Tuesday, December 13, 2011

Speech Development Patterns and Phonological Awareness in Preschool Children

Mann, V.A., and Foy, J.G. (2007). Speech development patterns and phonological awareness in preschool children. Annals of Dyslexia, 57, 51-74.

Researchers hypothesized that children who failed to master production of the early 8 consonants had phonological awareness deficits. Findings: children who made no consonant errors had advanced phonological awareness relative to other children in the study. Both production speech and speech errors, however, were linked with rhyme awareness. This association may help identify preschool children at risk for reading problems.

Link between phonological awareness and speech perception - differences between good and poor readers may lie in the ability to produce phonological representations. Influence of speech perception on reading moderated by phonological awareness. Variance in phoneme identification accounts for significant variance in phoneme deletion (Chiappe et al, 2001). Deficits in speech perception play a causal role in the deficient phonological procession of poor readers and the inability to distinguish phonemes is the link between speech perception and deficient phonological awareness. Some attribute it to short term memory processes (Brady et al, 1989; Mann et al., 1980) others say it is the mental lexicon (Elbro, 96; Fowler & Swainson, 2004). Unclear whether two different impairments or a single common denominator.
Study examines processes involving the mental lexicon: word production vocabulary, naming speed, and judgments about rhymes. Also examines digit span, nonsense word repetition and PA in pseudowords, placing demands on short term memory.

Study focuses on speech production in relation to development of PA. Are speech production problems evident among children who read poorly or those at risk based on family history. Are children with speech & hearing problems prone to reading problems?

Studies populations of delayed, normal, and advanced PA according to articulatory    development and also study ways in which their PA skills relate to patterns of misarticulations. Children w/ sp & hearing problems generally have more reading problems (Menyuk et al., 91; Aram & Hall, 89; Bishop & Adams, 1990)

Delayed talkers are disproportionately often poor readers, have weak phonological awareness, and weak speech perception, though not all develop reading problems.(Paul & Jennings, Ratner, 1994; Scarboough & Dobrich, 1990; Whitehurst et al., 1991, Carroll et al., 2003).

Study would determine the set of consonants that children articulate and describe misarticulations. Many normal misarticulations of preschoolers resolve by school age or earlier in a predictable way. Most correctly produce /m/ but not a well developed /s/. produce variants of the /s/ that isn't phonemically salient in target language, (dentalized or lateralized productions.) Don't usually change the consonant to another (stopping). A delay in outgrowing normal productive errors may reflect phonological problems leading to poor PA and rdg difficulties.

Phonological process errors in disorder studies are referred to as deletion of final consonants, syullable reduction, palatal fronting, velar fronting, consonant harmony, stopping of fricative, and afficates, cluster simplification and liquid simplification.

85% of preschoolers (age 4) in Iowa-Nebraska Articulation Norms Project could pronounce p, b, k, g, t, d, w, m, n, h, j in initial and final positions. Kids with articulation problems less able to produce  r, l, f, v, s, z, Ɵ, ð ( voiceless and voiced /th/) (/sh/ voiceless as in ship), Ʒ (/zh/ as in exposure), t (/ch/ as in chip), dƷ (ĵ /j/ as in edge or jump)  Normal development involves acquisition of all major phoneme classes by age 3 except for liquids /l/ and /r/, which are more likely to be spoken by age 5, except for sibilants [s] [z] [ʃ] [tʃ] [dʒ] [ʒ] usually acquired by age 7 (without lisps) (Porter and Hodson, 2001). Their analysis identified 3 types of consonant errors atypical among preschoolers: omissions of single consonants, omission of one consonant within a cluster, and substitutions that changed the articulation place or manner: /t/ for /s/, /d/ for /l/, /d/ for /g/  Dit me some dum.

A particular class of consonants misarticulated past a given age give rise to the most abnormalities. Those who didn't catch up in one study (Roberts et al, 1998) misarticulated ethe early acquired phonemes: /p, b, t, d, k, g, w, j/. They were prone to consonant deletion, gliding and stopping. Shriberg 1993 had similar results. Identified a sequence for acquisition of consonantal phonemes based on clustering. The early 8 were /p, b, j, n, w, d, m, h/ the middle 8 were /t, ng, k, g, f, v, ch, j/ and late were /sh, th Voiced & unvoiced, s, z, l, r, zh/. The only distinguishing characteristic between children whos speech didn't normalize and those whose speech did was a nonisignificant trend for the non-normalized group to show lower performance on the early 8 phonemes. Shriberg found 8 sound-change categories that describe over 90% of deleetiona and substitution errors (over age 3) Final consonant deletion, xluster simplification, unstressed syllable deletion and substitution (liquid simplification, palatal fronting, velar fronting & assimilation consonant harmony)  Studies of children who had early and persistent deficits in speech production indicate a trend towards select impairment on early developing phonemes during the preK years. Patters of errors suggest no trend toward delayed children using more of some processes and less of others but do indicate what errors are typical and atypical.

