Accuracy of consonant-vowel syllables in young cochlear implant recipients and hearing children in the single-word period

Toward Process-Oriented, Dimensional Approaches for Diagnosis and Treatment of Speech Sound Disorders in Children: Position Statement and Future Perspectives

BACKGROUND

Children with speech sound disorders (SSD) form a heterogeneous group, with respect to severity, etiology, proximal causes, speech error characteristics, and response to treatment. Infants develop speech and language in interaction with neurological maturation and general perceptual, motoric, and cognitive skills in a social-emotional context.

PURPOSE

After a brief introduction into psycholinguistic models of speech production and levels of causation, in this review article, we present an in-depth overview of mechanisms and processes, and the dynamics thereof, which are crucial in typical speech development. These basic mechanisms and processes are: (a) neurophysiological motor refinement, that is, the maturational articulatory mechanisms that drive babbling and the more differentiated production of larger speech patterns; (b) sensorimotor integration, which forms the steering function from phonetics to phonology; and (c) motor hierarchy and articulatory phonology describing the gestural organization of syllables, which underlie fluent speech production. These dynamics have consequences for the diagnosis and further analysis of SSD in children. We argue that current diagnostic classification systems do not do justice to the multilevel, multifactorial, and interactive character of the underlying mechanisms and processes. This is illustrated by a recent Dutch study yielding distinct performance profiles among children with SSD, which allows for a dimensional interpretation of underlying processing deficits.

CONCLUSIONS

Analyses of mainstream treatments with respect to the treatment goals and the speech mechanisms addressed show that treatment programs are quite transparent in their aims and approach and how they contribute to remediating specific deficits or mechanisms. Recent studies into clinical reasoning reveal that the clinical challenge for speech-language pathologists is how to select the most appropriate treatment at the most appropriate time for each individual child with SSD. We argue that a process-oriented approach has merits as compared to categorical diagnostics as a toolbox to aid in the interpretation of the speech profile in terms of underlying deficits and to connect these to a specific intervention approach and treatment target.

Vowel Context Effects on Consonant Repetition in Early Words

Purpose Consonant repetitions within words are a well-attested speech error pattern in children's early speech acquisition. We investigated the role of intervening vowel context in understanding speech forms containing consonant repetitions in early words. Intrasyllabic consonant-vowel (CV) sequences within consonant-vowel-consonant (CVC) and consonant-vowel-consonant-vowel (CVCV) forms containing consonant repetitions were analyzed to evaluate whether children's lack of independent movement control for the tongue in word-level sequences might contribute to these observed speech patterns. Method Spontaneous speech data produced by 10 typically developing children learning American English were analyzed longitudinally from the onset of word use to 36 months. Overall patterns and word shape effects for nine CV combinations occurring in their CVC and CVCV word shapes that contained repeated nonadjacent consonants and the intervening vowel were analyzed. Results Three CV combinations-coronal-front vowel, labial-central vowel, and dorsal-back vowel-occurred at above-chance levels. Preference for these CV patterns was strong in CVCV but not in CVC word shapes. These CV combinations occurred frequently at all time periods analyzed for CVCV's while decreasing across time for CVC's. Conclusions Analysis of intrasyllabic patterns within word forms containing consonant repetitions revealed that consonant repetitions in many early words occurred at above-chance levels in the context of articulatorily compatible vowels. Results suggest that children's production system capacities are an important contributing principle accounting for vowel context effects within word forms containing consonant repetitions during earliest speech acquisition.

Assessing consonant production in children with cochlear implants

OBJECTIVE

The objective of this study was to investigate the development of consonant inventory and accuracy in pediatric cochlear implant (CI) recipients and compare their performance to typical hearing (TH) children.

