LSHSS

Research Article

Speech Abilities in Preschool Children With Speech Sound Disorder With and Without Co-Occurring Language Impairment Toby Macraea and Ann A. Tylerb

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.

T

shown to exhibit poorer auditory discrimination (Nathan, Stackhouse, Goulandris, & Snowling, 2004); phonological awareness (PA; Lewis et al., 2011; Nathan et al., 2004; Sices, Taylor, Freebairn, Hansen, & Lewis, 2007); phonological memory (Lewis et al., 2011; Nathan, Stackhouse, & Goulandris, 1998; Sices et al., 2007); underlying representations for words (i.e., stored information necessary for the recognition and production of words; Stoel-Gammon, 2011) (Nathan et al., 1998); vocabulary (Lewis et al., 2011); narrative abilities (Wellman et al., 2011); and perhaps most importantly, reading, spelling, and written language skills (Bird, Bishop, & Freeman, 1995; Bishop & Adams, 1990; Catts, 1993; Lewis & Freebairn, 1992; Lewis, O’Donnell, Freebairn, & Taylor, 1998; Nathan et al., 2004; Peterson, Pennington, Shriberg, & Boada, 2009; Sices et al., 2007; Skebo et al., 2013). As a group, children with preschool histories of SSD are at increased risk of developing reading problems. It appears to be the presence of co-occurring LI, however, that accounts for much of this risk (Peterson et al., 2009).

he prevalence of speech sound disorder (SSD) has been estimated at 15%–16% in 3-year-old children (Campbell et al., 2003; Shriberg et al., 2005) and 3.8% in 6-year-old children (Shriberg, Tomblin, & McSweeny, 1999). SSD is the most common communication disorder type on pediatric speech-language pathologists’ (SLPs) caseloads (Broomfield & Dodd, 2004). A large subgroup of children with SSD is those with co-occurring SSD and language impairment (LI; see Tyler, Lewis, Haskill, & Tolbert, 2003). While 50%–75% of preschool children with SSD have cooccurring LI (Shriberg & Kwiatkowski, 1994), approximately 14% of 6-year-old children with SSD have co-occurring LI (Shriberg et al., 1999). In comparison with children with SSD only, those with co-occurring SSD and LI have been

a

Florida State University, Tallahassee, FL Western Michigan University, Kalamazoo Correspondence to Toby Macrae: [email protected]

b

Editor: Marilyn Nippold Associate Editor: Linda Larrivee Received October 16, 2013 Revision received April 30, 2014 Accepted July 26, 2014 DOI: 10.1044/2014_LSHSS-13-0081

302

Key Words: speech sound disorder, language disorders, phonology, diagnostics, error patterns, phonological processes

Disclosure: The authors have declared that no competing interests existed at the time of publication.

Language, Speech, and Hearing Services in Schools • Vol. 45 • 302–313 • October 2014 • © American Speech-Language-Hearing Association

Error Patterns One area about which relatively little is known is speech sound production in children with co-occurring SSD and LI. These children’s co-occurring language deficits may manifest as quantitatively and/or qualitatively different surface speech behavior in comparison with children with SSD only. Children with co-occurring SSD and LI may present with more severe SSDs than children with SSD only (Nathan et al., 1998, 2004; Sices et al., 2007). They may also show differences in the error patterns they use. Whereas more global measures of speech performance and severity of SSD allow for a quantitative comparison, error pattern analyses allow for a qualitative comparison (Preston & Edwards, 2010). Error patterns, or as they were referred to then, phonological processes, were described in the theory of natural phonology as reflecting “mental substitutions which systematically but subconsciously adapt our phonological intentions to our phonetic capacities” (Donegan & Stampe, 1979, p. 126). According to Stampe (1969), infants’ first words likely reflect the full range of these phonetic restrictions on speech output. As children are exposed more and more to the adult form, they gradually suppress these patterns so that their word productions match the adult form. Children who fail to suppress error patterns may be diagnosed with SSD. More recently, researchers and clinicians have begun to interpret certain error patterns, including atypical error patterns and omission error patterns, as reflecting distinct underlying deficits in children with SSD (e.g., Dodd, Holm, Crosbie, & McCormack, 2005; Shriberg et al., 2005). Atypical error patterns are simplifications that are not used by the majority of children with typical phonological development. Omission error patterns are those that involve the omission of a syllable or phonemes (e.g., weak syllable deletion, final consonant deletion, and cluster reduction). Identifying differences in error pattern use between children with co-occurring SSD and LI and children with SSD only is clinically and theoretically important. Differences in error pattern use may shed light on the nature of the deficit(s) underlying the different types of patterns. If certain patterns are used more frequently by children with co-occurring SSD and LI, then these patterns may reflect more global linguistic deficits in comparison with those used more frequently by children with SSD only. These patterns may aid in the early identification of children who are at risk of developing co-occurring SSD and LI and also, therefore, later reading problems. For example, Foy and Mann (2012) found that omission error pattern use at the beginning of kindergarten was significantly correlated with nonword reading at the end of the year in children with typical development. Although speech-language impairments often remain undiagnosed in preschool children (Tomblin et al., 1997), surface speech behavior associated with a linguistic deficit may be relatively easy to identify by parents, teachers, and SLPs at a young age. Campbell, Dollaghan, Needleman, and Janosky (1997) and Dollaghan and Campbell (1998) argued for the

use of processing-dependent measures in diagnosing LI because they reflect underlying language processing deficits. Norm-referenced language tests, which are often the sole basis for diagnosing LI, rely too much on experiential knowledge. Furthermore, identification rates of preschool children with speech-language impairments are low. In an epidemiologic study involving 7,218 kindergarten-age children, only 29% of parents of children diagnosed with specific language impairment (SLI) had been informed that their child had a speech-language impairment (Tomblin et al., 1997). According to Tomblin (1996), speech production abilities were the main determinant of a parent being told of a speech-language impairment in their child. An example of a processing-dependent measure used to diagnose LI is nonword repetition (NWR). Research has identified NWR difficulties in children with SLI (Catts, Adlof, Hogan, & Weismer, 2005; de Bree, Rispens, & Gerrits, 2007; Dollaghan & Campbell, 1998; Gathercole & Baddeley, 1990; Kamhi & Catts, 1986). Indeed, NWR has been identified as a potential psycholinguistic marker of SLI in children (Conti-Ramsden & Botting, 2001). In a similar vein, research is required to identify speech error patterns that are characteristic of children with co-occurring SSD and LI. These error patterns can then be explored further for their ability to predict co-occurring SSD and LI in young children. A benefit of using error patterns to identify children at risk of co-occurring SSD and LI is that error patterns may reveal themselves in conversational speech at a young age (i.e., younger than 3 years old). This will allow parents, teachers, and SLPs to identify these children early and employ preventative speech-language intervention. Identifying error pattern differences in children who differ in their language status is methodologically challenging. Research has revealed more severe SSDs in children with co-occurring SSD and LI than children with SSD only (Nathan et al., 1998, 2004; Sices et al., 2007). Furthermore, children with severe SSDs have been shown to use more omission error patterns than children with mild-moderate SSDs (Ruscello, St. Louis, & Mason, 1991). Children with co-occurring SSD and LI, therefore, would be expected to show differences in error pattern use in comparison with children with SSD only because of their more severe SSDs. Before qualitative differences in speech behavior can be attributed to differences in language status between comparison groups, researchers must first identify groups with similar levels of severity of SSDs.

