Categorical perception of speech by children with specific language impairments

Phoneme Categorization in Prelingually Deaf Adult Cochlear Implant Users

PURPOSE

Phoneme categorization (PC) for voice onset time and second formant transition was studied in adult cochlear implant (CI) users with early-onset deafness and hearing controls.

METHOD

Identification and discrimination tasks were administered to 30 participants implanted before 4 years of age, 21 participants implanted after 7 years of age, and 21 hearing individuals.

RESULTS

Distinctive identification and discrimination functions confirmed PC within all groups. Compared to hearing participants, the CI groups generally displayed longer/higher category boundaries, shallower identification function slopes, reduced identification consistency, and reduced discrimination performance. A principal component analysis revealed that identification consistency, discrimination accuracy, and identification function slope, but not boundary location, loaded on a single factor, reflecting general PC performance. Earlier implantation was associated with better PC performance within the early CI group, but not the late CI group. Within the early CI group, earlier implantation age but not PC performance was associated with better speech recognition. Conversely, within the late CI group, better PC performance but not earlier implantation age was associated with better speech recognition.

CONCLUSIONS

Results suggest that implantation timing within the sensitive period before 4 years of age partly determines the level of PC performance. They also suggest that early implantation may promote development of higher level processes that can compensate for relatively poor PC performance, as can occur in challenging listening conditions.

Neural patterns elicited by lexical processing in adolescents with specific language impairment: support for the procedural deficit hypothesis?

Background

Deficits in procedural memory have been proposed to account for the language deficits in specific language impairment (SLI). A key aspect of the procedural deficit hypothesis (PDH) account of SLI is that declarative memory is intact and functions as a compensatory mechanism in the acquisition of language in individuals with SLI. The current study examined the neural correlates of lexical-phonological and lexical-semantic processing with respect to these predictions in a group of adolescents with SLI with procedural memory impairment and a group of chronologically age-matched (CA) normal controls.

Methods

Participants completed tasks designed to measure procedural and declarative memory and two ERP tasks designed to assess lexical-semantic and lexical-phonological processing in the auditory modality. Procedural memory was assessed using a statistical learning task. Lexical-semantic processing was assessed using a sentence judgment task modulating semantic congruency and lexical-phonological processing was assessed using a word/nonword decision task modulating word frequency. Behavioral performance on the tasks, mean amplitude of the cortical response, and animated topographs were examined.

Results

Performance on the statistical word-learning task was at chance for the adolescents with SLI, whereas declarative memory was no different from the CA controls. Behavioral accuracy on the lexical-semantic task was the same for the adolescents with SLI and CA controls but accuracy on the lexical-phonological task was significantly poorer for the adolescents with SLI as compared to the CA controls. An N400 component was elicited in response to semantic congruency on the lexical-semantic task for both groups but differences were noted in both the location and time course of the cortical response for the SLI and CA groups. An N400 component was elicited by word frequency on the lexical-phonological task for the CA controls not for the adolescents with SLI. In contrast, post hoc analysis revealed a cortical response based on imageability for the adolescents with SLI, but not CA controls. Statistical word learning was significantly correlated with speed of processing on the lexical decision task for the CA controls but not for the adolescents with SLI. In contrast, statistical word learning ability was not correlated with the modulation of the N400 on either task for either group.

Conclusion

The behavioral data suggests intact semantic conceptual knowledge, but impaired lexical phonological processing for the adolescents with SLI, consistent with the PDH. The pattern of cortical activation in response to semantic congruency and word frequency suggests, however, that the processing of lexical-semantic and lexical-phonological information by adolescents with a history of SLI may be supported by both overlapping and nonoverlapping neural generators to those of CA controls, and a greater reliance on declarative memory strategies. Taken together, the findings from this study suggest that the underlying representations of words in the lexicons of adolescents with a history of SLI may differ qualitatively from those of their typical peers, but these differences may only be evident when behavioral data and neural cortical patterns of activation are examined together.

Who is Right? A Word-Identification-in-Noise Test for Young Children Using Minimal Pair Distracters

PURPOSE

Many children have difficulties understanding speech. At present, there are few assessments that test for subtle impairments in speech perception with normative data from U.K. children. We present a new test that evaluates children's ability to identify target words in background noise by choosing between minimal pair alternatives that differ by a single articulatory phonetic feature. This task (a) is tailored to testing young children, but also readily applicable to adults; (b) has minimal memory demands; (c) adapts to the child's ability; and (d) does not require reading or verbal output.

METHOD

We tested 155 children and young adults aged from 5 to 25 years on this new test of single word perception.

RESULTS

Speech-in-noise abilities in this particular task develop rapidly through childhood until they reach maturity at around 9 years of age.

CONCLUSIONS

We make this test freely available and provide associated normative data. We hope that it will be useful to researchers and clinicians in the assessment of speech perception abilities in children who are hard of hearing or have developmental language disorder, dyslexia, or auditory processing disorder.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.17155934.

