Neurological and developmental foundations of ... - iVent Services

sk→k, skw→k, t, kw, gw; spl→p, b, pl, pw;spr→p, pw, pr, sp; str→t, d, st, tw, sw;skr→k, w, kw, gw, fw (Smit, 1993b)PHONOLOGICAL PROCESSESPresentCluster reduction, fronting of velars, fronting/S/, stopping /v, T, D, tS, dZ/, gliding,context sensitive voicing (Grunwell, 1987)Most prevalent = cluster reduction & liquiddeviations (gliding) (Preisser et al., 1988)2;0 = final consonant deletion, liquidsimplification, later stopping, clusterreduction, vowelisation3;0 = later stopping, cluster simplification(Watson & Scukanec, 1997b)2;7-3;0 = 23% fronting(Lowe, Knutson & Monson, 1985)DecliningFinal consonant deletion (Grunwell, 1987)Affrication, depalatisation, gliding,meathesis, prevocalic voicing, , vowelchanges (James, 2001)SYLLABLE STRUCTURESyllable shapesCV, CVC, CVCV, CVCVC(Stoel-Gammon, 1987)CV, VC, CVC, 2-syllable (Shriberg, 1993)Monosyllabic words - V, CV, VC, CVC,CCVC, CVCC, CCVCC,CCVCCC, CCCCVCPolysyllabic words - V, CV, VC, CVC, CCVC(Dodd, 1995; Watson & Skucanec, 1997)PROSODYnumbers of stress errors in target words withirregular stress.” (Kehoe, 2001, p. 284)METALINGUISTIC SKILLS1;6-2;0 = monitor own utterances: repairspontaneously, adjust speech to differentlisteners, practice sounds, words, sentences(Clark, adapted by Owens, 1996, p. 386)LANGUAGEMLU2;0 = 2.1 (range 1.2-3.2)2;3 = 2.4 (range 1.7-3.8)2;6 = 2.8 (range 2.1-3.6)2;9 = 3.5 (range 2.1-5.2)3;0 = 3.8 (range 3.3-4.7)(Watson & Scukanec, 1997b)Brown’s Stage II (2;3 – 2;6)MLU = 2.0 – 2.5Modulation of meaning. Emergence ofgrammatical morphemes (e.g. plurals)Brown’s Stage III (2;7 – 2;10)MLU = 2.5 – 3.0Development of sentence form. Nounphrase elaboration and auxiliarydevelopment (questions and negatives)(Brown, adapted by McLaughlin, 1998)PREDICTORSmember of a consonant cluster (oneelement realisation), then preserve themembers but one may be produced ina non-adult manner (two elementrealisation), and finally they willproduce the consonant clustercorrectly (correct realisation). Otherdevelopmental sequences arepossible, particularly for word-finalconsonant clusters.9. There is an interrelationship betweencluster reduction, cluster simplificationand correct productions of consonantclusters. Initially, most children reduceconsonant clusters. Over time, theoccurrence of cluster reductiondiminishes, while the occurrence ofcluster simplification increases.Simultaneously, the occurrence ofcorrect productions increases, untileventual mastery of production.10. Despite there being a typicaldevelopmental sequence, theacquisition of consonant clusters ismarked by reversals and revisions withconsiderable individual variation.Warning signs of impairment at 2 years:Numerous vowel errors, frequent deletion ofinitial consonants, frequent use of glottalstop or [h] for a variety of consonants,backing (eg: [ku] for “two”), and, finalconsonant deletion particularly as the childapproaches 3 years. (Stoel-Gammon, 1987)Trends of typical consonant clusterdevelopment (McLeod et al., 2001a)1. Two-year-old children can produceconsonant clusters, but these clustersmay not be of the same form as theambient language.Predictors of late talkers’ phonological2. Word-final consonant clustersgenerally appear in inventories earlierskills at 2;9: smaller phonetic inventories,than word-initial clusters.less diverse and complex syllable structures,3. Two-element consonant clusters arelower PCC scores, sound variability, atypical“Significantly greater number of stressgenerally produced and masterederror patterns, little change in developmenterrors in SWS words (S = strong; W =earlier than three-element clusters.weak). Tendency for greater number ofacross time (Williams & Elbert, 2003, p. 150)4. Consonant clusters containing stopsstress errors in SWSW words. Stress errors(e.g., /pl/, /kw/) are acquired generallywere more frequent in imitated thanbefore consonant clusters containing3 years “Children with SLI and LD showed aspontaneous productions.” (Kehoe, 1997).fricatives (e.g., /st/, /Tr/).delay in the acquisition of segments, syllabic“An analysis of children’s truncation error5. Young children typically delete onestructures and word structures, and in thesyllable deletion patterns revealed theelement of a consonant cluster (clusterfollowing robust findings:simplification processes, compared with theirreduction).(a) Stressed and word-final unstressedage control group. However, SLI children6. Homonymy occurs in young children’ssyllables are preserved more frequently thanalso displayed significant differences vis-avistheir language level controls, mainly inattempts to produce consonantnonfinal unstressed syllables,clusters. Homonymy frequently occurs(b) word-internal unstressed syllables withas a result of cluster reduction;early acquisitions: vowels, nasals and stopsobstruent onsets are preserved morehowever, homonyms can also occur asat the segmental level, and in CV structuresfrequently than word-internal syllables witha result of cluster creation.sonorant onsets,at the syllabic level. There is also a7. There are a number of other non-adult(c) unstressed syllables with non-reducedsimplification process that seems to be morerealisations of consonant clusters; thevowels are preserved more frequently thanprevalent in these children than in theirmost common is cluster simplification,unstressed syllables with reduced vowels,with others including epenthesis andlanguage level controls, namely, the deletion(d) right-sided stressed syllables arecoalescence. Metathesis is rare.of unstressed syllables, mainly initial ones.”preserved more frequently than left-sided8. The acquisition of consonant clusters(Aguilar-Mediavilla, Sanz-Torrent, & Serrastressedsyllables.is gradual and there is a typicalAn analysis of children’s stress patternsRaventos, 2002, p. 573)developmental sequence. It is not anrevealed that children made greaterall-or-nothing process. For word-initialclusters, children may initially delete aMcLeod & Bleile – ASHA 2003 (smcleod@csu.edu.au) Page 6