METHODS

One hundred and twenty nine children with CIs, implanted between 6-38 months of age, and 30 age-matched children with TH participated in this study. Spontaneous speech samples were collected at 3.5 and 4.5 years chronological age and the first 100 different words spoken by each participant were transcribed. Two consonant production measures were subsequently calculated to assess consonant acquisition and mastery. The percentage of Consonants Correct (CC) was used for measuring accuracy and Consonant Diversity (CD), an inventory measure, was used to identify the number of different consonants spoken by each participant. Repeated measures analyses of variance were conducted to examine the differences in consonant production scores based on presence of CI (participants with CI versus typical hearing (TH) participants), and chronological age at data collection (3.5 years versus 4.5 years).

RESULTS

CI recipients displayed lower consonant production scores compared to TH children. Children with the most device experience (32-38 months at 3.5 years) performed on par with their TH peers.

CONCLUSIONS

The two measures used in this study together appear capable of comprehensively describing the changes in consonant production skills of children. Results from this study indicate that while most CI participants display lower scores compared to TH children, many of the CI users are able to produce speech sounds on par with TH children.

Phonological processes in the speech of school-age children with hearing loss: Comparisons with children with normal hearing

PURPOSE

In this descriptive study, phonological processes were examined in the speech of children aged 5;0-7;6 (years; months) with mild to profound hearing loss using hearing aids (HAs) and cochlear implants (CIs), in comparison to their peers. A second aim was to compare phonological processes of HA and CI users.

METHOD

Children with hearing loss (CWHL, N = 25) were compared to children with normal hearing (CWNH, N = 30) with similar age, gender, linguistic, and socioeconomic backgrounds. Speech samples obtained from a list of 88 words, derived from three standardized speech tests, were analyzed using the CASALA (Computer Aided Speech and Language Analysis) program to evaluate participants' phonological systems, based on lax (a process appeared at least twice in the speech of at least two children) and strict (a process appeared at least five times in the speech of at least two children) counting criteria.

RESULTS

Developmental phonological processes were eliminated in the speech of younger and older CWNH while eleven developmental phonological processes persisted in the speech of both age groups of CWHL. CWHL showed a similar trend of age of elimination to CWNH, but at a slower rate. Children with HAs and CIs produced similar phonological processes. Final consonant deletion, weak syllable deletion, backing, and glottal replacement were present in the speech of HA users, affecting their overall speech intelligibility.

CONCLUSIONS

Developmental and non-developmental phonological processes persist in the speech of children with mild to profound hearing loss compared to their peers with typical hearing. The findings indicate that it is important for clinicians to consider phonological assessment in pre-school CWHL and the use of evidence-based speech therapy in order to reduce non-developmental and non-age-appropriate developmental processes, thereby enhancing their speech intelligibility.

Vowel production of Mandarin-speaking hearing aid users with different types of hearing loss

In contrast with previous research focusing on cochlear implants, this study examined the speech performance of hearing aid users with conductive (n = 11), mixed (n = 10), and sensorineural hearing loss (n = 7) and compared it with the speech of hearing control. Speech intelligibility was evaluated by computing the vowel space area defined by the Mandarin Chinese corner vowels /a, u, i/. The acoustic differences between the vowels were assessed using the Euclidean distance. The results revealed that both the conductive and mixed hearing loss groups exhibited a reduced vowel working space, but no significant difference was found between the sensorineural hearing loss and normal hearing groups. An analysis using the Euclidean distance further showed that the compression of vowel space area in conductive hearing loss can be attributed to the substantial lowering of the second formant of /i/. The differences in vowel production between groups are discussed in terms of the occlusion effect and the signal transmission media of various hearing devices.

Consonant Acquisition in Young Cochlear Implant Recipients and Their Typically Developing Peers

PURPOSE

Consonant acquisition was examined in 13 young cochlear implant (CI) recipients and 11 typically developing (TD) children.