Adult perception of stop consonant voicing in American-English-learning toddlers: Voice onset time and secondary cues

Most studies of speech perception employ highly controlled stimuli. It is not always clear how such results extend to the processing of natural speech. In a series of experiments, we progressively explored the role of voice onset time (VOT) and potential secondary cues in adult labeling of stressed syllable-initial /b d p t/ produced by typically developing two-year-old learners of American English. Taken together, the results show the following: (a) Adult listeners show phoneme boundaries in labeling functions comparable to what have been established for adult speech. (b) Adult listeners can be sensitive to distributional properties of the stimulus set, even in a study that employs highly varied naturalistic productions from multiple speakers. (c) Secondary cues are available in the speech of two-year-olds, and these may influence listener judgments. Cues may differ across places of articulation and the VOT continuum. These results can lend insight into how clinicians judge child speech during assessment and also have implications for our understanding of the role of primary and secondary acoustic cues in adult perception of child speech.

Relaciones entre habilidades de percepción y producción de habla y el desarrollo morfosintáctico en niños con Trastorno Fonológico que hablan español

La investigación sobre el desarrollo gramatical y su posible relación con los déficits de procesamiento de habla en niños con Trastorno Fonológico (TF) es escasa, especialmente para la lengua española. El objetivo es analizar la influencia de las habilidades de percepción y producción de habla en el desarrollo morfosintáctico de los niños con TF sin Trastorno del Lenguaje (TL). Participaron 52 niños de habla española de 4 a 6 años: 26 con TF y 26 con desarrollo típico (DT) emparejados en edad cronológica, cociente de inteligencia no verbal y nivel de vocabulario receptivo. El desarrollo morfosintáctico se evaluó con el test de lenguaje CELF-Preschool-2-Spanish. Los niños realizaron una tarea de percepción de habla en concreto de discriminación y reconocimiento fonológico y la producción se analizó mediante un análisis fonológico a partir de una tarea de denominación de imágenes. Los niños con TF obtuvieron puntuaciones significativamente más pobres que los niños con DT en todas las variables. Un análisis de mediación mostró un efecto positivo entre la percepción del habla y el desarrollo gramatical con la mediación de la producción del habla. Los niños con TF presentan peor desarrollo morfosintáctico que los niños con DT. Parecen aprender el lenguaje de forma diferente porque son menos eficaces extrayendo, manipulando y produciendo las características del habla. En ellos, el desarrollo gramatical parece depender de varios factores incluyendo la percepción y producción de habla y del efecto sinérgico que estos dos procesos tienen el uno sobre el otro.

Altered brain structures in the dorsal and ventral language pathways in individuals with and without developmental language disorder (DLD)

Developmental Language Disorder (DLD) is a neurodevelopmental disorder characterized by difficulty learning and using language, and this difficulty cannot be attributed to other developmental conditions. The aim of the current study was to examine structural differences in dorsal and ventral language pathways between adolescents and young adults with and without DLD (age range: 14-27 years) using anatomical magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). Results showed age-related structural brain differences in both dorsal and ventral pathways in individuals with DLD. These findings provide evidence for neuroanatomical correlates of persistent language deficits in adolescents/young adults with DLD, and further suggest that this brain-language relationship in DLD is better characterized by taking account the dynamic course of the disorder along development.

Assessing Fine-Grained Speech Discrimination in Young Children With Bilateral Cochlear Implants

HYPOTHESIS

Children of 2 to 3 years old with cochlear implants can perform consonant discriminations using fine-grained acoustic cues.

BACKGROUND

Children born with severe-to-profound deafness are provided with early cochlear implantation (<2 yr) to maximize oral communication outcomes. Little is known regarding their abilities to discriminate consonant contrasts for accurately identifying speech sounds.

METHODS

Using a Reaching for Sound paradigm to collect behavioral responses, consonant contrast discrimination was measured in 13 children with bilateral cochlear implants (BiCIs; aged 28-37 mo), and 13 age-matched normal-hearing (NH) children. Four contrast pairs were tested: 1) place + voicing, 2) place, 3) voicing, and 4) reduced voice-onset-time cue. Using standard processing strategies, electrodograms showing pulsatile stimulation patterns were created retrospectively to assess the spectral-temporal cues delivered through the clinical speech processors.

RESULTS

As a group, children with BiCIs were able to discriminate all consonant contrasts at a level that was above chance, but their performance was poorer than NH children. Larger individual variability in discrimination performance was found in children with BiCIs. Stepwise regression revealed that, in the place contrast, chronological age was correlated with improved discrimination performance among children with BiCIs.

CONCLUSION

Children with BiCIs were able to discriminate consonant contrasts using fine-grained spectral-temporal cues above chance level but more poorly than their NH peers. Electrodogram analysis confirmed the access to spectral-temporal cues in the consonant contrasts through clinical speech processors. However, the cue saliency might not have be enough for children with BiCIs to achieve the same discrimination accuracy as NH children.

Individual Differences in Distributional Learning for Speech: What's Ideal for Ideal Observers?