This study questions whether children's errors relate to their level of phonological awareness and bear any relation to other phonological skills like speech perception or working short-term memory. Reading is typically delayed for these children.

Noted the co-occurrence of articulatory problems with early developing sounds and deficient awareness. Weakness in representation may lead them to be less able to judge or manipulate phonological units like rhyming or PA tasks. Advanced children exhibit mature control over consonant articulation and may possess strong ability to represent phonological structure and PA.

Hesketh (2000) studied 3.5-5 yr olds with deficits in articulation (no therapy) and normal scores on language, vocab, nonverbal IQ and hearing. Speech disordered group had lower PA scores on 5 tasks rhyme matching, word-initial matching, blending phonemes, word-initial segmentation and matching, consonant deletion).  Statistically sig differences in subtests wre onset matchng and word-initial segmentation and matching. Older kids with production errors also deficient in letter name knowledge and PA compared to children who were developing normally. Preschool chikdren with history of speech sound disorders shown to have deficient p\PA and LK (Raitano et al., 2004) Rvachew and Grawburg 2006, showed childen with speech sound disorders ahd lower PA skills than normal kids and vocabulary and speech perception skills successfully predicted PA development.

Bertelson, et al., 1998; Hulme, 2002; Hulme et al., 2002; Morais et al., 1986) suggest PA and rhyme awareness skills are separate processes that make differential contributions to reading achievement. Foy & Mann (2001, 2003) accord with such evidence in suggesting that the awareness of rhyme more closely aligned with Ph perception and production abilities where awareness of phonemes relates to literacy and educational exposure.

Hypotheses: speech production linked with measures of early literacy skills
Patterns of consonant errors will predict speech perception, vocabulary, naming and digit span, and their relation to reading and PA as they relate to the representation of phonological structure. In particular, atypical errors may associate with weaker PA and reading and language skills.

Participants 102 kids, 7 preschools or daycares in S. CA, Caucasian, AA, Hisp, Asian, mixed race. Ages 4-6 low to upper middle class, spoke English as primary lang. 13 children at familial risk for reading problems compared to 13 others matched on age, sex bilingual status, vocabulary, and no significant differences on measures.

Subsample of 70 reexamined 3 months later. Report PA and rhyme awareness measures at time 2. All normal development.

Tests: Vocabulary, digit span (working memory), letter knowledge & Phoneme Awareness (pre-literacy skills), rhyme awareness, naming speed, nonword repetition, speech discrimination

Results for hypothesis 1: Speech production will be linked with measures of early literacy skills

Early 8 speech sounds - errors significantly correlated with vocabulary, digit span, letter knowledge, rhyme awareness, naming speed, and speech discrimination
Middle 8 speech sounds - in addition to same early 8 variable correlation, phoneme awareness and nonword repetition significant.
Late 8 speech sounds - vocabulary, digit span, letter knowledge, rhyme awareness, naming speech, nonword repletion, speech discrimination. Children

Delayed group - (n = 25)  familial risk children - 38% made errors on the early 8 sounds compared to 17% not at familial risk.
Typical group - n=65 no errors in early 8 but errors on late 8, and some on middle 8.  46% of children at familial risk in this group; 72% not at familial risk.
Advanced group (n=12) - no deficits on early, middle, or late 8 sounds. Ten had no errors on Goldman Fristoe Test, 15% at familial risk for reading problems in this group compared to 10% not at familial risk.

Children in delayed group had significantly lower scores on expressive vocabulary, verbal short term memory, letter knowledge, rhyme awareness, letter knowledge, speech discrimination, slower naming responses, than children in typical group.
 Children in advanced group significantly higher scores than typical children for rhyme awareness, nonword repetition accuracy, vocabulary, verbal short term memory, rhyming, letter knowledge, speech discrimination, and faster naming responses.

Hypothesis 2 Consonantal errors are related to reading related measures

Most common developmental processes: stridency deletion, stopping, liquid simplification, cluster simplification, palatal fronting, consonant harmony. 
Normal processes that occurred infrequently were initial voicing, final devoicing, velar fronting, deletion of final consonant, syllable reduction.

Special condition of this study: included children advanced in articulation skills who made no errors on their consonant inventory. Their phonological skills were significantly advanced in rhyme awareness compared to peers with articulatory deficits. Superior rhyme awareness appeared to be a characteristic of children with early control of phonemes that are typically not mastered early (the late 8 group).  Evidence from multiple studies suggest that advqanced early speech perception skills predict language development (Kuhl, 2004, 2005).

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