METHOD

A longitudinal research design was implemented to determine the rate and nature of consonant acquisition during the first 2 years of robust hearing experience. Twenty-minute adult-child (typically a parent) interactions were video and audio recorded at 3-month intervals following implantation until 24 months of robust hearing experience was achieved. TD children were similarly recorded between 6 and 24 months of age. Consonants that were produced twice within a 50-utterance sample were considered "established" within a child's consonant inventory.

RESULTS

Although the groups showed similar trajectories, the CI group produced larger consonant inventories than the TD group at each interval except for 21 and 24 months. A majority of children with CIs also showed more rapid acquisition of consonants and more diverse consonant inventories than TD children.

CONCLUSIONS

These results suggest that early auditory deprivation does not significantly affect consonant acquisition for most CI recipients. Tracking early consonant development appears to be a useful way to assess the effectiveness of cochlear implantation in young recipients.

Production of word-initial fricatives of Mandarin Chinese in prelingually deafened children with cochlear implants

PURPOSE

This study examined the production of fricatives by prelingually deafened Mandarin-speaking children with cochlear implants (CIs).

METHOD

Fourteen cochlear implant (CI) children (2.9-8.3 years old) and 60 age-matched normal-hearing (NH) children were recorded producing a list of 13 Mandarin words with four fricatives, /f, s, ɕ, ʂ/, occurring at the syllable-initial position evoked with a picture-naming task. Two phonetically-trained native Mandarin speakers transcribed the fricative productions. Acoustic analysis was conducted to examine acoustic measures including duration, normalised amplitude, spectral peak location and four spectral moments.

RESULT

The CI children showed much lower accuracy rates and more diverse error patterns on all four fricatives than their NH peers. Among these four fricatives, both CI and NH children showed the highest rate of mispronunciation of /s/. The acoustic results showed that the speech of the CI children differed from the NH children in spectral peak location, normalised amplitude, spectral mean and spectral skewness. In addition, the fricatives produced by the CI children showed less distinctive patterns of acoustic measures relative to the NH children.

CONCLUSION

In general, these results indicate that the CI children have not established distinct categories for the Mandarin fricatives in terms of the place of articulation.

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.

Acoustic properties of vowel production in prelingually deafened Mandarin-speaking children with cochlear implants

The present study examined the acoustic features of vowel production in Mandarin-speaking children with cochlear implants (CIs). The subjects included 14 native Mandarin-speaking, prelingually deafened children with CIs (2.9-8.3 yr old) and 60 age-matched, normal-hearing (NH) children (3.1-9.0 years old). Each subject produced a list of monosyllables containing seven Mandarin vowels: [i, a, u, y, ɤ, ʅ, ɿ]. Midpoint F1 and F2 of each vowel token were extracted and normalized to eliminate the effects of different vocal tract sizes. Results showed that the CI children produced significantly longer vowels and less compact vowel categories than the NH children did. The CI children's acoustic vowel space was reduced due to a retracted production of the vowel [i]. The vowel space area showed a strong negative correlation with age at implantation (r = -0.80). The analysis of acoustic distance showed that the CI children produced corner vowels [a, u] similarly to the NH children, but other vowels (e.g., [ʅ, ɿ]) differently from the NH children, which suggests that CI children generally follow a similar developmental path of vowel acquisition as NH children. These findings highlight the importance of early implantation and have implications in clinical aural habilitation in young children with CIs.

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

It has been proposed that cochlear implant users may develop robust categorical perception skills, but that they show limited precision in perception. This article explores if a parallel contrast is observable in production, and if, despite acquiring typical linguistic representations, their early words are inconsistent. The participants were eight Spanish-learning deaf children implanted before their second birthday. Two studies examined the transition from babbling to words, and the one-word period. Study 1 found that the participants used the same sound types in babbling and in words, indicating that production is guided by stored motor patterns. No clear evidence of inconsistent production was observed. Study 2 found that in the one-word period CI users develop typical prosodic representations, but that their productions are highly unstable. Results are discussed in terms of the role of auditory feedback for the development of productive language skills.