Purpose Speech perception is facilitated by listeners' ability to dynamically modify the mapping to speech sounds given systematic variation in speech input. For example, the degree to which listeners show categorical perception of speech input changes as a function of distributional variability in the input, with perception becoming less categorical as the input, becomes more variable. Here, we test the hypothesis that higher level receptive language ability is linked to the ability to adapt to low-level distributional cues in speech input. Method Listeners (n = 58) completed a distributional learning task consisting of 2 blocks of phonetic categorization for words beginning with /g/ and /k/. In 1 block, the distributions of voice onset time values specifying /g/ and /k/ had narrow variances (i.e., minimal variability). In the other block, the distributions of voice onset times specifying /g/ and /k/ had wider variances (i.e., increased variability). In addition, all listeners completed an assessment battery for receptive language, nonverbal intelligence, and reading fluency. Results As predicted by an ideal observer computational framework, the participants in aggregate showed identification responses that were more categorical for consistent compared to inconsistent input, indicative of distributional learning. However, the magnitude of learning across participants showed wide individual variability, which was predicted by receptive language ability but not by nonverbal intelligence or by reading fluency. Conclusion The results suggest that individual differences in distributional learning for speech are linked, at least in part, to receptive language ability, reflecting a decreased ability among those with weaker receptive language to capitalize on consistent input distributions.

Sleep Promotes Phonological Learning in Children Across Language and Autism Spectra

Purpose Establishing stable and flexible phonological representations is a key component of language development and one which is thought to vary across children with neurodevelopmental disorders affecting language acquisition. Sleep is understood to support the learning and generalization of new phonological mappings in adults, but this remains to be examined in children. This study therefore explored the time course of phonological learning in childhood and how it varies by structural language and autism symptomatology. Method Seventy-seven 7- to 13-year-old children, 30 with high autism symptomatology, were included in the study; structural language ability varied across the sample. Children learned new phonological mappings based on synthesized speech tokens in the morning; performance was then charted via repetition (without feedback) over 24 hr and followed up 4 weeks later. On the night following learning, children's sleep was monitored with polysomnography. Results A period of sleep but not wake was associated with improvement on the phonological learning task in childhood. Sleep was associated with improved performance for both trained items and novel items. Structural language ability predicted overall task performance, though language ability did not predict degree of change from one session to the next. By contrast, autism symptomatology did not explain task performance. With respect to sleep architecture, rapid eye movement features were associated with greater phonological generalization. Conclusions Children's sleep was associated with improvement in performance on both trained and novel items. Phonological generalization was associated with brain activity during rapid eye movement sleep. This study furthers our understanding of individual differences in the acquisition of new phonological mappings and the role of sleep in this process over childhood. Supplemental Material https://doi.org/10.23641/asha.11126732.

Contextual Influences on Phonetic Categorization in School-Aged Children

Perceptual stability in adult listeners is supported by the ability to process acoustic-phonetic variation categorically and dynamically adjust category boundaries given systematic contextual influences. The current study examined the developmental trajectory of such flexibility. Adults and school-aged children (5-10 years of age) made voicing identification decisions to voice-onset-time (VOT) continua that differed in speaking rate and place of articulation. The results showed that both populations were sensitive to contextual influences; the voicing boundary was located at a longer VOT for the slow compared to the fast speaking rate continuum and for the velar compared to the labial continuum, and the magnitude of the displacement was slighter greater for the adults compared to the children. Moreover, the two populations differed in terms of the absolute location of the voicing boundaries and the categorization slopes, with slopes becoming more categorical as age increased. These results demonstrate that sensitivity to contextual influences on speech perception emerges early in development, but mature perceptual tuning requires extended experience.

Cognitive Predictors of Spoken Word Recognition in Children With and Without Developmental Language Disorders

PURPOSE

This study examined the influence of cognitive factors on spoken word recognition in children with developmental language disorder (DLD) and typically developing (TD) children.

METHOD

Participants included 234 children (aged 7;0-11;11 years;months), 117 with DLD and 117 TD children, propensity matched for age, gender, socioeconomic status, and maternal education. Children completed a series of standardized assessment measures, a forward gating task, a rapid automatic naming task, and a series of tasks designed to examine cognitive factors hypothesized to influence spoken word recognition including phonological working memory, updating, attention shifting, and interference inhibition.

RESULTS

Spoken word recognition for both initial and final accept gate points did not differ for children with DLD and TD controls after controlling target word knowledge in both groups. The 2 groups also did not differ on measures of updating, attention switching, and interference inhibition. Despite the lack of difference on these measures, for children with DLD, attention shifting and interference inhibition were significant predictors of spoken word recognition, whereas updating and receptive vocabulary were significant predictors of speed of spoken word recognition for the children in the TD group.

CONCLUSION

Contrary to expectations, after controlling for target word knowledge, spoken word recognition did not differ for children with DLD and TD controls; however, the cognitive processing factors that influenced children's ability to recognize the target word in a stream of speech differed qualitatively for children with and without DLDs.

