Lexical and phonological variability in preschool children with speech sound disorder

Subtract Before You Add: Toward the Development of a De-Implementation Approach in School-Based Speech Sound Therapy

PURPOSE

It is often difficult for school-based speech-language pathologists (SLPs) to prioritize implementing new practices for children with speech sound disorders (SSDs), given burgeoning caseloads and the myriad of other workload tasks. We propose that de-implementation science is equally as important as implementation science. De-implementation science is the recognition and identification of areas that are of "low-value and wasteful." Critically, the idea of de-implementation suggests that we first remove something from a clinician's workload before requesting that they learn and implement something new.

METHOD

Situated within the Sustainability in Healthcare by Allocating Resources Effectively (SHARE) framework, we review de-implementation science and current speech sound therapy literature to understand the mechanisms behind continuous use of practices that are no longer supported by science or legislation. We use vignettes to highlight real-life examples that clinicians may be facing in school-based settings and to provide hypothetical solutions, resources, and/or next steps to these common challenges.

RESULTS

By focusing on Phase 1 of the SHARE framework, we identified four primary practices that can be de-implemented to make space for new evidence-based techniques and approaches. These four practices were determined based on an in-depth review of SLP-based survey research: (a) overreliance on speech sound norms for eligibility determinations, (b) the omission of phonological processing skills within evaluations, (c) homogeneity of service delivery factors, and (d) the use of only one treatment approach for all children with SSDs.

CONCLUSIONS

De-implementation will take work and may lead to some difficult discussions. Implementing a framework, such as SHARE, can guide SLPs toward a reduction in workloads and improved outcomes for children with SSDs.

Changes in variability during intervention for childhood apraxia of speech: implications for therapy

Typically developing children are variable in their speech production with decreasing variability indicating mastery of speech. Excessive variability which does not change over time may be an indication of unstable motor plans as often seen in children with childhood apraxia of speech (CAS). Dynamic Systems Theory (DST) provides a framework for understanding the role of variability in speech development and disorder. There are few studies that explore the impact of therapy on speech variability. This work explores the impact of therapy on perceptual speech production variability. It is a post-hoc analysis of data collected in two intervention studies of a motor-based treatment approach with children with CAS and explores DST variability effects in speech skill acquisition based on the case data from those studies. There were six participants in total across the two studies. Findings were mixed showing some non-linear changes in variability with larger changes in variability observed in participants who engaged in more extensive therapy. However, the pattern of variability change was not consistent across the participants. These findings suggest that targeting variability in therapy may be an effective way to improve the speech of children with CAS. A model for utilising variability in therapy is presented.

Speech Error Variability and Phonological Awareness in Preschoolers

PURPOSE

The purpose of this article was to investigate the relationship between speech error variability and phonological awareness.

METHOD

This article begins with a narrative review of the theoretical interpretation of speech error variability. The post hoc exploratory analysis of the relationship between speech error variability and phonological awareness included 40 children: 20 with typical speech and language and 20 with speech sound disorder and typical language. Groups were matched on gender, age, maternal education, receptive and expressive vocabulary, nonverbal intelligence, and expressive morphosyntax. Multiple regression was used to identify the best fit model for the relationship between vocabulary, speech errors, and phonological awareness.

RESULTS

Segmental variability was associated with poor phonological awareness in preschool-aged children.

CONCLUSION

Children with high levels of segmental variability have poor phonological awareness, likely due to unstable phonological representations.

Predictors of Speech Severity and Inconsistency Over Time in Children With Token-to-Token Inconsistency

PURPOSE

The aim of this study was to describe and explain changes in severity of speech sound disorder (SSD) and token-to-token inconsistency in children with high levels of inconsistency.

METHOD

Thirty-nine children (aged 4;6-7;11 [years;months]) with SSDs and high levels of token-to-token inconsistency were assessed every 6 months for 2 years (i.e., five assessment points). Growth modeling was used to assess relations among therapy support, receptive vocabulary, severity, and inconsistency over time.

RESULTS

Children with the most severe SSDs and highest levels of token-to-token inconsistency showed the smallest improvements in speech accuracy over time. Therapy support did not predict changes in speech accuracy or token-to-token inconsistency over time. Receptive vocabulary (measured at the outset of the study) was also a significant predictor of speech accuracy and inconsistency.

CONCLUSIONS

These findings suggest that an immediate start to intervention (rather than a wait-and-see approach) is recommended for children with inconsistent speech error patterns. The results also highlight the value of developing vocabulary knowledge in addition to improving speech accuracy for some children with inconsistent speech production.