Speech sound production in 2-year-olds who are hard of hearing

PURPOSE

The purpose of the study was to (a) compare the speech sound production abilities of 2-year-old children who are hard of hearing (HH) to children with normal hearing (NH), (b) identify sources of risk for individual children who are HH, and (c) determine whether speech sound production skills at age 2 were predictive of speech sound production skills at age 3.

METHOD

Seventy children with bilateral, mild-to-severe hearing loss who use hearing aids and 37 age- and socioeconomic status-matched children with NH participated. Children's speech sound production abilities were assessed at 2 and 3 years of age.

RESULTS

At age 2, the HH group demonstrated vowel production abilities on par with their NH peers but weaker consonant production abilities. Within the HH group, better outcomes were associated with hearing aid fittings by 6 months of age, hearing loss of less than 45 dB HL, stronger vocabulary scores, and being female. Positive relationships existed between children's speech sound production abilities at 2 and 3 years of age.

CONCLUSION

Assessment of early speech sound production abilities in combination with demographic, audiologic, and linguistic variables may be useful in identifying HH children who are at risk for delays in speech sound production.

Auditory-motor interactions in pediatric motor speech disorders: neurocomputational modeling of disordered development

BACKGROUND/PURPOSE

Differentiating the symptom complex due to phonological-level disorders, speech delay and pediatric motor speech disorders is a controversial issue in the field of pediatric speech and language pathology. The present study investigated the developmental interaction between neurological deficits in auditory and motor processes using computational modeling with the DIVA model.

METHOD

In a series of computer simulations, we investigated the effect of a motor processing deficit alone (MPD), and the effect of a motor processing deficit in combination with an auditory processing deficit (MPD+APD) on the trajectory and endpoint of speech motor development in the DIVA model.

RESULTS

Simulation results showed that a motor programming deficit predominantly leads to deterioration on the phonological level (phonemic mappings) when auditory self-monitoring is intact, and on the systemic level (systemic mapping) if auditory self-monitoring is impaired.

CONCLUSIONS

These findings suggest a close relation between quality of auditory self-monitoring and the involvement of phonological vs. motor processes in children with pediatric motor speech disorders. It is suggested that MPD+APD might be involved in typically apraxic speech output disorders and MPD in pediatric motor speech disorders that also have a phonological component. Possibilities to verify these hypotheses using empirical data collected from human subjects are discussed.

LEARNING OUTCOMES

The reader will be able to: (1) identify the difficulties in studying disordered speech motor development; (2) describe the differences in speech motor characteristics between SSD and subtype CAS; (3) describe the different types of learning that occur in the sensory-motor system during babbling and early speech acquisition; (4) identify the neural control subsystems involved in speech production; (5) describe the potential role of auditory self-monitoring in developmental speech disorders.

Emergence of speech sounds between 7 and 24 months of cochlear implant use

OBJECTIVES

To investigate the process of speech development in five 42-month-old children with profound deafness who received cochlear implants (CIs) between 19 and 36 months of age and five normal hearing (NH) age mates.

METHODS

Conversational samples were collected and transcribed. Sounds produced correctly within meaningful words (target sounds) and recognizable sounds produced in spontaneous productions (target-less sounds) were analyzed for all 10 children.

RESULTS

Revealed that there was overlap in the total number of vowels and consonants produced by the two groups. The differences between the two groups were more evident in the target condition, whereas the two groups were more similar in the target-less condition.

DISCUSSION

The similarities documented in the target-less repertoire of CI and NH children underscore the importance of examining the emerging sound system to predict the end-point sound system in children with CIs. Using target and target-less speech sound comparisons offers a supplementary view of the emergent process of speech sound development and is a valid method of analysis. Results suggest that early implantation may help some children with profound deafness develop speech sounds in a manner similar to NH age mates.