Speech Perception Deficits in Mandarin-Speaking School-Aged Children with Poor Reading Comprehension

Previous studies have shown that children learning alphabetic writing systems who have language impairment or dyslexia exhibit speech perception deficits. However, whether such deficits exist in children learning logographic writing systems who have poor reading comprehension remains uncertain. To further explore this issue, the present study examined speech perception deficits in Mandarin-speaking children with poor reading comprehension. Two self-designed tasks, consonant categorical perception task and lexical tone discrimination task were used to compare speech perception performance in children (n = 31, age range = 7;4-10;2) with poor reading comprehension and an age-matched typically developing group (n = 31, age range = 7;7-9;10). Results showed that the children with poor reading comprehension were less accurate in consonant and lexical tone discrimination tasks and perceived speech contrasts less categorically than the matched group. The correlations between speech perception skills (i.e., consonant and lexical tone discrimination sensitivities and slope of consonant identification curve) and individuals' oral language and reading comprehension were stronger than the correlations between speech perception ability and word recognition ability. In conclusion, the results revealed that Mandarin-speaking children with poor reading comprehension exhibit less-categorized speech perception, suggesting that imprecise speech perception, especially lexical tone perception, is essential to account for reading learning difficulties in Mandarin-speaking children.

Evaluating the sources and functions of gradiency in phoneme categorization: An individual differences approach

During spoken language comprehension listeners transform continuous acoustic cues into categories (e.g., /b/ and /p/). While long-standing research suggests that phonetic categories are activated in a gradient way, there are also clear individual differences in that more gradient categorization has been linked to various communication impairments such as dyslexia and specific language impairments (Joanisse, Manis, Keating, & Seidenberg, 2000; López-Zamora, Luque, Álvarez, & Cobos, 2012; Serniclaes, Van Heghe, Mousty, Carré, & Sprenger-Charolles, 2004; Werker & Tees, 1987). Crucially, most studies have used 2-alternative forced choice (2AFC) tasks to measure the sharpness of between-category boundaries. Here we propose an alternative paradigm that allows us to measure categorization gradiency in a more direct way. Furthermore, we follow an individual differences approach to (a) link this measure of gradiency to multiple cue integration, (b) explore its relationship to a set of other cognitive processes, and (c) evaluate its role in individuals' ability to perceive speech in noise. Our results provide validation for this new method of assessing phoneme categorization gradiency and offer preliminary insights into how different aspects of speech perception may be linked to each other and to more general cognitive processes. (PsycINFO Database Record

Phonological processing in children with specific language impairment with and without reading difficulties

BACKGROUND

Specific language impairment (SLI) is heterogeneous and identifying subgroups within it may help explain the aetiology of the condition. Phonological processing abilities distinguish between children with SLI who do and do not have reading decoding impairments (RDIs).

AIMS

To probe different levels of phonological processing in children with SLI with and without RDI to investigate the cognitive basis of these differences.

METHODS & PROCEDURES

A total of 64 children aged 5-17 years were classified using the results of standardized language and single-word reading tests into those with no SLI and no RDI (No SLI/No RDI) (N = 18), no SLI but with RDI (No SLI/RDI) (N = 4, not included in analyses because of the small number), SLI/No RDI (N = 20), and SLI/RDI (N = 22). The groups were compared on a range of tasks engaging different levels of phonological processing (input and output processing and phonological awareness).

OUTCOMES & RESULTS

The SLI/RDI group was distinguished from the SLI/No RDI and No SLI/No RDI groups by more errors in the longer items in non-word repetition and by poorer phonological awareness. Non-word discrimination scores indicated a gradient of performance across groups that was not associated with a qualitatively different pattern of performance.

CONCLUSIONS & IMPLICATIONS

This is the first study contrasting input and output processes associated with phonological processing. The results suggest that deficits in SLI plus RDI may be associated with impairment in actively maintaining phonological representations for phonological processing, which is not present in those without RDI and which leads to reading decoding difficulties.

A Closer Look at Phonology as a Predictor of Spoken Sentence Processing and Word Reading

The goal of this study was to tease apart the roles of phonological awareness (pA) and phonological short-term memory (pSTM) in sentence comprehension, sentence production, and word reading. Children 6- to 10-years of age (N = 377) completed standardized tests of pA ('Elision') and pSTM ('Nonword Repetition') from the Comprehensive Test of Phonological Processing. Concepts and Following Directions (CFD) and Formulated Sentences (FS) were taken from the Clinical Evaluation of Language Fundamentals-Fourth Edition, as measures of sentence comprehension and production, respectively. Children also completed the Word Identification (Word Id) and Word Attack (Word Att) subtests of the Woodcock Reading Mastery Test-Third Edition. Hierarchical multiple regression analyses controlling for age and nonverbal IQ revealed that Elision was the only significant predictor of CFD and FS. While Elision was the strongest predictor of Word Id and Word Att, Nonword Repetition accounted for additional variance in both reading measures. These results emphasize the usefulness of breaking down phonological processing into multiple components and they also have implications language and reading disordered populations.