Vowel errors produced by preschool-age children on a single-word test of articulation

Eighty-four children, age 4-5 years, with and without speech sound disorder (SSD) completed a battery of standardized speech and language tests, including the Goldman-Fristoe Test of Articulation, Third Edition (GFTA-3). Children with SSD produced more vowel errors than children with typical speech abilities. Percentage vowels correct and consonant error variability were highly correlated, suggesting that poorly specified phonological representations affect both consonants and vowels within a child's phonological system. However, the GFTA-3 did not contain sufficient target words to determine full vowel inventory. Using words from the GFTA-3, we present a case study of a child with vowel errors along with a sample analysis of these errors, primarily in terms of consonant-vowel feature interactions. Children who exhibit vowel errors on standardized single-word tests of speech accuracy may benefit from further vowel probes to determine how vowel and consonant errors interact in their phonological systems for more targeted therapy.

Speech inconsistency and its association with speech production, phonological awareness and nonword repetition skills

The purpose of this study was to investigate relationships between speech inconsistency, speech production skills, phonological awareness and nonword repetition (NWR) in 24 preschool-aged Finnish-speaking children with speech sound disorder (SSD) and in 31 children with typical speech and language development (TD). Speech inconsistency was assessed by a picture-naming task repeated three times during one assessment session. The participants' speech production skills were assessed with the Finnish Test for Phonology and a diadochokinetic (DDK) task. Phonological awareness was investigated by the tasks of Rhyme and initial syllable awareness and Syllable segmentation, and NWR by ten 2-4-syllabic nonwords. The findings indicated that the children with SSD were less accurate in speech production and NWR than the children with TD. No difference was found in phonological awareness. Among the children with SSD, speech inconsistency was correlated with accuracy in overall speech production, DDK task, and NWR. Among the children with TD, speech inconsistency was correlated with accuracy in overall speech production, partly with phonological awareness, and with NWR. The results provide support for the idea that when assessing speech inconsistency in children with SSD, a process-oriented approach may be needed in order to obtain an adequately broad picture of their skill profiles.

Intraword Variability in French-Speaking Monolingual and Bilingual Children

Purpose This study examines intraword variability in 40 typically developing French-speaking monolingual and bilingual children, aged 2;6-4;8 (years;months). Specifically, it measures rate of intraword variability and investigates which factors best account for it. They include child-specific ones such as age, expressive vocabulary, gender, bilingual status, and speech sound production ability, and word-specific factors, such as phonological complexity (including number of syllables), phonological neighborhood density (PND), and word frequency. Method A variability test was developed, consisting of 25 words, which differed in terms of phonological complexity, PND, and word frequency. Children produced three exemplars of each word during a single session, and productions of words were coded as variable or not variable. In addition, children were administered an expressive vocabulary test and two tests tapping speech motor ability (oral motor assessment and diadochokinetic test). Speech sound ability was also assessed by measuring percent consonants correct on all words produced by the children during the session. Data were entered into a binomial logistic regression. Results Average intraword variability was 29% across all children. Several factors were found to predict intraword variability including age, gender, bilingual status, speech sound production ability, phonological complexity, and PND. Conclusions Intraword variability was found to be lower in French than what has been reported in English, consistent with phonological differences between French and English. Our findings support those of other investigators in indicating that the factors influencing intraword variability are multiple and reflect sources at various levels in the speech processing system.

Intra-word accuracy and consistency in Finnish-speaking children with speech sound disorder compared to their typically developing peers

This study examined intra-word accuracy and consistency in 32 preschool-aged Finnish-speaking children with speech sound disorder (SSD) compared to their typically developing (TD) age- and gender-matched peers. Accuracy and consistency of speech production were assessed by a picture-naming task repeated three times in one assessment session. Responses were classified into four categories: 1) consistently correct, 2) consistently incorrect, 3) variable with hits (when a child's variable responses included at least one matched with the adult target), and 4) variable with no hits (when responses included at least two different response types without the matched adult target). In addition, relationships between intra-word accuracy and consistency and children's receptive vocabulary knowledge and articulatory ability based on spontaneous speech samples were investigated. The findings showed that the children with SSD produced significantly more often 'consistently incorrect' and 'variable with no hits' responses than the TD children. There was a significant negative correlation between 'variable with no hits' responses and receptive vocabulary knowledge and articulatory abilities among the children with SSD. As intra-word accuracy and consistency has not previously been studied in Finnish children with SSD, the findings highlighted the need for drafting guidelines for assessment and intervention by paying close attention to high intra-word variability without correct word forms already from age three onwards.