Atypical Error Patterns One category of speech error patterns that has been interpreted as reflecting a distinct underlying deficit in children with SSD is atypical error patterns. These have been shown to predict PA skills (Mann & Foy, 2007; Preston & Edwards, 2010) and differentiate between children with good and poor PA skills (Leitao & Fletcher, 2004; Leitao, Fletcher, & Hogben, 2000; Leitao, Hogben, & Fletcher, 1997; Rvachew, Chiang, & Evans, 2007). Atypical error patterns may reflect poor phonological processing skills and weak

Macrae & Tyler: Speech Abilities in Preschool Children

303

underlying phonological representations (Dodd & Lacano, 1989; Dodd, Leahy, & Hambly, 1989; Leitao & Fletcher, 2004; Leitao et al., 1997; Preston & Edwards, 2010). Phonological processing is a broad term that refers to “various linguistic operations that make use of information about the speech sound (i.e., phonological) structure of the language” (Catts, 1989, p. 101). Specific operations thought to make up phonological processing include encoding, storage, retrieval, production, and explicit awareness of speech sounds (Catts, 1989; Catts, Kamhi, & Adlof, 2012; Leitao et al., 1997). Given the link between phonological processing and word decoding deficits, as identified in previous studies (Kamhi & Catts, 2012; Wagner & Torgesen, 1987), children who show frequent use of atypical error patterns may be at risk for reading and spelling problems (Leitao et al., 1997). Indeed, these children have shown difficulties with word decoding, nonword spelling, real word spelling (Leitao et al., 2000), and reading comprehension (Leitao & Fletcher, 2004). Atypical error patterns are also thought to be associated with poor speech normalization. Leonard (1973) suggested that children who use atypical error patterns be given priority for speech intervention as their phonological systems are not likely to normalize without it. Leahy and Dodd (1987) confirmed this in a 3-year-old child who used predominantly atypical patterns. In the absence of intervention, the child showed little change in the number and types of error patterns used. After several sessions of intervention that targeted her use of atypical patterns, she showed a decrease in her use of these patterns and an increase in consonant accuracy. Dodd and Lacano (1989) also found that intervention targeting atypical patterns can lead to decreases in their use. Seven children with SSD characterized by atypical error pattern use, ages 3;0 (years;months) to 4;9, received therapy that targeted only these patterns. Across all participants, results revealed a significant decrease in the number of atypical patterns used and a significant decrease in the frequency of their use between pre- and posttreatment.

Omission Error Patterns Another category of speech error patterns thought to reflect an underlying cognitive-linguistic processing deficit in children with SSD is omission error patterns (Shriberg et al., 2005). Shriberg and colleagues have conducted a number of studies that have examined omission error patterns in children with SSD. For example, Shriberg, Kwiatkowski, and Gruber (1994) found that the use of omission patterns differentiated between 3- to 6-year-old children with SSD whose speech did and did not normalize over time. None of these differences were tested for significance. Shriberg et al. (2005) examined potential diagnostic markers of genetically transmitted SSD. Children with an increased genetic load for SSD (i.e., those with two or more nuclear family members with current or prior speech-language impairment) showed significantly more frequent use of omission patterns than children with a decreased genetic load for SSD.

304

Furthermore, there was a nonsignificant trend for more children with an increased genetic load for SSD to have comorbid LI than children with a reduced genetic load. Shriberg et al. (2005) argued that these findings support the contention that frequent use of omission patterns is consistent with a genetically transmitted cognitive-linguistic processing deficit: “whereas substitutions . . . and distortions indicate at least partial underlying knowledge of the target phoneme, phoneme deletions may indicate lack of phonological representation of targets (i.e., to encode, store, and/or successfully retrieve them)” (p. 847).

Summary and Purpose Although there exists a large body of research examining phonological processing, literacy skills, and vocabulary knowledge in children with co-occurring SSD and LI, little is known about their speech production patterns. The purpose of this study was to compare children with cooccurring SSD and LI with those with SSD only in their numbers of speech sound errors and types of error patterns. Groups were compared in measures of speech performance and severity of SSD and measures of error pattern use, including omission, substitution, distortion, typical, and atypical error patterns. Although omission and atypical patterns have some commonalities (e.g., they are both associated with poor speech sound normalization), each may reflect a unique underlying deficit in children with SSD. Frequent use of atypical patterns is associated with poor PA, reading, and spelling skills and has, therefore, been linked to a phonological processing deficit. Omission patterns, on the other hand, are associated with co-occurring LI in children with SSD, although no study has directly compared children with co-occurring SSD and LI with those with SSD only in their use of omission patterns. Omission patterns are thought to reflect absent phonological representations for target sounds and perhaps a more global cognitive-linguistic processing deficit in contrast to atypical patterns. Given these differences, it was hypothesized that omission patterns, but not atypical patterns, would be used more frequently by children with co-occurring SSD and LI in comparison with children with SSD only.

Method Participants Participants included 28 children, ages 3;6 to 5;5 (21 males and 7 females). The SL Group (SSD + LI) contained 15 children, ages 3;10 to 5;2 (12 males and 3 females), with co-occurring SSD and LI. The S Group (SSD) contained 13 children, ages 3;6 to 5;5 (9 males and 4 females), with SSD only. The SL Group was part of an earlier study that compared the relative effects of an integrated phoneme awareness and speech intervention and an alternating speech and morphosyntax intervention on phoneme awareness, speech sound production, and expressive language in American and New Zealand children with co-occurring SSD and LI (Tyler, Gillon, Macrae, & Johnson, 2011).