Consonant production accuracy in young cochlear implant recipients: developmental sound classes and word position effects

PURPOSE

To compare young cochlear implant (CI) recipients' consonant production accuracy with that of age- and gender-matched peers who were typically developing (TD). In addition to examining initial consonants, the authors compiled new data regarding the accuracy of final consonants and the order of consonant acquisition.

METHODS

Eleven young CI recipients with 24 months of CI experience and 11 age- and gender-matched TD peers produced target words in short sentences. Consonant production accuracy was examined for total scores, initial and final word positions, and three developmental sound classes: Early, Middle, and Late.

RESULTS

Initial consonants were produced with relatively greater accuracy than were final consonants by the TD and CI groups. Whereas initial consonants appeared to be acquired in a typical order, descriptive data suggest that this might not be the case for final consonants.

CONCLUSIONS

Although still delayed compared to age-matched peers, young CI recipients showed substantial progress in consonant acquisition. Their accuracy levels after 2 years of CI experience support the notion that implantation at a young age has added value for phonological development.

Monitoring progress in vocal development in young cochlear implant recipients: relationships between speech samples and scores from the Conditioned Assessment of Speech Production (CASP)

PURPOSE

To determine the concurrent validity of the Conditioned Assessment of Speech Production (CASP; Ertmer & Stoel-Gammon, 2008) and data obtained from speech samples recorded at the same intervals.

METHOD

Nineteen children who are deaf who received cochlear implants before their 3rd birthdays participated in the study. Speech samples and CASP scores were gathered at 6, 12, 18, and 24 months postactivation. Correlation analyses were conducted to assess the concurrent validity of CASP scores and data from samples.

RESULTS

CASP scores showed strong concurrent validity with scores from speech samples gathered across all recording sessions (6-24 months).

CONCLUSIONS

The CASP was found to be a valid, reliable, and time-efficient tool for assessing progress in vocal development during young cochlear implant recipients' first 2 years of device experience.

Coarticulation in early vocalizations by children with hearing loss: a locus perspective

Locus equations derived from productions by three children with hearing loss revealed sensory and motor influences on anticipatory coarticulation. Participants who received auditory access to speech via hearing aids and cochlear implants at different ages (5-39 months) were recorded at approximately 6 and 12 months after hearing technology fitting. One was also recorded 1 month pre-implantation. Locus equations were compared with data from typically developing children: (1) chronological age peers, and (2) peers with equivalent duration of audition, or hearing age. Anticipatory coarticulation followed typical trajectory in the child fit with hearing aids at 5 months. Anticipatory coarticulation by children with profound hearing loss using cochlear implants was closer to typically developing children with the same chronological age in syllables present pre-implantation and closer to children with equivalent hearing age in syllables emerging post-implantation. Results are discussed regarding interactions among sensory input, general motor development and specific motor experience.

Auditory-motor mapping training as an intervention to facilitate speech output in non-verbal children with autism: a proof of concept study

Although up to 25% of children with autism are non-verbal, there are very few interventions that can reliably produce significant improvements in speech output. Recently, a novel intervention called Auditory-Motor Mapping Training (AMMT) has been developed, which aims to promote speech production directly by training the association between sounds and articulatory actions using intonation and bimanual motor activities. AMMT capitalizes on the inherent musical strengths of children with autism, and offers activities that they intrinsically enjoy. It also engages and potentially stimulates a network of brain regions that may be dysfunctional in autism. Here, we report an initial efficacy study to provide 'proof of concept' for AMMT. Six non-verbal children with autism participated. Prior to treatment, the children had no intelligible words. They each received 40 individual sessions of AMMT 5 times per week, over an 8-week period. Probe assessments were conducted periodically during baseline, therapy, and follow-up sessions. After therapy, all children showed significant improvements in their ability to articulate words and phrases, with generalization to items that were not practiced during therapy sessions. Because these children had no or minimal vocal output prior to treatment, the acquisition of speech sounds and word approximations through AMMT represents a critical step in expressive language development in children with autism.