Sl6003 3.1 underlying deficits and diagnosis 2012


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underlying deficits in speech sound disorders

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Sl6003 3.1 underlying deficits and diagnosis 2012

  1. 1. A Model of speech processingand underlying deficits in speech sound disorders Aileen Wright SL6003 3.1 2012
  2. 2. Obligatory Reading• Differential Diagnosis of phonological disorders in Dodd (2005)
  3. 3. Learning objectives Describe the stages and routes used in processing speech in Duggierala & Dodd’s model Describe what happens if different parts of the model break down Explain the underlying deficits in each category in Dodd’s classification of speech sound disorders Explain the consequences of the underlying deficits for the child’s speech Be able to differentially diagnose the type of speech sound disorder from an analysis of speech
  4. 4. The McGurk effect• WDOwH47Y
  5. 5. Evidence: how do you account for this?• Children are taken in by the McGurk effect (Dodd & McCormack 2008)• Children can usually recognise spoken word pairs that they are unable to differentiate in production• Children can imitate nonsense words• Children can sometimes pronounce real words better in imitation than in spontaneous speech• Children’s speech errors are characterised by consistent errors that can be elegantly explained by phonological processes/realisation rules, e.g. postconsonantal sonorants delete, e.g. traintein, blue bu, new  nu, twintin• Children sometimes suppress processes in new words, but processes remain in a few very early acquired words• Children sometimes produce a word correctly, then later start using a less accurate production
  6. 6. Comparison of Stackhouse & Wells andDuggirala & Dodd models
  7. 7. Where the meaning of the word is stored: Mouse  Duggierala & Dodd’s model small rodent, long tail, eats Analyse incoming data cheese, lives in hole.. from both modalities to form phonological system Knowledge about rules ofStored entries of words phonological system, eg legal vsrecording how they sound: illegal consonant combinationsMouse  /maʊs/. Containenough information for a heardword to be recognized asdistinct from other similar-sounding words (e.g. TAP vs Realisation rules:CAP; CAP vs CAT). A set of mental processes that govern the construction of aPragmatic knowledge, rules of phonological plansocial interaction Stored plans for high frequencyMental processes that derive artic. utterancesInstructions from abstract plan.Includes phonetic specification of Abstract plan. Drivesphonemes. Assembles the gestural phonetic program thattargets (articulatory instructions) into sets up motor specscorrect sequence in real time, takinginto account the context, e.g. peripheral production of speech at the levelassimilations and the appropriate of the vocal tract. Gestures required forintonation for a question form. accurate pronunciation are produced in form of overt muscular action
  8. 8. Justification of model (Dodd & McCormack 1995) McGurk effect Evidence: errors are consistent Across the board change happens when a processSocio-linguistic variation in is suppressed speech eg “gay speech” Phonological therapy generalises to untreated targetsMunson, B. & Babel, M. 2007. LooseLips and Silver Tongues, or, ProjectingSexual Orientation Through SpeechLanguage and Linguistics Compass 1/5:416–449,
  9. 9. Processing routes Input from both McGurk effect modalities Input of linguistic knowledge Repetition of non- (constraints) towords/unknown words realisation rules Ready made phonological plans for known words
  10. 10. Levels of breakdown on the model (Dodd & McCormack 1995) Visually impaired children make more errors of place of CPD children showed no artic, rather then manner, preference for legal over unlike non VI illegal words: Performed worse on PA tasks than other gps. lack of knowledge of rules of phon. system?IC children performed worse in receptive and expressive vocab than Control, PD and CPD: impaired ability to access full forms of words? IC children made more IC gp worse than other 3 on phonological than phonetic errors: non-verbal motor (tracing) phonological planning deficit rather and verbal motor (learning than phonetic programming non words) tasks Delayed gp showed no specific deficit. Just slightly behind controls on all tasks