Language, Speech, and Hearing Services in Schools • Vol. 45 • 302–313 • October 2014

Preintervention data were used for the present study. For these children, the presence of SSD was confirmed by a score below the typical range for their age (>1 SD below the mean) on the Goldman Fristoe Test of Articulation— Second Edition (GFTA–2; Goldman & Fristoe, 2000). These children were also administered 25 additional words from Dodd’s Inconsistency Assessment (Dodd, 2005). In the original study, LI was confirmed in 18 children who formed the U.S. cohort by a score below the typical range for their age (>1 SD below the mean) on the Structured Photographic Expressive Language Test—Preschool, Second Edition (SPELT–P2; Dawson et al., 2005) and/or > 1.5 SDs below the mean in mean length of utterance in morphemes (MLUm) for the child’s age based on Miller and Chapman’s (2000) normative data. The SPELT–P2 assesses a child’s use of morphological and syntactical structures and pronouns. For the present study, MLUm was not used as a selection criterion. Only those participants with SPELT–P2 scores below the typical range were retained to form the SL Group. One participant was excluded on this basis, and assessment data were unavailable for two, leaving 15 children in the SL Group. The S Group was part of an earlier study that examined relationships among measures of speech variability in children with SSD (Macrae, Tyler, & Lewis, 2014). For these children, the presence of SSD was confirmed by a score below the typical range for their age (>1 SD below the mean) on the Bankson–Bernthal Test of Phonology (Bankson & Bernthal, 1990). These children were also administered 20 additional words. Although language was not a selection criterion in the Macrae et al. (2014) study, all participants were administered the Core Language subtests (i.e., Sentence Structure, Word Structure, and Expressive Vocabulary) of the Clinical Evaluation of Language Fundamentals—Preschool, Second Edition (CELF–P2; Semel, Wiig, & Secord, 2004). These subtests assess a child’s ability to understand spoken sentences; use morphological and syntactical structures and pronouns; and label people, objects, and actions; respectively. For the present study, only those participants whose Core Language Scores and Word Structure subtest scaled scores from the CELF–P2 were within the typical range for their age (≤1 SD below the mean) were retained to form the S Group. The Word Structure subtest, like the SPELT–P2, assesses the use of morphological and syntactical structures and pronouns. Five of the original 18 participants were excluded on this basis, leaving 13 children in the S Group. In the present study, percent consonants correct (PCC, a measure of severity of SSD; Shriberg & Kwiatkowski, 1982) was calculated from the stimulus words from the standardized tests of articulation and phonology and the additional words. MLUm was calculated for both groups from narrative story retells using the Systematic Analysis of Language Transcripts computer program (Miller & Chapman, 2000). Children in the SL Group retold a story script developed for the wordless picture book, Carl Goes Shopping (Day, 1995). These children produced between 35 and 93 complete and intelligible utterances (M = 73),

although data pertaining to the number of complete and intelligible utterances were unavailable for two participants. Children in the S Group retold a story script developed for the wordless picture book, Pancakes for Breakfast (dePaola, 1978). These children produced between 34 and 96 complete and intelligible utterances (M = 64). All children presented with normal oral motor functioning on the Oral and Speech Motor Control Protocol (Robbins & Klee, 1987) and normal hearing. Normal hearing was confirmed in children in the SL Group in one of two ways. Children passed a hearing screening administered either (a) during the standard evaluation process in the University of Nevada, Reno’s Speech Pathology and Audiology Clinic before being referred for the Tyler et al. (2011) study; or (b) by the Washoe County School District. For children referred from the school district, the referral source confirmed that the child had passed a hearing screening. Normal hearing was confirmed in children in the S Group by positive responses during a hearing screening administered as part of the original Macrae et al. (2014) study. All but one participant (in the SL Group) presented with ageappropriate receptive vocabulary, confirmed by a score within the typical range (≤1 SD below the mean) on the Peabody Picture Vocabulary Test—III (PPVT–III; Dunn & Dunn, 1997). Descriptive statistics and group comparisons for the participant characteristics are presented in Table 1.

Word Lists As part of the earlier studies, participants attended one or two assessment sessions to determine eligibility and obtain experimental measures. All experimental measures for the present study were obtained from the participants’ single word productions from the standardized tests of articulation/phonology and additional words, transcribed online using IPA broad transcription. Clinically significant distortions, for example, dentalization and lateralization of /s/, were also transcribed. Productions that were not clear during the assessment sessions were checked later using the audio recordings. All words with bound morphemes were Table 1. Descriptive statistics and group comparisons for participant characteristics

Measure Age (months) Artic. SS PCC Lang. SS MLUm PPVT–III SS

SL Group

S Group

M

M

SD

SD

54.00 5.04 56.23 7.77 63.71 11.83 67.54 3.43 46.64 14.22 56.05 12.91 67.53 15.07 101.46 11.36 2.97 0.68 5.46 1.55 96.53 9.79 107.15 10.87

t –0.91 –1.16 –1.82 –6.64 –5.36 –2.72

df

p

26 .369 15.33 .264 26 .080 26 < .001 15.90 < .001 26 .011

Note. Artic. SS = articulation/phonology test standard score; PCC = percent consonants correct; Lang. SS = language test standard score; MLUm = mean length of utterance in morphemes; PPVT–III SS = Peabody Picture Vocabulary Test—III standard score (Dunn & Dunn, 1997).

Macrae & Tyler: Speech Abilities in Preschool Children

305

omitted from the analyses for both groups. Children in the SL Group had expressive language disorders characterized by difficulties using morphological structures, as revealed by low scores on the SPELT–P2. By removing words with bound morphemes, we could consider production errors phonological and not morphological in nature. In an effort to maintain consistency in the makeup of the word lists for the two groups, we also removed words with bound morphemes from the S Group’s wordlist. There were 67 and 99 words remaining that formed the analysis sets for the SL and S Groups, respectively. These word lists are found in Appendix A. Before possible differences in severity of SSD and/or error pattern use could be attributed to language status and not to differences in the characteristics of the words in the different wordlists, the wordlists were compared for phonetic and structural complexity using the Word Complexity Measure (WCM; Stoel-Gammon, 2010). WCM assigns an ordinal level score to a word on the basis of three levels of complexity: word patterns (number of syllables and stress patterns), syllable structures, and sound classes. A Mann– Whitney U test was calculated to compare the lists in WCM. The wordlists were also compared for numbers of syllables, consonant clusters, and late-8 consonants (Shriberg, 1993) using independent samples t tests. All tests revealed nonsignificant differences between the lists, thereby confirming similar levels of phonetic and structural complexity.

