The emergence of productive speech and language in Spanish-learning paediatric cochlear implant users

Intraword Variability in Children With Auditory Brainstem Implants: A Longitudinal Comparison With Children With Cochlear Implants

PURPOSE

Intraword variability designates the phenomenon that a particular target word is produced variably by a child at one point in the child's development. In this study, the amount of intraword variability is studied longitudinally in children with auditory brainstem implants (ABIs). Auditory brainstem implantation is a relative recent technique in pediatric hearing restoration. Therefore, little is known about the phonological development of these children's speech.

METHOD

The intraword variability is investigated in three children with ABI, in comparison to children with cochlear implants, matched on lexical development. Intraword variability is measured using relative entropy in order to take into account the frequency distribution in children's productions.

RESULT

Results showed considerable variation between the three children with ABI. Still, all children had higher levels of intraword variability in their spontaneous speech productions as compared to children with cochlear implants.

CONCLUSION

It seems that children with ABI are lagging behind their phonological development in reference to children with cochlear implants.

Speech Production Accuracy and Variability in Monolingual and Bilingual Children With Cochlear Implants: A Comparison to Their Peers With Normal Hearing

Purpose This study investigates consonant and vowel accuracy and whole-word variability (also called token-to-token variability or token-to-token inconsistency) in bilingual Spanish-English and monolingual English-speaking children with cochlear implants (CIs) compared to their bilingual and monolingual peers with normal hearing (NH). Method Participants were 40 children between 4;6 and 7;11 (years;months; M _age = 6;2), n = 10 each in 4 participant groups: bilingual Spanish-English with CIs, monolingual English with CIs, bilingual Spanish-English with NH, and monolingual English with NH. Spanish and English word lists consisting of 20 words of varying length were generated, and 3 productions of each word were analyzed for percent consonants correct, percent vowels correct, and the presence of any consonant and/or vowel variability. Results Children with CIs demonstrated lower accuracy and more whole-word variability than their peers with NH. There were no differences in rates of accuracy or whole-word variability between bilingual and monolingual children matched on hearing status, and bilingual children had lower accuracy and greater whole-word variability in English than in Spanish. Conclusions High rates of whole-word variability are prevalent in the speech of children with CIs even after many years of CI experience, and bilingual language exposure does not appear to negatively impact phonological development in children with CIs. Contributions to our understanding of underlying sources of speech production variability and clinical implications are discussed.

Vocal Development in Infants and Toddlers With Bilateral Cochlear Implants and Infants With Normal Hearing

Purpose The purpose of this study was to investigate the time course of vocal development in infants and toddlers with bilateral cochlear implants (CIs; bilateral CI group) who are acquiring Finnish and to compare their progress to that of infants with normal hearing and typical development (TD group). Method Five thousand nine hundred sixty-four spontaneous utterances of 30 infants and toddlers (15 in both groups) were classified as either precanonical (PC) vocalizations, basic canonical syllables (BCS), or advanced forms (AF) levels. Time course of development and group differences were analyzed in a prospective longitudinal study during a time course of 1 year: before implantation and 1, 3, 6, 9, and 12 months after CI activation for the bilateral CI group and at 6, 9, and 12 months of age for the TD group. Results The least mature PC vocalizations decreased and the BCS and AF vocalizations increased for both the bilateral CI and TD groups during the follow-up period of 1 year. The bilateral CI group produced a lower percentage of PC vocalizations (effect size, η_p ² = .35) and a higher percentage of BCS (effect size, η_p ² = .16) and AF vocalizations (effect size, η_p ² = 0.24) than the TD group. Conclusions The findings of this study showed that vocal development of infants and toddlers with early-identified profound hearing loss is delayed before CI activation. Findings also showed that infants and toddlers with bilateral CIs make rapid advancements in vocal development after implantation compared to infants with typical development. However, their vocal development seems to remain delayed at least during the 1st year of bilateral CI use as compared to the well-documented milestones of infants and toddlers with typical development. Information about the vocal development time course following bilateral CI activation helps parents recognize progress in auditory-guided speech development before the emergence and the use of spoken words in communication.