Phonetic categorisation and cue weighting in adolescents with Specific Language Impairment (SLI)

This study investigates phonetic categorisation and cue weighting in adolescents and young adults with Specific Language Impairment (SLI). We manipulated two acoustic cues, vowel duration and F1 offset frequency, that signal word-final stop consonant voicing ([t] and [d]) in English. Ten individuals with SLI (14.0-21.4 years), 10 age-matched controls (CA; 14.6-21.9 years) and 10 non-matched adult controls (23.3-36.0 years) labelled synthetic CVC non-words in an identification task. The results showed that the adolescents and young adults with SLI were less consistent than controls in the identification of the good category representatives. The group with SLI also assigned less weight to vowel duration than the adult controls. However, no direct relationship between phonetic categorisation, cue weighting and language skills was found. These findings indicate that some individuals with SLI have speech perception deficits but they are not necessarily associated with oral language skills.

Individual differences in language ability are related to variation in word recognition, not speech perception: evidence from eye movements

PURPOSE

The authors examined speech perception deficits associated with individual differences in language ability, contrasting auditory, phonological, or lexical accounts by asking whether lexical competition is differentially sensitive to fine-grained acoustic variation.

METHOD

Adolescents with a range of language abilities (N = 74, including 35 impaired) participated in an experiment based on McMurray, Tanenhaus, and Aslin (2002). Participants heard tokens from six 9-step voice onset time (VOT) continua spanning 2 words (beach/peach, beak/peak, etc.) while viewing a screen containing pictures of those words and 2 unrelated objects. Participants selected the referent while eye movements to each picture were monitored as a measure of lexical activation. Fixations were examined as a function of both VOT and language ability.

RESULTS

Eye movements were sensitive to within-category VOT differences: As VOT approached the boundary, listeners made more fixations to the competing word. This did not interact with language ability, suggesting that language impairment is not associated with differential auditory sensitivity or phonetic categorization. Listeners with poorer language skills showed heightened competitors fixations overall, suggesting a deficit in lexical processes.

CONCLUSION

Language impairment may be better characterized by a deficit in lexical competition (inability to suppress competing words), rather than differences in phonological categorization or auditory abilities.

Speech perception and lexical effects in specific language impairment

Using an identification task, we examined lexical effects on the perception of vowel duration as a cue to final consonant voicing in 12 children with specific language impairment (SLI) and 13 age-matched (6;6-9;6) peers with typical language development (TLD). Naturally recorded CV/t/sets [word-word (WW), nonword-nonword (NN), word-nonword (WN) and nonword-word (NW)] were edited to create four 12-step continua. Both groups used duration as an identification cue but it was a weaker cue for children with SLI. For NN, WN and NW continua, children with SLI demonstrated certainty at shorter vowel durations than their TLD peers. Except for the WN continuum, children with SLI demonstrated category boundaries at shorter vowel durations. Both groups exhibited lexical effects, but they were stronger in the SLI group. Performance on the WW continuum indicated adequate perception of fine-grained duration differences. Strong lexical effects indicated reliance on familiar words in speech perception.

Phonological and lexical effects in verbal recall by children with specific language impairments

BACKGROUND & AIMS

The present study examined how phonological and lexical knowledge influences memory in children with specific language impairments (SLI). Previous work showed recall advantages for typical adults and children due to word frequency and phonotactic pattern frequency and a recall disadvantage due to phonological similarity among words. While children with SLI have well-documented memory difficulties, it is not clear whether these language knowledge factors also influence recall in this population.

METHODS & PROCEDURES

Sixteen children with SLI (mean age = 10;2) and chronological age-matched typically developing children (CAM) controls recalled lists of words differing in phonological similarity, word frequency and phonotactic pattern frequency. While previous studies used a small set of words appearing in multiple word lists, the current study used a larger set of words, without replacement, so that children could not gain practice with individual test items.

OUTCOMES & RESULTS

All main effects were significant. Interactions revealed that children with SLI were affected by similarity, but less so than their peers, comparably affected by word frequency and unaffected by phonotactic pattern frequency.

CONCLUSIONS & IMPLICATIONS

Results due to phonological similarity suggest that children with SLI use less efficient encoding, while results due to word frequency and phonotactic pattern frequency were mixed. Children with SLI used coarse-grained language knowledge (word frequency) comparably with peers, but were less able to use fine-grained knowledge (phonotactic pattern frequency). Paired with phonological similarity results, this suggests that children with SLI have difficulty establishing robust phonological knowledge for use in language tasks.