Error Patterns Each single word production was coded for error pattern use using Preston’s coding rules (Preston, 2008; Preston & Edwards, 2010). These coding rules are found in Appendix B. Participants’ entire productions were analyzed, not just the target sounds scored by each standardized test. First, error patterns describing any changes in the target word’s syllable structure were listed. Then, each speech sound error was broken down into its component error patterns affecting the target consonant’s place and manner of articulation and voicing. For example, if the target word shoe was produced as [du], this would reflect three component patterns: palatal fronting affecting place of articulation (/Su/ → [su]), stopping of fricatives affecting manner of articulation (/su/ → [tu]), and prevocalic voicing (/tu/ → [du]). As per Preston’s rules, if alternative error patterns could explain a change in the target consonant’s place or manner of articulation or voicing, typical error patterns were chosen over atypical patterns. For example, if the target word duck was produced as [gÃk], this could be coded as either backing or velar assimilation. In this case, velar assimilation, a typical error pattern, was chosen over backing, an atypical error pattern. Second, each error pattern was further categorized as an omission, substitution, or distortion pattern, and as reflecting either typical or atypical development. Omission patterns were those that involved the omission of one or more syllables or speech sounds from the target word (e.g., weak syllable deletion, final consonant deletion, and cluster reduction). Substitution patterns were those that involved

306

the substitution of one speech sound for the target sound (e.g., velar fronting, prevocalic voicing, and deaffrication). Distortion patterns were those that involved common clinically significant variations in target speech sounds (e.g., lateralized /s/, [sl], and dentalized /s/, [sw ]). The categorization of error patterns as reflecting either typical or atypical development was based on Preston’s rules (Preston, 2008; Preston & Edwards, 2010), with a few additions. Whereas Preston considered a lateral lisp a distortion pattern, we categorized it as both a distortion and an atypical pattern for the present study. Preston did not refer to bilabial fricatives in his studies. These were categorized as both distortion and atypical patterns for the present study. Preston considered “fricative replacing stop,” “liquid replacing glide,” and “gliding of intervocalic consonants (other than fricative or liquid)” atypical patterns. As part of the present study, “fricative replacing liquid or glide,” “liquid replacing fricative,” and “gliding of prevocalic consonants” were also included as atypical patterns. Third, for each participant, the number of occurrences of error patterns in each of the five categories (i.e., omission, substitution, distortion, typical, and atypical) was divided by the total number of consonants attempted, which varied across participants (n = 185 to 195 for children in the SL Group; n = 245 for all children in the S Group). This yielded a proportion of each type of error pattern used per consonant attempted for each participant, as per Preston and Edwards (2010).

Reliability Interrater agreement was assessed for two participants from each group (14% of the participants), selected at random. Agreement was calculated for IPA broad transcription of consonant productions and clinically significant distortions as well as the categorization of error patterns. Transcription agreement, calculated between the original and a second transcriber, was 91% for the SL group and 87% for the S group. Transcribers were either the first or second author or a graduate student in communication science and disorders trained in IPA transcription. Agreement for the categorization of error patterns, calculated between the original analyst (the first author) and a graduate student trained in the identification of error patterns, was 87% for the SL group and 94% for the S group.

Results The two groups were initially compared in the participant characteristic measures using independent samples t tests, with an alpha level of p < .05. These included age, standard score from the tests of articulation/phonology, PCC, standard score from the tests of language, MLUm, and standard score from the test of receptive vocabulary. Results of the t tests are shown in Table 1 and revealed no significant group differences in age, standard score from the tests of articulation/phonology, and PCC, but significant group differences in standard score from the language

Language, Speech, and Hearing Services in Schools • Vol. 45 • 302–313 • October 2014

tests, MLUm, and standard score from the test of receptive vocabulary. The two groups were then compared in measures of error pattern use, including the number used per consonant attempted of each of the five different types of error patterns (omission, substitution, distortion, typical, and atypical) and total error patterns, using independent samples t tests. Descriptive statistics and group comparisons for the experimental measures are presented in Table 2. Results of the t tests revealed no significant group difference in total error patterns used per consonant attempted, thus confirming the similar levels of severity of SSD across the groups. Results also revealed significant group differences in omission and distortion error pattern use per consonant attempted. There were no significant group differences in substitution error pattern use and overall typical and atypical error pattern use per consonant attempted. Children in the SL Group showed significantly more frequent use of omission error patterns and significantly less frequent use of distortion error patterns, in comparison with children in the S Group. There was a trend of less frequent use of substitution error patterns in children in the SL Group in comparison with children in the S Group (p = .093), which may have been significant given a larger sample size. Effect sizes, measured using Cohen’s d (Cohen, 1988), were large for the group differences in omission and distortion error pattern use and medium for the difference in substitution error pattern use.

Discussion The purpose of this study was to compare children with co-occurring SSD and LI with those with SSD only in their numbers of speech sound errors and types of error patterns using the standard score from different tests of articulation/phonology, PCC, and the number of omission, substitution, distortion, typical, and atypical error patterns

Table 2. Descriptive statistics and group comparisons for experimental measures. SL Group

S Group

Measure

M

SD

M

Omission Substitution Distortion Typical Atypical Total

.19 .32 0 .46 .08 .54

.11 .06 0 .12 .05 .13

.06 .40 .04 .43 .07 .50

SD .05 .15 .05 .14 .07 .18

t

df

p

d

4.18 19.82 < .001 1.55 –1.79 15.35 .093 0.70 –2.63 12.06 .022 1.03 0.50 26 .622 0.68 26 .506 0.69 26 .495

Note. Omission = number of omission error patterns used per consonant attempted; substitution = number of substitution error patterns used per consonant attempted; distortion = number of distortion error patterns used per consonant attempted; typical = number of developmentally typical error patterns used per consonant attempted; atypical = number of developmentally atypical error patterns used per consonant attempted; total = total number of error patterns used per consonant attempted.

used per consonant attempted. Whereas participants in the SL Group were originally selected for the Tyler et al. (2011) study on the basis of the presence of SSD and LI, participants in the S Group were originally selected for the Macrae et al. (2014) study based only on the presence of SSD and age-appropriate receptive vocabulary; overall language ability was not a selection criterion. For the present study, all children in the S Group were required to score within the typical range on a standardized test of language and a subtest assessing the use of morphological structures. In the present study, the SL Group performed significantly more poorly than the S Group in three different measures of language abilities. These groups, therefore, represented children with co-occurring SSD and LI and children with SSD only with similar ages and levels of severity of SSD and differing language abilities. The two groups, although not recruited for the present study, represented a unique opportunity to compare speech abilities in these children. The two groups did not differ in their numbers of speech sound errors, as revealed by similar standard scores on the tests of articulation/phonology, PCC scores, and overall error pattern use. This finding is in contrast to other studies that found more speech sound errors in children with co-occurring SSD and LI in comparison with children with SSD only (Nathan et al., 1998, 2004; Sices et al., 2007). Part of the reason for these contrasting findings may lie in methodological differences across the studies. For example, Nathan et al. (1998) examined speech errors in imitative tasks, whereas the present study involved several measures of spontaneous speech production. This does not, however, completely account for the differences. Nathan et al. (2004) was more similar to the present study in that the authors included several measures of speech production, one of which was a spontaneous task, yet these authors also found group differences in severity not seen in the present study. The contrasting findings are difficult to interpret, but they suggest that, in some children, language competence may not be related to severity of SSD. Children with co-occurring SSD and LI may not always be more severely impaired than children with SSD only. Furthermore, Ruscello et al. (1991) found that children with severe SSDs did not present with poorer language skills than children with mild-to-moderate SSDs. The present study’s finding of no significant group difference in the severity of SSD is useful because any group differences in error pattern use can be attributed to the presence or absence of co-occurring LI and not to differences in severity of SSD (see Ruscello et al.). The two groups showed significant differences in omission and distortion error pattern use. There were no significant differences in substitution, typical, and atypical error pattern use. Children in the SL Group used significantly more omission error patterns, demonstrated significantly fewer distortion error patterns, and showed a trend of fewer substitution error patterns, in comparison with children in the S Group. These findings reveal that, although these two groups of children showed similar numbers of speech

