Chapter 19 Hearing Impairment and Developmental Disabilities

1. Chapter 19Hearing Impairment and Developmental Disabilities Kiyoshi Otomo

2. Introduction • The speech acquisition of children with hearing impairment and various developmental disability can follow trajectories that are delayed or unique • Understanding the sensory, motor, and cognitive factors helps SLPs to facilitate the phonological development in these children. • This chapter focuses on • Hearing impairment • Down syndrome • Autism • Fragile X syndrome

3. Hearing Impairment Children rely on auditory input from the speech of others, as well as from their own speech, to acquire the phonological system of their language Children with hearing impairment rely on the acoustic information from their residual hearing and the output from their amplification devices They may rely more on visual and kinesthetic information than children with typical hearing do.

4. Early Speech Development in Children with Hearing Impairments Deaf and hearing children produce a range of pre-speech vocalizations (growls, raspberries, squeals) Pre-speech vocalizations of one deaf infant became less frequent over the first 30 weeks (Maskarinec, 1981) One deaf infant produced no repetitive canonical babble from 8 to 13 months (Oller, 1985) In other cases, canonical babble in deaf infants was substantially delayed (Eilers & Oller, 1994; Oller & Eilers, 1988) Smaller consonant inventory among hearing impaired infants 4 – 28 months (Stoel-Gammon & Otomo, 1986) The number of consonant types failed to increase among hearing impaired infants months (Stoel-Gammon & Otomo, 1986) The proportion of labial consonants increased substantially and stayed at high levels until age 3 in hearing-impaired infants, whereas this proportion decreased in infants with typical hearing sensitivity (Stoel-Gammon, 1988) Infants with hearing impairment showed reduced F2 ranges, consistent with reduced tongue movement during vowels -> lowered speech intelligibility (McGowan, 2008)

5. Meaningful Speech in Children with Hearing Hmpairment • The speech of children with profound hearing impairment is difficult to understand • Prosody • Consonants, vowels, although labial consonants are more accurate than other consonants • Voicing errors • Syllable deletion, epenthesis • Vowel substitutions, frequently using a central vowel (/ə/ or /ʌ/

6. Speech of Children with Otitis Media with Effusion (OME) • Elevated hearing thresholds in early childhood can predict speech problems later on • 33% of children who had experienced an average hearing loss greater than 20 dB at 12–18 months of age exhibited some kind of speech disorder, whether clinical or subclinical, at 3 years of age, compared to only 2% of children with less than 20 dB hearing loss at 12-18 months (Shriberg et al., 2000) • Findings about associations between OME and speech problems are unclear, but early hearing loss does predict speech problems

7. Speech Perception in Individuals with Hearing Impairment 19S1 The Rainbow Passage read by a woman who wears hearing aids 19S2 The Stella Passage read by a woman who wears hearing aids 19S3 Personal story told by a woman who wears hearing aids In adults with hearing loss, consonant confusion matrices show that the most common type of misperception is place of articulation Children who are fitted with hearing aids achieve good word recognition in quiet but not in noise Children may benefit from visual and tactile information as they listen to a speaker

8. Cochlear Implants Figure 19.1 The components of a cochlear implant device

9. Young infants with profound congenital or prelingual hearing loss can be implanted with cochlear implants • The perceived sound is different from acoustically perceived sound - temporal and spectral resolution is not as fine-grained • Nonetheless, the benefit from cochlear implants is clear • Six children who received implants before age 3 years rapidly developed intelligible speech (although not to the same level as children without hearing impairment) (Flipsen et al., 2006) • Other studies show that consonant accuracy improves as well and that labials become less frequent • Vowel accuracy improved, as verified with F2 measurements • Prosody improved for phrasing and pitch, but not for resonance and placement of stress

10. Residual speech errors • Some vowels and/or consonants may be missing from the inventory • Phonological processes can include cluster reduction, stopping, liquid simplification, final consonant deletion, unstressed syllable deletion, velar fronting • Children seem to reach a ceiling with their speech improvements • Effects of age at implant • In a study of children implanted at ages 10 – 36 months (Ertmer et al., 2007), the children implanted at younger ages developed the highest level of vocalizations (dipthongs, jargon, complex syllables) at younger ages than children who were implanted at older ages. • In a study of three implant age groups (2-5 years), 5-8 years, 8-13 years) (Tomblin et al., 2005), the children in the youngest implant group improved their speech production at the most rapid pace • Factors that are thought to influence speech development in cochlear implant users: • Neural plasticity • Amount of daily use of the device • Technology of the device • Degree of educational emphasis on aural-oral communication

11. 19S4 The Rainbow Passage read by a woman who wears cochlear implants 19S5 The Stella Passage read by a woman who wears cochlear implants 19S6 Personal story told by a woman who wears cochlear implants

