Compensatory articulation in normal and phonologically disordered children

Abstract

Many researchers have found that adults can compensate for the effect of bite block and produce acoustically normal vowels, even on the first glottal pulse. Do normal and phonologically disordered children demonstrate similar evidence of motor equivalence during speech? Eight normal and four phonologically disordered preschool children said the words “heat,” “hit,” and “hat” in three conditions: control, with a 10‐mm custom‐fitted bite block, and with clenched teeth. The frequency of the first and second formants for /æ/ and the second formant for /i/ and /ɪ/ were measured. Acoustic effects of the fixed jaw positions were observed for all of the children. Adult listeners were also asked to identify the children's productions of the words and to rate vowel “typically” using a three‐point equal interval scale. Perceptual effects for the fixed‐jaw position vowels were observed. These results are consistent with the results of other studies, which suggests that motor equivalence for speech develops gradually. Three of the four phonologically disordered children differed from the normal children in displaying more idiosyncratic patterns of noncompensation.