Macrae & Tyler: Speech Abilities in Preschool Children

307

sound errors, they showed different types of error patterns that cannot be attributed to differences in severity of SSD. Furthermore, the SL Group’s omission patterns cannot be attributed to differences in the characteristics of the words in the two datasets. First, words with bound morphemes were omitted from the analyses. Second, the different wordlists were comparable in terms of phonetic and structural complexity. More frequent use of omission error patterns by the children with co-occurring SSD and LI supports Shriberg et al.’s (2005) contention that omission patterns reflect a cognitive-linguistic processing deficit. Shriberg et al. suggested that frequent use of omission patterns reflects a more compromised linguistic system characterized by absent phonological representations for target sounds. A predominance of substitution and distortion error patterns, on the other hand, may reflect a less compromised linguistic system characterized by incorrect but present phonological representations for target sounds. The two groups showed very similar distortion, typical, and atypical error pattern use to children with SSDs in another study (Preston & Edwards, 2010). Children in the SL and S Groups had similar ages to children in the Preston and Edwards (2010) study (M = 54, 57, 55 months, respectively). Children in the SL and S Groups also had similar levels of severity of SSD to children in the Preston and Edwards study (mean PCC = 47, 56, 48, respectively). With regard to error patterns, children in the SL and S Groups showed similar use of the following, in comparison with children in the Preston and Edwards study: distortion (M = .05, 0, .03, respectively), typical (M = .45, .46, .45, respectively), and atypical (M = .07, .08, .07, respectively). No significant group difference in atypical pattern use in the present study suggests that atypical patterns may not reflect a more broadly impaired linguistic system. Rather, given their relationship with poor phonological representations, PA, decoding, and spelling skills (Dodd et al., 1989; Leitao et al., 1997, 2000; Leitao & Fletcher, 2004; Preston & Edwards, 2010; Rvachew et al., 2007), they are thought to reflect a more specific phonological processing deficit characterized by an impaired ability to abstract and use phonological rules (Dodd & Lacano, 1989; Leitao et al., 1997).

Clinical Implications Leonard (1973) proposed that children who use atypical error patterns be given priority for speech intervention as they are not likely to normalize without it. The same could be said for children with co-occurring SSD and LI who show frequent use of omission error patterns, given their more compromised linguistic systems and their risk of developing literacy disorders. Furthermore, omission error patterns are associated with poor speech normalization. Shriberg et al. (1994) found that, in the presence and absence of intervention, speech normalization in children with SSD was related to their use of omission error patterns. Those children whose speech did not normalize showed larger proportions of omission patterns than substitution patterns. Children with co-occurring SSD and LI will benefit

308

from an approach that targets both deficits. Alternating speech and language goals on a weekly basis leads to superior language gains and similar phonological gains in children with co-occurring deficits in comparison with approaches that target each domain in blocks and an approach that targets both domains in the same session (Tyler et al., 2003). Target selection for phonological intervention might involve prioritizing these children’s omission patterns in an effort to establish phonological representations for omitted speech sounds. This is consistent with a cycles approach to phonological intervention, which involves targeting error patterns in a cyclical fashion (see Prezas & Hodson, 2010). Prezas and Hodson (2010) advocated for targeting omission patterns, including syllable and consonant omissions, before targeting substitution patterns. Initially, treatment might involve training children to mark the sounds without concern for accuracy of production. Once children learn to consistently mark speech sounds that were previously omitted, treatment would then shift to training accurate production of the target sounds. When working with children with a predominance of substitution patterns, SLPs might take a slightly different approach. Target selection might not need to include an initial explicit focus on establishing phonological representations for omitted sounds. Rather, treatment should focus on improving the accuracy of present but incorrect phonological representations by training accurate production of target sounds.

Limitations and Future Directions One limitation associated with the present study involves the comparison of two groups that were originally selected for separate studies and were administered different test protocols, including different standardized tests of articulation/phonology and language. This limitation was mitigated in several ways. First, although children in the two groups produced words from different wordlists, these wordlists showed comparable levels of phonetic and structural complexity. Furthermore, words with bound morphemes were removed from the wordlists for children in both groups, thereby ensuring their production errors were phonological and not morphological in nature. Second, although different language tests were administered to the two groups, there are some similarities between the SPELT–P2, which assesses a child’s use of morphological and syntactical structures and pronouns, and the CELF–P2, which assesses overall receptive and expressive language abilities. Like the SPELT–P2, the CELF–P2 assesses a child’s use of morphological and syntactical structures and pronouns by way of the Word Structure subtest. All children in the S Group scored within the typical range for their age on this subtest, thus confirming age-appropriate skills in these areas. Third, children whose standardized language test scores fell within the typical range for their age were excluded from the SL Group. Children whose standardized language test scores fell outside the typical range for their age were excluded from the S Group. Together with the scores on the tests of articulation/phonology, this confirms that the two

Language, Speech, and Hearing Services in Schools • Vol. 45 • 302–313 • October 2014

