No abstract

Purpose The purpose of the study was to determine whether distinct subgroups of preschool children with speech sound disorders (SSD) could be identified using a subgroup discovery algorithm (SUBgroup discovery via Alternate Random Processes, or SUBARP). Of specific interest was finding evidence of a subgroup of SSD exhibiting performance consistent with atypical speech motor control. Method Ninety-seven preschool children with SSD completed speech and nonspeech tasks. Fifty-three kinematic, acoustic, and behavioral measures from these tasks were input to SUBARP. Results Two distinct subgroups were identified from the larger sample. The 1st subgroup (76%; population prevalence estimate = 67.8%–84.8%) did not have characteristics that would suggest atypical speech motor control. The 2nd subgroup (10.3%; population prevalence estimate = 4.3%– 16.5%) exhibited significantly higher variability in measures of articulatory kinematics and poor ability to imitate iambic lexical stress, suggesting atypical speech motor control. Both subgroups were consistent with classes of SSD in the Speech Disorders Classification System (SDCS; Shriberg et al., 2010a). Conclusion Characteristics of children in the larger subgroup were consistent with the proportionally large SDCS class termed speech delay; characteristics of children in the smaller subgroup were consistent with the SDCS subtype termed motor speech disorder—not otherwise specified. The authors identified candidate measures to identify children in each of these groups.

This study explores the effects of hearing status and bite blocks on vowel production. Normal-hearing controls and postlingually deaf adults read elicitation lists of /hVd/ syllables with and without bite blocks and auditory feedback. Deaf participants' auditory feedback was provided by a cochlear prosthesis and interrupted by switching off their implant microphones. Recording sessions were held before prosthesis was provided and one month and one year after. Long-term absence of auditory feedback was associated with heightened dispersion of vowel tokens, which was inflated further by inserting bite blocks. The restoration of some hearing with prosthesis reduced dispersion. Deaf speakers' vowel spaces were reduced in size compared to controls. Insertion of bite blocks reduced them further because of the speakers' incomplete compensation. A year of prosthesis use increased vowel contrast with feedback during elicitation. These findings support the inference that models of speech production must assign a role to auditory feedback in error-based correction of feedforward commands for subsequent articulatory gestures.