Realizations of consonant clusters by children with phonological impairment

Simulating Speech Error Patterns Across Languages and Different Datasets

Children's speech acquisition is influenced by universal and language-specific forces. Some speech error patterns (or phonological processes) in children's speech are observed in many languages, but the same error pattern may have different effects in different languages. We aimed to explore phonological effects of the same speech error patterns across different languages, target audiences and discourse modes, using a novel method for large-scale corpus investigation. As an additional aim, we investigated the face validity of five different phonological effect measures by relating them to subjective ratings of assumed effects on intelligibility, as provided by practicing speech-language pathologists. Six frequently attested speech error patterns were simulated in authentic corpus data: backing, fronting, stopping, /r/-weakening, cluster reduction and weak syllable deletion-each simulation resulting in a "misarticulated" version of the original corpus. Phonological effects were quantified using five separate metrics of phonological complexity and distance from expected target forms. Using Swedish child-speech data as a reference, phonological effects were compared between this reference and a) child speech in Norwegian and English, and b) data representing different modes of discourse (spoken/written) and target audiences (adults/children) in Swedish. Of the speech error patterns, backing-the one atypical pattern of those included-was found to cause the most detrimental effects, across languages as well as across modes and speaker ages. However, none of the measures reflects intuitive rankings as provided by clinicians regarding effects on intelligibility, thus corroborating earlier reports that phonological competence is not translatable into levels of intelligibility.

Phonological characteristics of European and Brazilian Portuguese in children with Speech Sound Disorders

This study aims to describe and compare the phonological characteristics of European Portuguese and Brazilian Portuguese preschool and school age children with Speech Sound Disorders (SSD). Speech samples for the European Portuguese Group (EPG) (n = 13) were collected using Subteste Fonético e Fonológico of Teste Fonético e Fonológico Avaliação da Linguagem Pré-Escolar. For the Brazilian Portuguese Group (BPG) (n = 13) Prova de Nomeação de Fonologia of Teste de Linguagem Infantil ABFW was applied. Different phonological measures were considered. Groups were matched according to sex, age, and percentage of correct consonants (revised). EPG presented more weak syllable deletion (p = .00); absolute index and relative index had a higher number of omissions (p = .003). BPG had more substitutions (p = .004). Intragroup analysis showed differences between groups in the occurrence of phonological processes (p ≤ 0.00). The most occurring was gliding of liquids, cluster reduction and devoicing in both groups; for the absolute index and relative index, the EPG presented differences in omission (p = .003), and the BPG in substitution (p = .002). Results suggested differences between groups in phonological processes occurrence and a relation with the most frequent type of error. These findings may occur due to the variation of phonetic and phonological characteristics between European Portuguese and Brazilian Portuguese in the two phonological tests. Linguistic variations had not directly influenced the measures studied, which characterized SSD. European Portuguese and Brazilian Portuguese children with SSD demonstrated similar characteristics as to the type of errors and phonological processes.

Realisation of grammatical morphemes by children with phonological impairment

The aim of this research was to explore how preschool-aged children with phonological impairment (PI) realise grammatical morphemes across different phonological contexts (i.e. singleton consonant, consonant cluster, syllable), conditions of finiteness and individual morpheme types. Factors accounting for children's realisation of grammatical morphemes were also examined. Eighty-seven Australian English-speaking preschoolers (aged 4-5 years) with PI completed the Children's Assessment of Morphophonology (CHAMP)-an elicited response task-in addition to standardised tests of speech and receptive language. The most challenging grammatical morphemes were finite morphemes (particularly past tense) and grammatical morphemes realised in consonant clusters. The ability to produce consonant clusters in single words significantly accounted for children's ability to realise grammatical morphemes, regardless of whether grammatical morphemes were realised in singleton, consonant cluster or syllable contexts. Realisation of grammatical morphemes by preschoolers with PI is influenced by phonological and morphological factors. The findings have implications regarding the assessment and differential diagnosis of preschoolers with concomitant phonological and language difficulties.

A measure for cluster proximity (MCP) in child speech

The proximity of consonant clusters in child speech is measured in the literature by the proportion of adult-like produced clusters to targeted clusters. With this measure, all clusters that are produced adult-like score 100%, while all others score 0%. Consonant clusters in child speech go through three main developmental stages: omission, reduction, two-member production (as targeted or substituted). Several authors claim that two-member clusters produced as two members should be considered acquired whether realised as targeted or not. In view of all these, a measure is needed that quantitatively differentiates all possible realisations of two-member clusters: omission, reduction, vowel epenthesis, two-member production, distinguishing substituted consonants from adult-like ones. Such a measure is proposed in the present article. To demonstrate its validity, the measure is applied to cluster productions of typically and atypically developing monolingual and bilingual children cross-linguistically. Moreover, it is applied to a bilingual Greek-English child's consonant clusters at age 2;7, when all cluster realisations are present. The aim is for the measure to be used in establishing norms for each stage in cluster development which will, in turn, guide assessment and intervention in phonologically delayed/disordered children.