Assessment of Childhood Apraxia of Speech: A Review/Tutorial of Objective Measurement Techniques

Background With respect to the clinical criteria for diagnosing childhood apraxia of speech (commonly defined as a disorder of speech motor planning and/or programming), research has made important progress in recent years. Three segmental and suprasegmental speech characteristics-error inconsistency, lengthened and disrupted coarticulation, and inappropriate prosody-have gained wide acceptance in the literature for purposes of participant selection. However, little research has sought to empirically test the diagnostic validity of these features. One major obstacle to such empirical study is the fact that none of these features is stated in operationalized terms. Purpose This tutorial provides a structured overview of perceptual, acoustic, and articulatory measurement procedures that have been used or could be used to operationalize and assess these 3 core characteristics. Methodological details are reviewed for each procedure, along with a short overview of research results reported in the literature. Conclusion The 3 types of measurement procedures should be seen as complementary. Some characteristics are better suited to be described at the perceptual level (especially phonemic errors and prosody), others at the acoustic level (especially phonetic distortions, coarticulation, and prosody), and still others at the kinematic level (especially coarticulation, stability, and gestural coordination). The type of data collected determines, to a large extent, the interpretation that can be given regarding the underlying deficit. Comprehensive studies are needed that include more than 1 diagnostic feature and more than 1 type of measurement procedure.

Speech Production Accuracy and Variability in Monolingual and Bilingual Children With Cochlear Implants: A Comparison to Their Peers With Normal Hearing

Purpose This study investigates consonant and vowel accuracy and whole-word variability (also called token-to-token variability or token-to-token inconsistency) in bilingual Spanish-English and monolingual English-speaking children with cochlear implants (CIs) compared to their bilingual and monolingual peers with normal hearing (NH). Method Participants were 40 children between 4;6 and 7;11 (years;months; M _age = 6;2), n = 10 each in 4 participant groups: bilingual Spanish-English with CIs, monolingual English with CIs, bilingual Spanish-English with NH, and monolingual English with NH. Spanish and English word lists consisting of 20 words of varying length were generated, and 3 productions of each word were analyzed for percent consonants correct, percent vowels correct, and the presence of any consonant and/or vowel variability. Results Children with CIs demonstrated lower accuracy and more whole-word variability than their peers with NH. There were no differences in rates of accuracy or whole-word variability between bilingual and monolingual children matched on hearing status, and bilingual children had lower accuracy and greater whole-word variability in English than in Spanish. Conclusions High rates of whole-word variability are prevalent in the speech of children with CIs even after many years of CI experience, and bilingual language exposure does not appear to negatively impact phonological development in children with CIs. Contributions to our understanding of underlying sources of speech production variability and clinical implications are discussed.

Profiling Speech Sound Disorders for Clinical Validation of the Computer Articulation Instrument

Purpose The current article presents data from 2 studies on clinical groups of children referred for speech assessment. The aims of these studies are to validate the Computer Articulation Instrument (CAI) with the known-group validation method and to determine the differential diagnostic power of the resulting speech profiles. Method Study 1 examined known-group validity by comparing the scores of 93 children diagnosed with speech-language difficulties on the picture naming (PN) task of the CAI with intelligibility judgments given by speech-language pathologists. In Study 2, the speech profiles of 41 children diagnosed with speech sound disorders (SSDs), consisting of 4-6 factor scores extracted from the 4 tasks of the CAI, namely, PN, nonword imitation (NWI), word and nonword repetition, and maximum repetition rate (MRR), were validated against clinical judgments of severity of the SSD given by speech-language pathologists. Results In Study 1, a repeated-measures analysis of variance revealed a significant effect of intelligibility level on the PN performance of the CAI and there were highly significant correlations between intelligibility and PN performance in the expected direction. Neither intelligibility level nor PN performance was related to nonverbal intelligence and language scores. The analysis of variance and a series of t tests in Study 2 revealed significant differences between the moderate and severe groups for the CAI factors based on PN and NWI and the bisyllabic and trisyllabic sequences of MRR, but not for the factor word and nonword proportion of whole-word variability based on word and nonword repetition, and the monosyllabic sequences of MRR. These results suggest that, especially, the tasks PN, NWI, and the bisyllabic and trisyllabic sequences of MRR are most sensitive for diagnosing SSDs. Conclusions The findings of these 2 studies support the known-group validity of the CAI. Together with the results of a previous study of our group on reliability and validity ( van Haaften et al., 2019 ), we can conclude that the CAI is a reliable and valid tool for assessment of children with SSDs.