groups consisted of children with co-occurring SSD and LI and children with SSD only. Fourth, no significant group differences in numbers of speech sound errors and significant group differences in measures of language (including MLUm, which was calculated in much the same way for both groups) confirmed similar speech production abilities yet different language abilities in the two groups of children. Although the limitation of different test protocols is mitigated to some extent, caution is required when interpreting results from this post hoc comparison of two relatively small groups of participants. The present study did not include a measure of PA, which is known to be related to atypical error pattern use (Leitao et al., 1997, 2000; Leitao & Fletcher, 2004; Preston & Edwards, 2010; Rvachew et al., 2007). The two groups of participants, therefore, may have differed in their PA abilities. Although there was no group difference in atypical pattern use, it nevertheless calls for caution when concluding that atypical pattern use is not associated with co-occurring LI in children with SSD. For example, superior PA skills and inferior language skills may have had competing effects on atypical pattern use in the children with co-occurring SSD and LI, although these children were much more likely to have had inferior PA skills (see Lewis et al., 2011; Nathan et al., 2004; Sices et al., 2007). Future research might involve comparing atypical pattern use in children with cooccurring SSD and LI and children with SSD only with similar levels of severity of SSD and similar PA skills. Another limitation of the present study is that speech sound accuracy was based only on participants’ consonant productions. Preston and Edwards (2010) also noted this as a limitation in their study. These two groups did not differ in their numbers of consonant errors; however, there may have been a group difference in vowel accuracy. The findings of this study may have important implications for early identification of reading problems in children. Although increased omission and atypical error pattern use may each reflect a unique cognitive-linguistic processing deficit, both appear to be associated with an increased risk of reading problems. Frequent atypical error pattern use, thought to reflect a phonological processing deficit, has already been linked to reading and spelling problems (Leitao et al., 1997, 2000; Leitao & Fletcher, 2004). In the present study, children with co-occurring SSD and LI (i.e., those at particular risk of developing reading problems; Peterson et al., 2009), showed frequent omission error pattern use. Foy and Mann (2012) found a significant correlation between omission error pattern use and nonword reading abilities in kindergarten-aged children without SSDs, although the correlation was low (r = –.22). Research is required to determine whether increased omission and atypical error pattern use in younger children with SSD (i.e., younger than 3 years old) is predictive of later reading problems. Identification rates of speech-language impairments in preschool children are low (Tomblin et al., 1997), and speech production abilities are the main determinant of whether a parent is informed of an impairment (Tomblin, 1996). Speech error patterns thought to reflect underlying

cognitive-linguistic processing deficits (e.g., omission error patterns) may hold potential for early identification of children at risk of co-occurring SSD and LI (and, therefore, reading problems) in part because they may be relatively easy for parents, teachers, and SLPs to identify at a young age. If young children with SSD who show frequent use of these patterns are shown to be at risk, then they will need to be monitored carefully and regularly and their parents and teachers provided with preventative speech-language and PA stimulation strategies to use at home and at preschool.

Conclusions Children with co-occurring SSD and LI showed similar numbers of speech sound errors but different types of error patterns than children with SSD only. More frequent use of omission error patterns and less frequent use of distortion error patterns by children with co-occurring SSD and LI support Shriberg et al.’s (2005) conclusions: frequent omission pattern use may be associated with a more compromised linguistic system characterized by absent phonological representations for target sounds. Frequent distortion pattern use may reflect a less compromised system characterized by partially correct phonological representations. These findings may have important implications for early identification of children with co-occurring SSD and LI, who are at risk of later reading problems. 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.

Acknowledgments This research is based, in part, on data from a dissertation submitted by the first author in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Speech Pathology from the University of Nevada, Reno. This research was initially presented at the annual convention of the American SpeechLanguage-Hearing Association, November 2011, San Diego, CA.

References Bankson, N. W., & Bernthal, J. E. (1990). Bankson–Bernthal Test of Phonology. Austin, TX: Pro-Ed. Bird, J., Bishop, D. V. M., & Freeman, N. H. (1995). Phonological awareness and literacy development in children with expressive phonological impairments. Journal of Speech and Hearing Research, 38, 446–462. Retrieved from http://jslhr.pubs.asha.org Bishop, D. V. M., & Adams, C. (1990). A prospective study of the relationship between specific language impairment, phonological disorders and reading retardation. The Journal of Child Psychology and Psychiatry, 31, 1027–1050. doi:10.1111/j.1469-7610. 1990.tb00844.x Broomfield, J., & Dodd, B. (2004). Children with speech and language disability: Caseload characteristics. International Journal of Language and Communication Disorders, 39, 303–324. doi:10.1080/13682820310001625589 Campbell, T., Dollaghan, C., Needleman, H., & Janosky, J. (1997). Reducing bias in language assessment: Processing-dependent measures. Journal of Speech, Language, and Hearing Research, 40, 519–525.

Macrae & Tyler: Speech Abilities in Preschool Children

309

Campbell, T. F., Dollaghan, C. A., Rockette, H. E., Paradise, J. L., Feldman, H. M., Shriberg, L. D., . . . Kurs-Lasky, M. (2003). Risk factors for speech delay of unknown origin in 3-year-old children. Child Development, 74, 346–357. doi:10.1111/14678624.7402002 Catts, H. W. (1989). Phonological processing deficits and reading disabilities. In A. G. Kamhi & H. W. Catts (Eds.), Reading disabilities: A developmental language perspective (pp. 101–132). Boston, MA: College-Hill Press. Catts, H. W. (1993). The relationship between speech-language impairments and reading disabilities. Journal of Speech and Hearing Research, 36, 948–958. Retrieved from http://jslhr. pubs.asha.org Catts, H. W., Adlof, S. M., Hogan, T. P., & Weismer, S. E. (2005). Are specific language impairment and dyslexia distinct disorders? Journal of Speech, Language, and Hearing Research, 48, 1378–1396. Catts, H. W., Kamhi, A. G., & Adlof, S. M. (2012). Defining and classifying reading disabilities. In A. G. Kamhi & H. W. Catts (Eds.), Language and reading disabilities (3rd ed., pp. 45–111). Boston, MA: Pearson. Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Hillsdale, NJ: Erlbaum. Conti-Ramsden, G., & Botting, N. (2001). Psycholinguistic markers for specific language impairment (SLI). The Journal of Child Psychology and Psychiatry, 42, 741–748. Dawson, J., Stout, C., Eyer, J., Tattersall, P., Fonkalsrud, J., & Croley, K. (2005). Structured Photographic Expressive Language Test—Preschool (2nd ed.). DeKalb, IL: Janelle. Day, A. (1995). Carl goes shopping. New York, NY: Farrar, Straus & Giroux. de Bree, E., Rispens, J., & Gerrits, E. (2007). Non-word repetition in Dutch children with (at risk of) dyslexia and SLI. Clinical Linguistics & Phonetics, 21, 935–944. dePaola, T. (1978). Pancakes for breakfast. Orlando, FL: Harcourt. Dodd, B. (2005). Differential diagnosis and treatment of children with speech disorder (2nd ed.). London, United Kingdom: Whurr. Dodd, B., Holm, A., Crosbie, S., & McCormack, P. (2005). Differential diagnosis of phonological disorders. In B. Dodd (Ed.), Differential diagnosis and treatment of children with speech disorder (2nd ed.; pp. 44–70). London, United Kingdom: Whurr. Dodd, B., & Lacano, T. (1989). Phonological disorders in children: Changes in phonological process use during treatment. International Journal of Language & Communication Disorders, 24, 333–351. doi:10.3109/13682828909019894 Dodd, B., Leahy, J., & Hambly, G. (1989). Phonological disorders in children: Underlying cognitive deficits. British Journal of Developmental Psychology, 7, 55–71. doi:10.1111/j.2044835X.1989.tb00788.x Dollaghan, C., & Campbell, T. F. (1998). Nonword repetition and child language impairment. Journal of Speech, Language, and Hearing Research, 41, 1136–1146. Donegan, P. J., & Stampe, D. (1979). The study of natural phonology. In D. A. Dinnsen (Ed.), Current approaches to phonological theory (pp. 126–173). Bloomington, IN: Indiana University Press. Dunn, L. M., & Dunn, D. M. (1997). Peabody Picture Vocabulary Test—III. Circle Pines, MN: AGS. Foy, J. G., & Mann, V. A. (2012). Speech production deficits in early readers: Predictors of risk. Reading and Writing, 25, 799–830. doi:10.1007/s11145-011-9300-4 Gathercole, S. E., & Baddeley, A. D. (1990). Phonological memory deficits in language disordered children: Is there a causal connection? Journal of Memory and Language, 29, 336–360.