Polysyllable productions in preschool children with speech sound disorders: Error categories and the Framework of Polysyllable Maturity

PURPOSE

Children with speech sound disorders (SSD) find polysyllables difficult; however, routine sampling and measurement of speech accuracy are insufficient to describe polysyllable accuracy and maturity. This study had two aims: (1) compare two speech production tasks and (2) describe polysyllable errors within the Framework of Polysyllable Maturity.

METHOD

Ninety-three preschool children with SSD from the Sound Start Study (4;0-5;5 years) completed the Polysyllable Preschool Test (POP) and the Diagnostic Evaluation of Articulation and Phonology (DEAP-Phonology).

RESULT

Vowel accuracy was significantly different between the POP and the DEAP-Phonology. Polysyllables were analysed using the seven Word-level Analysis of Polysyllables (WAP) error categories: (1) substitution of consonants or vowels (97.8% of children demonstrated common use), (2) deletion of syllables, consonants or vowels (65.6%), (3) distortion of consonants or vowels (0.0%), (4) addition of consonants or vowels (0.0%), (5) alteration of phonotactics (77.4%), (6) alteration of timing (63.4%) and (7) assimilation or alteration of sequence (0.0%). The Framework of Polysyllable Maturity described five levels of maturity based on children's errors.

CONCLUSIONS

Polysyllable productions of preschool children with SSD can be analysed and categorised using the WAP and interpreted using the Framework of Polysyllable Maturity.

Acquisition of Consonant Clusters and Acceptable Variants in Chinese-Influenced Malaysian English-Speaking Children

PURPOSE

This study investigated consonant cluster acquisition in Chinese-influenced Malaysian English (ChME)-speaking children.

METHOD

This cross-sectional study involved 262 typically developing ChME-speaking children (138 girls, 124 boys) ages 3 to 7 years old. A single-word picture-naming task, which contained 66 words and targeted 32 syllable-initial (SI) and 14 syllable-final (SF) consonant clusters, was administered.

RESULTS

Older children produced more correct productions than younger children, and there was no sex effect for consonant cluster production. SF consonant clusters were more accurate than SI consonant clusters among the younger children. The overall sequence of SI consonant cluster accuracy based on cluster categories from most to least accurate was /s/ + C, C + /w/, C + /j/, C + /l/, and C + /r/, whereas for SF consonant clusters, the order was C + stop, C + /s/, nasal + C, and /l/ + C. Two-element clusters consistently had higher accuracy in comparison to three-element clusters across the age groups. The overall consonant cluster accuracy of the present study showed similar patterns to those found in previous studies of Standard English.

CONCLUSION

The findings of the study will be useful in the assessment of consonant cluster production of ChME-speaking children.

Content coverage of single-word tests used to assess common phonological error patterns

PURPOSE

This review evaluated whether 9 single-word tests of phonological error patterns provide adequate content coverage to accurately identify error patterns that are active in a child's speech.

METHOD

Tests in the current study were considered to display sufficient opportunities to assess common phonological error patterns if they provided at least 4 opportunities for each of 11 error patterns. The target phonemes for these error patterns had to occur as singletons (except for final consonant deletion and cluster reduction) and in stressed syllables (except for weak syllable deletion). Error patterns for which positional asymmetries have been documented (velar fronting, stopping of fricatives and affricates, and cluster reduction) required 4 opportunities in both word-initial and word-final position to meet the study's criterion.

RESULTS

None of the tests provided 4 opportunities for every error pattern, the criterion level used in this study. Error patterns that tended to be underrepresented across tests included weak syllable deletion, reduction of word-final clusters, fronting of velars, gliding of liquids, and deaffrication.

CONCLUSION

This review will allow clinicians to gain a deeper understanding of the methods used to assess phonological error patterns in single-word tests.

An analysis of the sonority hypothesis and cluster realization in a child with phonological disorder

This study describes the realization of onset and coda clusters in a 4-year old child acquiring American English, and with a higher than usual level of unintelligible speech. It reviews previous studies that have tested cluster realization against markedness and, in particular, the sonority hypothesis. This latter predicts steep rises in sonority at onsets and more gradual falls in sonority at codas of syllables. The data collected for this study cover four different onset cluster types and three different coda cluster types, and are derived from spontaneous speech produced during clinical sessions. An analysis of the patterns of cluster realizations shows that the participant's cluster realizations do not always follow the sonority hypothesis, and various factors are discussed that could be motivating the child's choice of realization.

Acquisition of /s/-clusters in Hebrew-speaking children with phonological disorders

This study examines the production and reduction patterns of initial /s/ clusters by Hebrew-speaking children with phonological disorders. Data were collected from 30 children with phonological disorders between the ages of 3;5-5;2. The data were elicited by means of a picture-naming task combined with a sentence completion task. Target words consisted of initial clusters, including #sC and #CC clusters. Results revealed that the percentage of correct productions of /s/+approximant clusters were significantly lower than those of the correct productions of other /s/ clusters. The differences between /s/+approximant clusters and the other /s/ clusters also emerged in the reduction patterns, where clusters from the first group were reduced to C1 but clusters from the second group were reduced to C2. There were no differences in the correct productions between the productions of SSP-violating clusters and the SSP-following clusters.