Intra-word consistency and accuracy in Finnish children aged 3-6 years

This study examined intra-word consistency and accuracy in typically developing Finnish children and their relation to children's vocabulary size and phonological skills. A total of 80 typically developing Finnish children aged 3;0 to 6;11 were asked to name 20 words three separate times during a single assessment session. Responses were classified into four categories: 1) consistently correct productions, 2) consistently incorrect productions, 3) variable productions with hits (variable productions including at least one matched adult target), and 4) variable productions with no hits. The results revealed that 5- and 6-year-old children produced significantly more often consistently correct responses than younger children. However, even for the 3- and 4-year old children the most frequent response type was consistently correct production. Between these two youngest age groups (3 and 4), the only significant difference was in consistently incorrect responses, which the 3-year-olds produced more often than the older children. There was a significant negative correlation between consistently incorrectly produced words and children's phonological skills, but no other relationships were found. The results indicate that when assessing children with speech sound disorder (SSD), Finnish clinicians need to take into account the fact that even 3-year-old typically developing children generally produce words correctly, either consistently or inconsistently.

Speech Inconsistency in Children With Childhood Apraxia of Speech, Language Impairment, and Speech Delay: Depends on the Stimuli

PURPOSE

The current research sought to determine (a) if speech inconsistency is a core feature of childhood apraxia of speech (CAS) or if it is driven by comorbid language impairment that affects a large subset of children with CAS and (b) if speech inconsistency is a sensitive and specific diagnostic marker that can differentiate between CAS and speech delay.

METHOD

Participants included 48 children ranging between 4;7 to 17;8 (years;months) with CAS (n = 10), CAS + language impairment (n = 10), speech delay (n = 10), language impairment (n = 9), or typical development (n = 9). Speech inconsistency was assessed at phonemic and token-to-token levels using a variety of stimuli.

RESULTS

Children with CAS and CAS + language impairment performed equivalently on all inconsistency assessments. Children with language impairment evidenced high levels of speech inconsistency on the phrase "buy Bobby a puppy." Token-to-token inconsistency of monosyllabic words and the phrase "buy Bobby a puppy" was sensitive and specific in differentiating children with CAS and speech delay, whereas inconsistency calculated on other stimuli (e.g., multisyllabic words) was less efficacious in differentiating between these disorders.

CONCLUSIONS

Speech inconsistency is a core feature of CAS and is efficacious in differentiating between children with CAS and speech delay; however, sensitivity and specificity are stimuli dependent.

Gradient perception of children's productions of /s/ and /θ/: A comparative study of rating methods

Past studies have shown incontrovertible evidence for the existence of covert contrasts in children's speech, i.e. differences between target productions that are nonetheless transcribed with the same phonetic symbol. Moreover, there is evidence that these are relevant to forming prognoses and tracking progress in children with speech sound disorder. A challenge remains to determine the most efficient and reliable methods for assessing covert contrasts. This study investigates how readily listeners can identify covert contrasts in children's speech when using a continuous rating scale in the form of a visual analogue scale (VAS) to denote children's productions. Individual listeners' VAS responses were found to correlate statistically significantly with a variety of continuous measures of children's production accuracy, including judgements of binary accuracy pooled over a large set of listeners. These findings reinforce the growing body of evidence that VAS judgements are potentially useful clinical measures of covert contrast.

Predictors of token-to-token inconsistency in preschool children with typical speech-language development

The purpose of this study was to examine potential concurrent predictors and replicate rates of token-to-token inconsistency (inconsistency in repeated productions of the same word) in 43 children with typical speech-language development, ages 2;6 to 4;2. A standard linear regression was used to determine which variables, if any, among age, expressive and receptive vocabulary, and speech sound production abilities predicted token-to-token inconsistency. Inconsistency rates in children from one research site, reported elsewhere, were compared to rates in children from a second research site. The results revealed that expressive vocabulary was the only significant predictor of token-to-token inconsistency in these children. Furthermore, inconsistency rates were similarly high across the two research sites. The findings are discussed in terms of their implications for our theoretical understanding of token-to-token inconsistency and its role in the differential diagnosis of speech sound disorders in children.

Speech Abilities in Preschool Children With Speech Sound Disorder With and Without Co-Occurring Language Impairment

Purpose

The authors compared preschool children with co-occurring speech sound disorder (SSD) and language impairment (LI) to children with SSD only in their numbers and types of speech sound errors.

Method

In this post hoc quasi-experimental study, independent samples t tests were used to compare the groups in the standard score from different tests of articulation/phonology, percent consonants correct, and the number of omission, substitution, distortion, typical, and atypical error patterns used in the production of different wordlists that had similar levels of phonetic and structural complexity.

Results

In comparison with children with SSD only, children with SSD and LI used similar numbers but different types of errors, including more omission patterns ( p < .001, d = 1.55) and fewer distortion patterns ( p = .022, d = 1.03). There were no significant differences in substitution, typical, and atypical error pattern use.

Conclusions

Frequent omission error pattern use may reflect a more compromised linguistic system characterized by absent phonological representations for target sounds (see Shriberg et al., 2005). Research is required to examine the diagnostic potential of early frequent omission error pattern use in predicting later diagnoses of co-occurring SSD and LI and/or reading problems.