  11. 11. Why Speech disorders? Perceptual deficits • Deficits in auditory processing • Tallal & Piercy 1973, 1974,1975 YES • Children with SLI/dyslexia have difficulties with fast temporal processing of tones • Coady, Kuender, Evans 2005 • No difficulty if normal speech used rather than NO synthetic sound • children distinguish minimal pairs they do not produce11/09/09 3.1 Speech sound disorders 11 11
  12. 12. Why speech disorders?: Cognitive-linguistic impairment: • Children with inconsistent disorder are poorer in expressive vocab. tests: • Difficulty word-finding, accessing phonological Lexical deficits? shape of word? • Impaired ability to access full specifications of words  inconsistent word production • Difficulty abstracting knowledge from mental lexicon about nature of phonological system • E.g. knowledge of phonological legality: Children with consistent disorder show no preference for Impaired rule legal over illegal nonsense names derivation ability? • Suggests deficit in deducing constraints inherent in native phonological system • E.g. phonological awareness: Children with consistent disorder show difficulty with recognising rhyme and alliteration 11/09/09 3.1 Speech sound disorders 12 12
  13. 13. Why speech disorders? Output processing • Motor accuracy test: tracing • Inconsistent group performed worse Impaired than other gps ability to • Nonsense word learning generate • Inconsistent group performed worse phonological than other gps plans • Suggests inconsistent group have motor planning problem not specific to speech11/09/09 3.1 Speech sound disorders 13 13
  14. 14. Why speech disorders? Motor execution • mental processes that derive precise Impaired articulatory instructions for the ability to pronunciation of a word from an generate abstract phonological plan phonetic • Inconsistent gp: more phonological plans? than phonetic errors, therefore no evidence for this Motor • Anatomical anomaly, muscle execution disfunction impairment • Degree?11/09/09 3.1 Speech sound disorders 14 14
  15. 15. Consistent phonological disorder Underlying deficit: rule abstraction/pattern recognition Determining the statistical patterns in theLearning which contrasts ambient language so theyare relevant in the can efficiently segmentambient language continuous speech into word-sized units
  16. 16. Inconsistent speech disorderHolm, Crosbie & Dodd (2007) Differentiating Normal Variability from Inconsistency in Childrens Speech: Normative DataInternational Journal of Language & Communication Disorders, v42 n4 p467-486 Underlying deficit: phonological planning i.e. generating a plan that Incomplete phonological plan specifies the sequences of leads to inadequate phonetic programmes with articulatory consonants and vowels to parameters that are too broad. be produced. • neural messages that sequence • Underspecified or degraded speech movements provide phonological plans. May be due imprecise instructions. to: • having inaccurate phonological representations, • problems accessing accurate phonological representations • difficulty setting up the phonological plan.11/09/09 3.1 Speech sound disorders 16 16
  17. 17. Conclusions: underlying deficitArticulation Delayed: Consistent Inconsistent Disorder disordered: disordered: Motor cognitive- Difficulties with no specific execution linguistic phonological impairment deficit planning deficit: impaired Degraded ability to phonological derive and representations, or difficulty organise accessing them knowledge about nature of ambient phonological Motor planning difficulty system11/09/09 3.1 Speech sound disorders 17 17
  18. 18. ConclusionsSkills are inter-related: impairment of one will effect othersDiffering impairment profiles indicates areas of generalimpairment that guide further Ax and interventionSurface speech error patterns can be described in different ways,but description has limited explanatory powerFor profound understanding of speech disorders: • Different profiles require different patterns of impairment • More generic mental abilities may underlie some kinds of speech disorder11/09/09 3.1 Speech sound disorders 18 18
  19. 19. Diagnosis & the Speech Processing Model Articulation: • difficulties in phonetic programming or motor execution Phonological Delay: • no apparent specific deficits in speech processing chain. Little behind control on all tasks. Consistent Disordered: • often have phonological awareness difficulties, indicates a linguistic impairment in deriving knowledge about their language system Inconsistent: • difficulties with phonological planning11/09/09 3.1 Speech sound disorders 19 19