12. Down Syndrome One of the best-researched chromosomal disorders Occurs ~ 1:800 births Caused by an extra copy of chr 21, either the whole chromosome or a part of it, hence the other term for it, trisomy 21 Children with Down syndrome have some distinct morphological features, e.g., short stature and slanted eyelids Down syndrome causes various degrees of intellectual disability, which affects speech development The speech of children with Down syndrome is described as difficult to understand One study used the Children’s Speech Intelligibility Measure (Wilcox & Morris, 1999) and showed that ~ half the words were unintelligible (Cleland et al., 2010)

13. Prelinguistic Development of Children with Down Syndrome • Early studies showed that the pre-speech productions of infants with Down syndrome is similar to that of typically developing children in terms of numbers of vowel and consonant utterances and the variety of vowels and consonants (Dodd, 1972; Smith & Oller, 1981) • Newer studies showed some differences (Lynch et al., 1995): • Infants with Down syndrome had a lower ratio of # canonical babble syllables/# all syllables • Infants with Down syndrome started canonical babble ~ 2 months later than typically developing children • Canonical babble was less consistent in infants with Down syndrome • Those infants who began canonical babble earlier in life had greater social communication skills later

14. Meaningful Speech of Children with Down Syndrome • Children with Down syndrome can acquire all phonemes of their language (Stoel-Gammon, 1980; Van Borsel) • There is great individual variability (Kumin et al., 1994) • Age of acquisition of /p, s/ ranged from 1 to 8 years • Speech errors in children and adolescents with Down syndrome are similar to those in younger children with typical development • Final consonant deletion, cluster reduction, devoicing, stopping, gliding, palatal and velar fronting, and syllable deletion • More accurate in word-initial position compared to final • Children with Down syndrome were found to be delayed • 1 to 2 years by age 3 • 4 years by age 6, 7 • Newer studies have shown that children and adolescents with Down syndrome have idiosyncratic speech errors (Cleland et al., 2010, Rupela & Manjula, 2007 ) • Initial consonant deletion • Other deviant processes (occurring infrequently) • Simpler word shapes

15. Inconsistency of Production in Children with Down Syndrome • Children with Down syndrome produced more inconsistent speech errors compared to typically developing children matched for mental age and children with other types of intellectual disability • Children with Down syndrome were more accurate in imitation than in productions without a model (Dodd & Thompson, 2001) • Hypotheses • Motor planning • Phonological representation of target word

16. Hearing in Children with Down Syndrome • Many children with Down syndrome have hearing impairments • OME due to craniofacial structural differences and immune system deficiencies • Sensorineural hearing impairments also can occur, due to smaller inner ear structures • When children with Down syndrome and hearing impairment are fitted with hearing aids, there is some evidence that their speech intelligibility improves (Hans et al., 2010) • The clinical utility of cochlear implants in these cases is still under investigation but in children where the intellectual impairment is mild, improvement has been noted (Lee, 2010)

17. Oral Structures in Children with Down Syndrome • Weak facial muscles • Overall low muscle tone • Open-mouth stance • Slight tongue protrusion • Narrow, short, flat palates • This results in restricted movement space for the tongue – height and volume of the oral cavity are smaller • Vowel quality affected • Consonantal point of contact less precise

18. Motor Skills in Children with Down Syndrome General clumsiness in gross and fine motor tasks (Frith & Frith, 1974) Greater difficulty using tongue, jaw, and lips for feeding than unaffected twins during first three years of life (Spender et al., 1995) Control of lips, tongue, velopharynx, and larynx for speech movements less developed (Barnes et al., 2006) Some researchers claim that the motor clumsiness in children with Down syndrome is similar to the motor programming/sequencing deficit in childhood apraxia of speech (CAS) (Kumin & Adams, 2000)

19. Verbal Short-Term Memory and Phonological Awareness in Children with Down Syndrome Individuals with Down syndrome have impairments in verbal short-term memory, e.g., imitating a sequence of numbers (Jarrod et al., 2001) Individuals with Down syndrome also show deficits in phonological processing (e.g., segmenting words, identifying rhymes) Treatment targeting phonological processing did not improve overall speech accuracy in children with Down syndrome (Kennedy & Flynn, 2003)

20. Phonological Representation • Two features of theoretical interest • More accurate imitated vs. spontaneous productions: reduced cognitive load when retrieving the phonological form? • Inconsistent errors in repeated productions: apraxia? • Both: phonological underspecification? • Which, in turn, could be associated with hearing impairment? • More research is needed to tease out the effects of cognitive impairment vs. hearing impairment

21. 19S7 Six utterances produced by a 3-year-old boy with Down syndrome Spontaneous utterance (“Balloon. A ballon.”) Elicited utterance (“Baseketball.”) Elicited utterance (“A duck.”) Imitated utterance (“Skates.”) Elicited utterance (“Elephant.”) Imitated utterance (“Piggy”)