Assessing speech perception in children with language difficulties: effects of background noise and phonetic contrast

Deficits in speech perception are reported for some children with language impairments. This deficit is more marked when listening against background noise. This study investigated the speech perception skills of young children with and without language difficulties. A speech discrimination task, using non-word minimal pairs in an XAB paradigm, was presented to 20 5-7-year-old children with language difficulties and 33 typically-developing (TD) children aged between 4- to 7-years. Stimuli were presented in quiet and in background noise (babble), and stimuli varied in phonetic contrasts, differing in either place of articulation or presence/absence of voicing. Children with language difficulties performed less well than TD children in all conditions. There was an interaction between group and noise condition, such that children with language difficulties were more affected by the presence of noise. Both groups of children made more errors with one voicing contrast /s z/ and there was some indication that children with language difficulties had proportionately greater difficulty with this contrast. Speech discrimination scores were significantly correlated with language scores for children with language difficulties. Issues in developing material for assessment of speech discrimination in children with LI are discussed.

Evidence of deficient central speech processing in children with specific language impairment: the T-complex

OBJECTIVE

This paper examined neurophysiological correlates of speech in children with language impairment (LI) and typical language development (TLD) across four experiments using different speech stimuli and tasks.

METHODS

The T-complex event-related potential (ERP) components and other ERP components (e.g., mismatch negativity [MMN]; N400) were examined. A subset of the children participated in more than one of the experiments.

RESULTS

73% of the children with LI had poor T-complex measures compared to only 13% of children with TLD. The T-complex measures were more comparable, in terms of indicating typical versus deviant processing, to neurophysiological measures of language processing, such as lexical discrimination, than to other measures of auditory and speech processing, such as the MMN. Only one LI child showed no poor measures and 64% showed three or more poor neurophysiological measures. However, 50% of children with TLD showed no poor neurophysiological measures, and 82% of the TLD children showed no more than two poor measures.

CONCLUSIONS

These results suggest that poor auditory processing, as measured by the T-complex, is a marker for LI and that multiple deficits serve to mark LI.

SIGNIFICANCE

The T-complex measures, indexing secondary auditory cortex, reflect an important aspect of processing in speech and language development.

P300 as a measure of processing capacity in auditory and visual domains in specific language impairment

This study examined the electrophysiological correlates of auditory and visual working memory in children with Specific Language Impairments (SLI). Children with SLI and age-matched controls (11;9-14;10) completed visual and auditory working memory tasks while event-related potentials (ERPs) were recorded. In the auditory condition, children with SLI performed similarly to controls when the memory load was kept low (1-back memory load). As expected, when demands for auditory working memory were higher, children with SLI showed decreases in accuracy and attenuated P3b responses. However, children with SLI also evinced difficulties in the visual working memory tasks. In both the low (1-back) and high (2-back) memory load conditions, P3b amplitude was significantly lower for the SLI as compared to CA groups. These data suggest a domain-general working memory deficit in SLI that is manifested across auditory and visual modalities.

Maturation of speech discrimination in 4- to 7-yr-old children as indexed by event-related potential mismatch responses

OBJECTIVES

This study examined maturation of mismatch responses (MMRs) to an English vowel contrast (/I/ versus /ε/) in 4- to 7-yr-old children.

DESIGN

Event-related potentials were recorded to a standard [ε] and deviant [I] vowel presented in trains of 10 stimuli at a rate of 1/650 msecs and with an intertrain interval of 1.5 secs. Each train contained two deviant vowels. Averaged responses were calculated for the infrequent (deviant) and the frequent (standard) trials for each child and compared across age groups.

RESULTS

Significantly greater negativity, consistent with the adult mismatch negativity (MMN), was observed to the deviants between 300 and 400 msecs for both younger (4- and 5-yr-old) and older (6- and 7-yr-old) children. This MMN-like negativity shifted earlier in latency by 25 msecs/yr with increasing age. Most of the children younger than 5.5 yrs and some of the older children also showed a positive MMR (p-MMR) peaking between 100 and 300 msecs. The p-MMR diminished in amplitude with increasing age.

CONCLUSIONS

Maturation of speech discrimination, as indexed by MMN, occurs more rapidly between 4 and 7 yrs of age for vowels than for tones. A p-MMR preceding the MMN also reflects discrimination in younger children and declines in amplitude with age.

The role of phonotactic frequency in sentence repetition by children with specific language impairment

PURPOSE

Recent work suggests that specific language impairment (SLI) results from a primary deficit in phonological processing. This deficit is most striking in nonword repetition tasks, where semantic and syntactic demands are eliminated. Children with SLI repeat nonwords less accurately than do their unimpaired peers, which may reflect difficulty extracting phonological regularities from their lexicons. However, recent evidence suggests that having children with SLI respond to meaningless syllables such as nonwords underestimates their language abilities. Therefore, phonological processing was measured by having children repeat meaningful sentences containing target words differing in phonotactic pattern frequency (PPF).

METHOD

Eighteen children with SLI (mean age=9;0 [years;months]) and 18 age-matched controls repeated acoustically degraded sentences containing CVC target words differing in PPF, occurring in either subject position or sentence-final position.

RESULTS

Accuracy results revealed significant main effects due to group, PPF, and sentence position (sentence final>subject). Further, the nonsignificant Group×PPF interaction suggests that both groups of children were similarly affected by PPF.

