stop clusters vs. stop singleton contrasts and initial fricative vs. stop contrasts in six pre-school children with phonological impairment. Other aspects of the children's phonological knowledge were examined for their correspondence to acoustic findings and to treatment progress. One of three stopping subjects produced a durational acoustic distinction between stop and fricative targets prior to treatment. This subject, who also had more knowledge of the fricative class, required the shortest treatment period to establish a contrast between initial stops and fricatives in comparison to two subjects who had less knowledge of fricatives and no acoustic distinction. All three cluster subjects produced long lag VOTs in stops that replaced /s/ + stop clusters; one of these children displayed a weak signilicant difference in VOT means for is/ + stop cluster and singleton targets, but was not the subject with the lowest number of treatment sessions. Results are discussed in reference to the utility of acoustic measures and the convergence of those measures with other sources of knowledge as it relates to treatment outcomes.