  20. 20. Differential Diagnosis:Articulation disorder Three types • Organic ( dysarthria) • Structural anomaly( cleft palate) • Functional articulation disorder Inability to produce a sound in isolation, or in any phonetic context. Same production in spontaneous production as on imitation • Child cannot produce the sound. • Differential diagnosis requires a stimulability probe OR sound is distorted (not another phoneme) e.g. lateralised /s/, nasal fricative for /s/ • In this case, child may be stimulable for correct sound, but has habituated the wrong sound26/09/11 3.1 Speech Sound Disorder - classification 20 20
  21. 21. Differential Diagnosis:Phonological delay The child’s phonological error patterns are those which occur during normal development, but at least some are typical of younger children • Chronologically mismatched pattern of errors • 6mths+ delay is significant • Changing system or frozen system- monitor for 3mths or home programme • Child may catch up by themselves • 5 years+: frozen system: not likely to change without intervention, so needs therapy26/09/11 3.1 Speech Sound Disorder - classification 21 21
  22. 22. Differential Diagnosis:Consistent Phonological Disorder Use of non-developmental error patterns (atypical, disordered, unusual, idiosyncratic) • Variety of syllable structures and stress patterns is restricted • May have developmental patterns also • Only one non- developmental error means disorder • Often have phonological awareness difficulties26/09/11 3.1 Speech Sound Disorder - classification 22 22
  23. 23. Differential Diagnosis:Inconsistent Phonological Disorder At least 40% variability e.g. when asked to name 25 pictures on 3 occasions • Produce same word in multiple error forms • Not correct/incorrect: maturing system • Lack of stability in phonological system • Indicates a pervasive speech disorder • Difficulties in phonological planning26/09/11 3.1 Speech Sound Disorder - classification 23 23
  24. 24. Differential diagnosis: (Dodd et al 2002)Inconsistent phonological disordervs.developmental verbal dyspraxia (DVD) • Inconsistent phonological disorder is frequently mis-diagnoses as DVD • Differences: Developmental Verbal Dyspraxia Inconsistent Phonological Disorder Difficulties producing many sounds in Are able to produce most sounds in isolation isolation Frequent difficulties with oro-motor Have age appropriate oro-motor skills skills Imitation worse than spontaneous imitation better than spontaneous production productions More variable productions in different High degree of inconsistent productions contexts of the same lexical item in the same context- 40% 26/09/11 3.1 Speech Sound Disorder - classification 24 24
  25. 25. Characterisation of a SSD• Josh (4:11) presents with an inconsistent phonological disorder and some developmental processes. Inconsistency is 56% and PCC on the DEAP is 44%. Where he uses them, he is fronting velars and / and he is gliding /r/  /w/. /, Other than this his phoneme inventory is age appropriate. He uses 1, 2 and some three syllable words. He produces /l/ blends but no other clusters. Intelligibility is severely reduced for all listeners.• Mary (3:6) presents with a phonological delay characterised by final consonant deletion of all consonants except nasals and stopping of all fricatives and affricates. She is also using the age-appropriate processes of weak syllable deletion, cluster reduction and gliding of /r//w/. PCC on the DEAP is 62%. Intelligibility is severely reduced for all listeners.• Paddy (3:11) presents with a consistent phonological disorder characterised by a very limited inventory of consonants (p, b, m ….) and structures (CV, VC, VCV), Word initially all fricatives are produced as /h/. PCC on the DEAP is 57%. Intelligibility is severely reduced for all listeners.• Aoife (4:11) presents with a mild phonological delay characterised by cluster reduction of all /s/ clusters. She also has an articulation difficulty with //. Otherwise her inventory of phonemes and structures is age appropriate. PCC on the DEAP is 86%. The delay is resulting in reduced intelligibility for unfamiliar listeners.