Assessing stimulability in toddlers.

This article describes the development and use of a novel, script-based stimulability task for toddlers. A detailed description of the task and procedures for administration is provided. The task assesses stimulability for fricatives, affricates, and liquids in isolation and single words through presentation of toys and objects in a script format during play. Three different levels of cueing are provided to elicit the desired sounds/words. Selected findings from examination of the performance of 10 toddlers with normal speech-language development and 10 with delayed development at an initial assessment and a 6-month reassessment are also described. Results suggest that stimulability testing may be successful with toddlers through the use of a scripted task and that they are more responsive to direct elicitations. Both groups added stimulable sounds; however, there was considerable individual variation with respect to specific sounds added and the addition of nonstimulable sounds as well. Stimulability testing is clinically useful as a dynamic assessment tool for toddlers because it may reveal information regarding a child's speech that is not obtainable with other measures and is also beneficial for individualized intervention planning.

Durations of young children's word and nonword vocalizations.

The duration of word (W) and nonword (NW) forms was examined in the monthly vocalizations of seven children between 8 and 26 months of age. The W (i.e., glossable "adultlike") forms and NW (i.e., nonglossable but phonetically transcribable) forms occurring in each child's consonant+vowel (CV) vocalizations were measured. The results were that W durations significantly decreased as a function of increasing chronological age. On the other hand, NW durations were not correlated with increasing age. The meaningfulness corresponding to W forms is hypothesized to account for the results.

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.

Relationships between acoustically determined knowledge of stop place and voicing contrasts and phonological treatment progress.

The speech of 7 children with phonological disorders (4 who failed to produce an initial voicing contrast for stops and 3 who failed to produce the alveolar-velar stop contrast) was analyzed for imperceptible acoustic distinctions for seemingly homophonous word pairs. Subjects were audio/video recorded before and during treatment as they produced minimal pairs containing their error and correct sound. Acoustic measures were VOT and CV locus equations. The presence of acoustic distinctions was taken as evidence for productive knowledge of the sound contrasts. Treatment was applied experimentally and progress was related to pretreatment productive knowledge inferred from acoustic distinctions. A shorter treatment period was observed for subjects attributed to have productive knowledge of the contrast being trained, as compared with those who had no knowledge. One of the 4 subjects with initial voicing errors produced an acoustic distinction between voiced and voiceless stops and required the shortest treatment period to establish the voicing contrast. Two of 3 subjects with velar fronting displayed coarticulatory characteristics of velars and required fewer treatment sessions in comparison with the subject with no such characteristics. Results are discussed in reference to other linguistic and nonlinguistic variables from which to predict treatment outcomes.

Lexical acquisition and acquisition of initial voiceless stops.

The interaction between lexical acquisition and acquisition of initial voiceless stops was studied in two normally developing children, aged 1;9 and 1;10, by acoustically examining the token-by-token accuracy of initial voiceless stop targets in different lexical items. Production accuracy was also examined as it related to the frequency of usage of different words, as well as the time when they entered the children's lexicons. Fewer than half of the words in the children's lexicons had tokens representing the emergence of accurate voiceless stop production prior to the session at which the voicing contrast was achieved. These words were primarily 'old' words that had been in the children's lexicons from the beginning of data collection, as opposed to 'new' words, first produced in later recording sessions. Findings are discussed in reference to the 'lexical diffusion' model of sound change and within the framework of nonlinear underspecification theory.

Acoustic validation of phonological knowledge and its relationship to treatment.

The speech of 4 phonologically disordered children with place and voicing errors affecting initial stop consonants was described through phonological and acoustic analyses. Productions of target voiced and voiceless alveolar and velar stops were transcribed and acoustically analyzed before and after treatment that was administered on a predetermined contrast. Three of the children produced significant, although largely imperceptible, differences in VOT for a given stop when it represented different adult stops. The presence of productive phonological knowledge, as inferred from acoustic data, facilitated rapid generalization of correct production of the treated contrast. In the absence of acoustically determined productive knowledge, a longer treatment period was necessary to achieve a lower level of production accuracy on the same treated contrast. Sources of speech sound errors for the 4 children were hypothesized by comparing the children's underlying representations determined from both acoustic and descriptive phonological data.

Clinical application of two phonologically based treatment procedures.

Two phonological process-based treatment procedures were applied in an ongoing clinical program. Subjects were 4 children aged 3:1, 3:8, 4:1, and 5:1. Two subjects were assigned to a minimal pairs contrasting procedure, and 2 were assigned to a modified cycles procedure based on results of a detailed phonological analysis. All children demonstrated marked changes in their phonological systems as shown by the results of pretreatment and follow-up generalization probes. Correct production generalized to sounds affected by the treatment process that were not a focus of training. Correct production of untrained sounds lagged behind that of trained sounds for all subjects. Results support the hypothesis that articulation remediation is enhanced by treating phonological processes as well as the notion that the acquisition of phonology is a gradual process. Both treatment procedures used in this study were found to be effective and efficient, as evidenced by the elimination of up to three phonological processes within 2 1/2 months for each subject.