310

Goldman, R., & Fristoe, M. (2000). Goldman Fristoe Test of Articulation (2nd ed.). Circle Pines, MN: AGS. Kamhi, A. G., & Catts, H. W. (1986). Toward an understanding of developmental language and reading disorders. Journal of Speech and Hearing Disorders, 51, 337–347. Kamhi, A. G., & Catts, H. W. (2012). Language and reading disabilities (3rd ed.). Boston, MA: Allyn & Bacon. Leahy, J., & Dodd, B. (1987). The development of disordered phonology: A case study. Language and Cognitive Processes, 2, 115–132. doi:10.1080/01690968708406353 Leitao, S., & Fletcher, J. (2004). Literacy outcomes for students with speech impairment: Long-term follow-up. International Journal of Language & Communication Disorders, 39, 245–256. doi:10.1080/13682820310001619478 Leitao, S., Fletcher, J., & Hogben, J. (2000). Speech impairment and literacy difficulties: Underlying links. The Australian Educational and Developmental Psychologist, 17, 63–75. Retrieved from http://journals.cambridge.org/action/displayJournal? jid=EDP Leitao, S., Hogben, J., & Fletcher, J. (1997). Phonological processing skills in speech and language impaired children. International Journal of Language & Communication Disorders, 32, 91–111. Leonard, L. B. (1973). The nature of deviant articulation. Journal of Speech and Hearing Disorders, 38, 156–161. Retrieved from http://jslhr.pubs.asha.org Lewis, B. A., Avrich, A. A., Freebairn, L. A., Taylor, H. G., Iyengar, S. K., & Stein, C. M. (2011). Subtyping children with speech sound disorders by endophenotypes. Topics in Language Disorders, 31, 112–127. doi:10.1097/TLD.0b013e318217b5dd Lewis, B. A., & Freebairn, L. (1992). Residual effects of preschool phonology disorders in grade school, adolescence, and adulthood. Journal of Speech and Hearing Research, 35, 819–831. Retrieved from http://jslhr.pubs.asha.org Lewis, B. A., O’Donnell, B., Freebairn, L. A., & Taylor, H. G. (1998). Spoken language and written expression—Interplay of delays. American Journal of Speech-Language Pathology, 7, 77–84. Retrieved from http://ajslp.pubs.asha.org Macrae, T., Tyler, A. A., & Lewis, K. E. (2014). Lexical and phonological variability in preschool children with speech sound disorder. American Journal of Speech-Language Pathology, 23, 27–35. doi:10.1044/1058-0360(2013/12-0037) Mann, V. A., & Foy, J. G. (2007). Speech development patterns and phonological awareness in preschool children. Annals of Dyslexia, 57, 51–74. doi:10.1007/s11881-007-0002-1 Miller, J., & Chapman, R. (2000). SALT: Systematic Analysis of Language Transcripts [Computer software]. Madison, WI: University of Wisconsin. Nathan, L., Stackhouse, J., & Goulandris, N. (1998). Speech processing abilities in children with speech vs speech and language difficulties. International Journal of Language & Communication Disorders, 33, 457–462. doi:10.3109/13682829809179468 Nathan, L., Stackhouse, J., Goulandris, N., & Snowling, M. J. (2004). The development of early literacy skills among children with speech difficulties: A test of the “critical age hypothesis.” Journal of Speech, Language, and Hearing Research, 47, 377–391. doi:10.1044/1092-4388(2004/031) Peterson, R. L., Pennington, B. F., Shriberg, L. D., & Boada, R. (2009). What influences literacy outcome in children with speech sound disorder? Journal of Speech, Language, and Hearing Research, 52, 1175–1188. doi:10.1044/1092-4388(2009/08-0024) Preston, J. (2008). Phonological processing and speech production in preschoolers with speech sound disorders (Unpublished doctoral dissertation). Syracuse University, Syracuse, NY.

Language, Speech, and Hearing Services in Schools • Vol. 45 • 302–313 • October 2014

Preston, J., & Edwards, M. L. (2010). Phonological awareness and types of sound errors in preschoolers with speech sound disorders. Journal of Speech, Language, and Hearing Research, 53, 44–60. doi:10.1044/1092-4388(2009/09-0021) Prezas, R. F., & Hodson, B. W. (2010). The cycles phonological remediation approach. In A. Lynn Williams, S. McLeod, & R. J. McCauley (Eds.), Interventions for speech sound disorders in children (pp. 137–157). Baltimore, MD: Brookes. Robbins, J., & Klee, T. (1987). Clinical assessment of oropharyngeal motor development in young children. Journal of Speech and Hearing Disorders, 52, 271–277. Ruscello, D. M., St. Louis, K. O., & Mason, N. (1991). Schoolaged children with phonologic disorders: Coexistence with other speech/language disorders. Journal of Speech and Hearing Research, 34, 236–242. Retrieved from http://jslhr.pubs.asha.org Rvachew, S., Chiang, P.-Y., & Evans, N. (2007). Characteristics of speech errors produced by children with and without delayed phonological awareness skills. Language, Speech, and Hearing Services in Schools, 38, 60–71. doi:10.1044/0161-1461 (2007/006) Semel, E., Wiig, E., & Secord, W. (2004). Clinical Evaluation of Language Fundamentals—Preschool (2nd ed.). San Antonio, TX: The Psychological Corporation. Shriberg, L. D. (1993). Four new speech and prosody-voice measures for genetics research and other studies in developmental phonological disorders. Journal of Speech and Hearing Research, 36, 105–140. Shriberg, L. D., & Kwiatkowski, J. (1982). Phonological disorders III: A procedure for assessing severity of involvement. Journal of Speech and Hearing Disorders, 47, 256–270. Retrieved from http://jslhr.pubs.asha.org Shriberg, L. D., & Kwiatkowski, J. (1994). Developmental phonological disorders I: A clinical profile. Journal of Speech and Hearing Research, 37, 1100–1126. Shriberg, L. D., Kwiatkowski, J., & Gruber, F. A. (1994). Developmental phonological disorders II: Short-term speech-sound normalization. Journal of Speech and Hearing Research, 37, 1127–1150. Retrieved from http://jslhr.pubs.asha.org Shriberg, L. D., Lewis, B. A., Tomblin, J. B., McSweeny, J. L., Karlsson, H. B., & Scheer, A. R. (2005). Toward diagnostic and phenotype markers for genetically transmitted speech delay. Journal of Speech, Language, and Hearing Research, 48, 834–852. doi:10.1044/1092-4388(2005/058) Shriberg, L. D., Tomblin, J. B., & McSweeny, J. L. (1999). Prevalence of speech delay in 6-year-old children and comorbidity