22. Autism Spectrum Disorder (ASD)* *For updated terminology, please see DSM-V • Three areas of characteristic traits: • impaired social interactions • deficits in communication skills • restricted repetitive and stereotyped patterns of behaviors, interests, and activities • Additional subtypes • High-functioning autism • Asperger syndrome • Notes: • These two terms are sometimes used interchangeably • The DSM-V proposes to eliminate the term Asperger syndrome • Communication abilities range from completely nonverbal to typical vocabulary and syntax • Pragmatic use of language is often affected

23. Speech Characteristics of Children with ASD • Prosodic abilities are a relative weakness (pitch, intonation, intensity) • Phonological abilities are a relative strength • Echolalia with perfect segments • In some children with ASD who have intellectual disability, speech errors have been noted • Idiosyncratic speech errors • Phonological processes that are also observed in typically developing children • A substantial proportion of children with ASD including high-functioning autism and Asperger syndrome show speech errors that are residual distortions (e.g., dentalizedsibiliants, derhotacization; Shriberg et al., 2001) • The number of errors in a given child with ASD may be low, but the percentage of children who have any speech errors is high (41% of 69 children; Cleland et al., 2010) • Hypothesis: Deficit in social cognition • Children may not notice their errors • Children may not be motivated to change their speech patterns

24. Auditory Processing in Children with ASD • Individuals with ASD show differences in speech perception • Infants showed reduced preference for child-directed speech and this was correlated with receptive language ability later (Paul et al., 2007) • Individuals with ASD had difficulty identifying stress patterns in given linguistic contexts (Paul et al., 2005) • Children with high-functioning ASD did not show evidence of ERP activity for vowel changes but did show ERP activity for simple and complex tones (Ceponiene et al., 2003) • Individuals with ASD show differences in responses to speech sounds that may be associated with structural differences in the auditory system at various levels including brainstem, cerebellum, and auditory cortex (Nieto Del Rincón, 2008)

25. Motor skills in children with ASD Do children with ASD have neuromotor difficulties? Study results have produced conflicting evidence. Some studies have reported that children with autism were significantly less skillful than typically developing children in tasks involving fine and gross motor functioning of the hands and body, but significant differences in oral-motor functions were not observed between the groups (Noterdaeme, Mildenberger, Minow, & Amorosa, 2002). Other studies have documented motor difficulties in hand and orofacial systems (Amato & Slavin, 1998) More research is needed to observe complex associations among ASD traits and speech errors.

26. Fragile X Syndrome Second only to Down syndrome as cause of intellectual disability of genetic or chromosomal origin Loss of the fragile X mental retardation 1 protein (FMRP). This genetic disorder is linked to the X chromosome Prevalence 1 in 4,000 for males and 1 in 8,000 for females Males have moderate to severe intellectual disability whereas females have a mild form In males, the intellectual disability is similar to that in Down syndrome but the social use of language similar to ASD

27. Intelligibility and Fluency of Speech in Children with Fragile X Syndrome Generally less intelligible than typically developing children Speech rate can be rapid and impulsive Speech showed evidence of cluttering, with rapid and fluctuating rate of speech and repetitions of sounds, words, and phrases (Hanson et al., 1986) These impression may also be influenced by the use of shorter utterances and fewer pauses (Zajac, 2006)

28. Phonological Inaccuracies in the Speech of Children with Fragile X Syndrome In boys with Fragile X syndrome, phonological errors were less frequent than boys with Down syndrome matched for intellectual ability (Roberts at al., 2005) Boys with Fragile X syndrome were delayed in their phonological development, compared to typically developing boys Caveat: there is considerable individual variation in the population of boys with Fragile X syndrome

29. Possible Factors Affecting the Speech of Children with Fragile X Syndrome Boys with Fragile X syndrome experienced otitis media during the first five years of life more frequently than their unaffected siblings and children with other types of intellectual disability Difficulty repeating non-reduplicated multisyllabic sequences, such as “pa-ta-ka” (Paul, et al., 1984) Reduced performance on speech function tasks involving the lips, tongue, and velopharynx and in those involving coordinated speech movements (E. F. Barnes, et al., 2006). More research is needed how these factors influence speech development in Fragile X syndrome

30. Connections Chapter 20 describes the importance of hearing screens in a speech assessment Chapter 7 describes the prosodic deficits in children with ASD

31. Concluding Remarks • The effect of hearing impairment on speech development is straightforward • Intellectual disabilities have more complex relationships with speech development • Memory • Motor • Cognition • Social interaction • Speech can also be influenced by very low birth weight • Understanding each parameter can help to manage the speech deficits in the most effective way possible • Management can involve • treating the speech deficits • Compensatory strategies such as hearing aids, cochlear implants, and AAC devices