CONCLUSION

Children with SLI repeated CVC target words less accurately overall but showed similar sensitivity to PPF as typical controls, suggesting that PPF affects repetition of real words embedded in sentential contexts by both children with SLI and typically developing peers.

Role of phonotactic frequency in nonword repetition by children with specific language impairments

BACKGROUND

Children with specific language impairments (SLI) repeat nonwords less accurately than typically developing children, suggesting a phonological deficit. Much work has attempted to explain these results in terms of a phonological memory deficit. However, subsequent work revealed that these results might be explained better as a deficit in phonological sensitivity.

AIMS

This study used a nonword repetition task to examine how children with SLI extract phonological regularities from their language input.

METHODS & PROCEDURES

Eighteen English-speaking children with SLI (7;3-10;6) and 18 age-matched controls participated in two English nonword repetition tasks. Three- and four-syllable nonwords varied in a single phonotactic frequency manipulation, either consonant frequency or phoneme co-occurrence frequency, while all other factors were held constant. Repetitions were scored in terms of accuracy as either the percentage of phonemes correctly produced or phoneme co-occurrences (diphones) correctly produced. In addition, onset-to-onset reaction times and repetition durations were measured.

OUTCOMES & RESULTS

Accuracy results revealed significant group, length, and phonotactic frequency effects. Children with SLI repeated nonwords less accurately than age-matched peers, and all children repeated three-syllable nonwords and those with higher frequency phonotactic patterns more accurately. However, phonotactic frequency by group interactions were not significant. Timing results were mixed, with group reaction time differences for co-occurrence frequency, but not consonant frequency, and no group repetition duration differences.

CONCLUSIONS & IMPLICATIONS

While children with SLI were less accurate overall, non-significant interactions indicate that both groups of children were comparably affected by differences in consonant and diphone frequency.

Electrophysiological indices of discrimination of long-duration, phonetically similar vowels in children with typical and atypical language development

PURPOSE

The authors investigated the neurophysiological bases of vowel perception in children with specific language impairment (SLI) compared with typical language development (TLD) controls using 250-ms phonetically similar vowels. In a previous study, children with SLI showed a poor neurophysiological response (the mismatch negativity [MMN]) to 50-ms versions of these vowels, regardless of whether attention was directed to (attend) or away (passive) from the auditory modality (V. Shafer, M. Morr, H. Datta, D. Kurtzberg, & R. Schwartz, 2005). They hypothesized that longer vowels would allow for improved speech perception.

METHOD

Brain responses were elicited to the vowel contrast in 2 conditions: (a) attend and (b) passive. Behavioral discrimination and identification responses were also examined.

RESULTS

Both SLI and TLD groups showed evidence of discrimination (MMN) of the vowels in the attend and passive conditions. Only subtle differences in the scalp topography of a late negative (LN) brain component were observed between groups. The SLI compared with the TLD group showed significantly poorer identification of these long vowels, as found previously with the shorter vowels.

CONCLUSIONS

Increased vowel duration can improve discrimination in children with SLI. However, poor identification of these longer vowels by some children with SLI suggests a deficit in long-term phonological representations or accessing these representations.

Individual differences in online spoken word recognition: Implications for SLI

Thirty years of research has uncovered the broad principles that characterize spoken word processing across listeners. However, there have been few systematic investigations of individual differences. Such an investigation could help refine models of word recognition by indicating which processing parameters are likely to vary, and could also have important implications for work on language impairment. The present study begins to fill this gap by relating individual differences in overall language ability to variation in online word recognition processes. Using the visual world paradigm, we evaluated online spoken word recognition in adolescents who varied in both basic language abilities and non-verbal cognitive abilities. Eye movements to target, cohort and rhyme objects were monitored during spoken word recognition, as an index of lexical activation. Adolescents with poor language skills showed fewer looks to the target and more fixations to the cohort and rhyme competitors. These results were compared to a number of variants of the TRACE model (McClelland & Elman, 1986) that were constructed to test a range of theoretical approaches to language impairment: impairments at sensory and phonological levels; vocabulary size, and generalized slowing. None of the existing approaches were strongly supported, and variation in lexical decay offered the best fit. Thus, basic word recognition processes like lexical decay may offer a new way to characterize processing differences in language impairment.

A nonword repetition task for speakers with misarticulations: the Syllable Repetition Task (SRT)

PURPOSE

Conceptual and methodological confounds occur when non(sense) word repetition tasks are administered to speakers who do not have the target speech sounds in their phonetic inventories or who habitually misarticulate targeted speech sounds. In this article, the authors (a) describe a nonword repetition task, the Syllable Repetiton Task (SRT), that eliminates this confound and (b) report findings from 3 validity studies.

METHOD

Ninety-five preschool children with speech delay and 63 with typical speech completed an assessment battery that included the Nonword Repetition Task (NRT; C. Dollaghan & T. F. Campbell, 1998) and the SRT. SRT stimuli include only 4 of the earliest occurring consonants and 1 early occurring vowel.