with language impairment. Journal of Speech, Language, and Hearing Research, 42, 1461–1481. Retrieved from http://jslhr. pubs.asha.org Sices, L., Taylor, H. G., Freebairn, L., Hansen, A., & Lewis, B. (2007). Relationship between speech-sound disorders and early literacy skills in preschool-age children: Impact of comorbid language impairment. Journal of Developmental & Behavioral Pediatrics, 28, 438–447. doi:10.1097/DBP.0b013e31811ff8ca Skebo, C. M., Lewis, B. A., Freebairn, L. A., Tag, J., Avrich Ciesla, A., & Stein, C. M. (2013). Reading skills of students with speech sound disorders at three stages of literacy development. Language, Speech, and Hearing Services in Schools, 44, 360–373. doi:10.1044/0161-1461(2013/12-0015) Stampe, D. (1969).The acquisition of phonetic representation. Chicago Linguistic Society, 5, 443–454. Stoel-Gammon, C. (2010). The Word Complexity Measure: Description and application to developmental phonology and disorders. Clinical Linguistics & Phonetics, 24, 271–282. Stoel-Gammon, C. (2011). Relationships between lexical and phonological development in young children. Journal of Child Language, 38, 1–34. doi:10.1017/S0305000910000425 Tomblin, J. B. (1996, June). The big picture of SLI: Epidemiology of SLI. Paper presented at the Symposium on Research in Child Language Disorders, Madison, WI. Tomblin, J. B., Records, N. L., Buckwalter, P., Zhang, X., Smith, E., & O’Brien, M. (1997). Prevalence of specific language impairment in kindergarten children. Journal of Speech, Language, and Hearing Research, 40, 1245–1260. Tyler, A. A., Gillon, G., Macrae, T., & Johnson, R. L. (2011). Direct and indirect effects of stimulating phoneme awareness vs. other linguistic skills in preschoolers with co-occurring speech and language impairments. Topics in Language Disorders, 31, 128–144. doi:10.1097/TLD.0b013e318217d473 Tyler, A. A., Lewis, K. E., Haskill, A., & Tolbert, L. C. (2003). Outcomes of different speech and language goal attack strategies. Journal of Speech, Language, and Hearing Research, 46, 1077–1094. doi:10.1044/1092-4388(2003/085) Wagner, R. K., & Torgesen, J. K. (1987). The nature of phonological processing and its causal role in the acquisition of reading skills. Psychological Bulletin, 101, 192–212. Wellman, R. L., Lewis, B. A., Freebairn, L. A., Avrich, A. A., Hansen, A. J., & Stein, C. M. (2011). Narrative ability of children with speech sound disorders and the prediction of later literacy skills. Language, Speech, and Hearing Services in Schools, 42, 561–579. doi:10.1044/0161-1461(2011/10-0038)

Macrae & Tyler: Speech Abilities in Preschool Children

311

Appendix A Wordlists SL Group Wordlist house telephone spoon wagon banana quack watch car carrot feather bath thumb frog slide elephant rain jump you umbrella tongue five girl teeth S Group Wordlist cat candy boat cow wagon hat lamp carrot bus sun fire sled star flag elephant butterfly pig rope teeth them chair patch crayon vest jam cage tub chief vacuum hammer that bathe eel

312

tree cup girl shovel zipper yellow plane blue orange this ring brush green five boat parrot bridge slippery birthday zebra kangaroo witch

window knife ball monkey duck vacuum lamp rabbit chair bathtub finger drum clown shark helicopter vacuum thank slide cake fish dinosaur ladybug

gate dog goat crab cake rabbit radio lion seal thumb shoe snake train telescope kangaroo Santa Claus bat duck sheep mother church yellow meow stove judge zoo knob zebra wash yes thing breathe ring

cup bed gun coat knife balloon rain leaf fish mouth clown milk hand dinosaur umbrella book nose dish this feather watch yard van dive bridge zipper juice shovel drive thank bath lathe king

Language, Speech, and Hearing Services in Schools • Vol. 45 • 302–313 • October 2014

Appendix B Coding of error patterns (Preston, 2008; Preston & Edwards, 2010) Typical Changes Typical omission errors: final consonant deletion, typical /s/ cluster reduction (/s/ omitted), typical liquid cluster reduction (liquid omitted), typical glide cluster reduction (glide omitted), nasal cluster reduction, segment coalescence, consonant sequence reduction (across syllable boundary), weak syllable deletion, syllable coalescence. Typical substitution errors: palatal fronting, velar fronting, labialization of front sounds, alveolarization of front sounds, vocalization of liquids, gliding of liquids, gliding of intervocalic fricatives, stopping of fricatives and affricates, deaffrication, affrication of fricatives, initial voicing, final devoicing, metathesis, assimilation (velar, palatal, nasal, liquid, fricative; either partial or complete). Typical distortion errors: interdentalization/dentalization of /s, z/, labialization of /r/. Atypical Changes Atypical omission errors: atypical /s/ cluster reduction (stop or nasal omitted), atypical liquid cluster reduction (stop or fricative omitted), atypical glide cluster reduction (stop omitted), initial (singleton) consonant deletion, intervocalic consonant deletion, strong syllable deletion. Atypical substitution errors: backing to velars, palatalization, glide interchange, liquid interchange, glottal replacement, denasalization, nasalization, fricative replacing stop (or liquid or glide),* liquid replacing glide (or fricative),* tetism, gliding of (prevocalic and)* intervocalic consonants (other than fricative or liquid), stopping of liquids or glides, initial/prevocalic devoicing, final voicing. Atypical distortion errors: lateralization of sibilants, bilabial fricative.* Other atypical errors: addition of consonants, vowels, or syllables; migration of a segment to a different position. *These patterns were added for the present study.

Macrae & Tyler: Speech Abilities in Preschool Children

313

Copyright of Language, Speech & Hearing Services in Schools is the property of American Speech-Language-Hearing Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.