Auditory brainstem implantation in children with hearing loss: Effect on speech production

Auditory brainstem implantation (ABI) is a recent technique in children's hearing restoration. Up till now the focus in the literature has mainly been the perceptual outcomes after implantation, whereas the effect of ABI on spoken language is still an almost unexplored area of research. This study presents a one-year follow-up of the volubility of two children with ABI. The volubility of signed and oral productions is investigated and oral productions are examined in more detail. Results show clear developmental trends in both children, indicating a beneficial effect of ABI on spoken language development.

The Effect of Word Frequency on Phonemic Accuracy in Children With Cochlear Implants and Peers With Typical Levels of Hearing

The frequency of occurrence of words and sounds has a pervasive influence on typically developing children's language acquisition. For instance, highly frequent words appear earliest in a child's lexicon, and highly frequent phonemes are produced more accurately. This study evaluates (a) whether word frequency influences word accuracy and (b) whether this is also the case for children with a history of auditory deprivation. More specifically, the influence of word frequency on phonemic accuracy is examined in deaf children with a cochlear implant (CI), and compared to age-matched children with typical hearing, between word onset and age 7. Results show that highly frequent words are produced more accurately, except for words in the highest frequency regions (i.e., predominantly closed-class words). This effect is more pronounced in children with typical hearing when compared with children with CI. Thus, children with CI are sensitive to word frequency, but to a lesser extent than peers with typical hearing.

Sensitive periods and language in cochlear implant users

This study explores the hypothesis that the existence of a short sensitive period for lower-level speech perception/articulation skills, and a long one for higher-level language skills, may partly explain the language outcomes of children with cochlear implants (CIs). The participants were fourteen children fitted with a CI before their second birthday. Data about their language skills and the environmental conditions (e.g. Family Involvement in rehabilitation) were obtained over a period of three years. Age at implantation correlated exclusively with the ratio of errors of place of articulation, a phonological feature for which CIs provide insufficient information. The degree of Family Involvement was significantly correlated with the remaining language measures. We conclude that small plasticity reductions affecting lower-level skills may partly explain the difficulties of some CI users in developing language.

Morpho-syntactic reading comprehension in children with early and late cochlear implants

This study explores morpho-syntactic reading comprehension in 19 Spanish children who received a cochlear implant (CI) before 24 months of age (early CI [e-CI]) and 19 Spanish children who received a CI after 24 months (late CI [l-CI]). They all were in primary school and were compared to a hearing control (HC) group of 19 children. Tests of perceptual reasoning, working memory, receptive vocabulary, and morpho-syntactic comprehension were used in the assessment. It was observed that while children with l-CI showed a delay, those with e-CI reached a level close to that which was obtained by their control peers in morpho-syntactic comprehension. Thus, results confirm a positive effect of early implantation on morpho-syntactic reading comprehension. Inflectional morphology and simple sentence comprehension were noted to be better in the e-CI group than in the l-CI group. The most important factor in distinguishing between the HC and l-CI groups or the e-CI and l-CI groups was verbal inflectional morphology.

What can we expect of normally-developing children implanted at a young age with respect to their auditory, linguistic and cognitive skills?

As a result of neonatal hearing screening and subsequent early cochlear implantation (CI) profoundly deaf children have access to important information to process auditory signals and master spoken language skills at a young age. Nevertheless, auditory, linguistic and cognitive outcome measures still reveal great variability in individual achievements: some children with CI(s) perform within normal limits, while others lag behind. Understanding the causes of this variation would allow clinicians to offer better prognoses to CI candidates and efficient follow-up and rehabilitation. This paper summarizes what we can expect of normally developing children with CI(s) with regard to spoken language, bilateral and binaural auditory perception, speech perception and cognitive skills. Predictive factors of performance and factors influencing variability are presented, as well as some novel data on cognitive functioning and speech perception in quiet and in noise. Subsequently, we discuss technical and non-technical issues which should be considered in the future in order to optimally guide the child with profound hearing difficulties. This article is part of a Special Issue entitled <Lasker Award>.