Substitution errors in the production of word-initial and word-final consonant clusters

PURPOSE

This study provides a comprehensive examination of substitutions that occur at Greenlee's 3rd stage of cluster development (M. Greenlee, 1974). At this stage of cluster acquisition, children are able to produce the correct number of consonants but with 1 or more of these consonants being substituted for another.

METHOD

Participants were 11 typically developing children ages 1;5-2;7 (years;months) who were from monolingual English-speaking homes. Consonant clusters in both word-initial and word-final position were elicited using a picture identification task.

RESULTS

Although previous studies have suggested that most cluster substitutions can be predicted from the errors children make on the corresponding singletons, our findings indicate that almost one third of substitutions in clusters are not predictable in this way. Furthermore, the majority of unpredictable substitutions produced by the children in this study resulted in clusters in which both consonants in the cluster shared the same place and/or manner of articulation. Thus, almost 70% of unpredictable substitutions appear to be motivated by assimilation within the cluster.

CONCLUSION

Ease of articulation provides the most convincing explanation for within-cluster assimilation.

Typically developing and speech-impaired children's adherence to the sonority hypothesis

During phonological development, children frequently produce consonant clusters as consonant singletons, a process commonly referred to as cluster reduction. The principles of sonority may provide a theoretical basis for explaining patterns of cluster reduction evident in children's speech. Two studies were conducted to investigate whether children's word-initial cluster reductions adhered to the sonority hypothesis. Study one involved 16 children with typically developing speech, and study two involved 40 children with impaired speech. The children's consonant cluster productions characterized by a cluster reduction were analysed. When both groups of participants reduced word-initial clusters to a target consonant, the sonority hypothesis was adhered to; but when the clusters were reduced to a non-target consonant, the sonority hypothesis was violated. Analysis of target and non-target reductions revealed that some reductions of the individual clusters, and those within specific cluster categories, adhered to the sonority hypothesis while others did not. In light of these findings, it is suggested that although sonority is a valuable concept, it may not account for all patterns of cluster reduction evident in children's speech.

Consonant cluster development in two-year-olds: general trends and individual difference

A holistic view of phonological development can be attained only through exploration of the relationship between universal developmental sequences, to establish a general pattern of development and individual learning and to provide information regarding variability. This study examined consonant cluster production, looking specifically at the relationship between general trends and individual differences as children acquire these sounds. The spontaneous speech of 16 normally developing Anglo-Australian 2-year-olds was elicited monthly for 6 months, and the corpus of 96 samples was examined using independent and relational phonological analyses. Data demonstrated that 2-year-olds were able to produce a range of consonant clusters in word-initial and word-final position, but few of the younger participants could produce consonant clusters correctly. Only half of the participants showed an increase in the percent of consonant clusters produced correctly over the 6-month period; however, their developing phonological maturity was revealed in the increase in the range and diversity of their repertoire of consonant clusters and by their closer approximations to the adult target. Specific findings of the study were compared to 10 trends for children's acquisition of consonant clusters emerging from the literature over the last 70 years.

Syllable onsets: clusters and adjuncts in acquisition

The Sonority Sequencing Principle is a presumed universal that governs the permissible sequences of consonants within syllables. In two single-subject experiments, we evaluated this principle as applied to the acquisition of onset clusters and adjuncts by children exhibiting functional phonological delays (age in years;months: 3;2 to 7;8). Experiment 1 tested the hypothesis that children abide by the Sonority Sequencing Principle in development, such that the occurrence and use of marked true clusters implies unmarked clusters, but not vice versa. This claim was validated, in part, by the gradient generalization learning patterns of children who were taught marked clusters. Others who were taught unmarked clusters exhibited limited learning characteristic of within-class generalization, with apparent gaps in sonority sequencing. Experiment 2 examined the role of adjunct sequences /sp, st, sk/, whose markedness status is questionable given their violation of the Sonority Sequencing Principle. Results indicated that children learned adjuncts consistent with patterns of within-class generalization, thereby supporting the view that these sequences are unmarked in structure. Experimental findings are integrated in discussion of the representation of onset clusters and their course of emergence in phonological acquisition relative to the Sonority Sequencing Principle.

Natural domains of cyclicity in phonological acquisition

This study expands and further validates cyclicity in the course of phonological development by exploring a potential relationship between the acquisition of singletons and clusters. The hypothesis is that children will acquire singletons followed by clusters in an alternating and recursive pattern, in complement to observed subsegmental cyclicity involving larnygeal and supralaryngeal distinctions. Six children with functional phonological disorders participated in one of three experimental conditions administered as a staggered multiple-baseline, multiple-probe design: treatment of singletons only, clusters only, or the singleton-cluster cycle. Results indicated that a singleton-cluster cycle could be induced experimentally, but it was not generally sustained by a child in expansion of the phonological repertoire. In comparison, laryngeal-supralaryngeal cyclicity was consistently maintained by all children, independent of experimental condition. A theoretical implication of these findings is that cyclicity functions as a governing principle of phonological development, but only if it is inherent to the natural domain of language. The clinical application of cyclicity in structuring treatment is considered.