RESULTS

Study 1 findings indicated that the SRT eliminated the speech confound in nonword testing with speakers who misarticulate. Study 2 findings indicated that the accuracy of the SRT to identify expressive language impairment was comparable to findings for the NRT. Study 3 findings illustrated the SRT's potential to interrogate speech processing constraints underlying poor nonword repetition accuracy. Results supported both memorial and auditory-perceptual encoding constraints underlying nonword repetition errors in children with speech-language impairment.

CONCLUSION

The SRT appears to be a psychometrically stable and substantively informative nonword repetition task for emerging genetic research and other research with speakers who misarticulate.

Perception of tone and aspiration contrasts in Chinese children with dyslexia

BACKGROUND

Previous research has shown a relationship between speech perception and dyslexia in alphabetic writing. In these studies speech perception was measured using phonemes, a prominent feature of alphabetic languages. Given the primary importance of lexical tone in Chinese language processing, we tested the extent to which lexical tone and aspiration, two fundamental dimensions of Cantonese speech not represented in writing, would distinguish dyslexic from non-dyslexic 8-year-old Chinese children. Tone and aspiration were tested in addition to other phonological processing skills across groups to determine the importance of different aspects of phonological sensitivity in relation to reading disability.

METHODS

Dyslexic children and age-matched and reading-level controls were tested on their categorical perception of minimal pairs contrasting in tone and aspiration, phonological awareness, rapid digit naming, and Chinese reading abilities.

RESULTS

While performing similarly to reading-level controls, dyslexic children perceived tone and aspiration contrasts less categorically and accurately than age-matched controls. They also performed more poorly than the age-matched controls on rapid digit naming and a measure of phonological awareness testing children's sensitivity to different grain size units.

CONCLUSIONS

Dyslexia in non-alphabetic Chinese correlates with the categorical organization and accuracy of Cantonese speech perception, along the tone and aspiration dimensions. This association with reading is mediated by its association with phonological awareness. Therefore, dyslexia is universally at least partly a function of basic speech and phonological processes independent of whether the speech dimensions in question are coded in writing.

Early language development of children at familial risk of dyslexia: speech perception and production

Speech perception and speech production were examined in 3-year-old Dutch children at familial risk of developing dyslexia. Their performance in speech sound categorisation and their production of words was compared to that of age-matched children with specific language impairment (SLI) and typically developing controls. We found that speech perception and production performance of children with SLI and children at familial risk of dyslexia was poorer than that of controls. The results of the at-risk and SLI-group were highly similar. Analysis of the individual data revealed that both groups contained subgroups with good and poorly performing children. Furthermore, their impaired expressive phonology seemed to be related to a deficit in speech perception. The findings indicate that both dyslexia and SLI can be explained by a multi-risk model which includes cognitive processes as well as genetic factors.

LEARNING OUTCOMES

As a result of reading this paper the reader will be able to (1) learn about the relationship between language and literacy; (2) recognise that dyslexia and specific language impairment may show similar areas of language difficulties, and (3) understand that both disorders can be interpreted within a multirisk model, including cognitive processes as well as genetic factors.

Statistical learning in children with specific language impairment

PURPOSE

In this study, the authors examined (a) whether children with specific language impairment (SLI) can implicitly compute the probabilities of adjacent sound sequences, (b) if this ability is related to degree of exposure, (c) if it is domain specific or domain general and, (d) if it is related to vocabulary.

METHOD

Children with SLI and normal language controls (ages 6;5-14;4 [years;months]) listened to 21 min of a language in which transitional probabilities within words were higher than those between words. In a second study, children with SLI and Age-Nonverbal IQ matched controls (8;0-10;11) listened to the same language for 42 min and to a second 42 min "tone" language containing the identical statistical structure as the "speech" language.

RESULTS

After 21 min, the SLI group's performance was at chance, whereas performance for the control group was significantly greater than chance and significantly correlated with receptive and expressive vocabulary knowledge. In the 42-minute speech condition, the SLI group's performance was significantly greater than chance and correlated with receptive vocabulary but was no different from chance in the analogous 42-minute tone condition. Performance for the control group was again significantly greater than chance in 42-minute speech and tone conditions.

CONCLUSIONS

These findings suggest that poor implicit learning may underlie aspects of the language impairments in SLI.

Evaluation of a novel technique for assessing speech discrimination in children

Methods used to assess children's speech perception and recognition in the clinical setting are out of step with current methods used to investigate these experimentally. Traditional methods of assessing speech discrimination, such as picture pointing, yield accuracy scores which may fail to detect subtle perceptual difficulties. This paper will report a novel method of assessing speech input processing that uses measurement of children's eye movements to provide information on speed and confidence as well as accuracy in discriminating phonological contrasts. Participants were typically developing children aged 2-7 years. Pairs of pictures representing auditory minimal pairs which varied in type and degree of phonological contrast were presented on a computer screen while the child heard a word matching one of these pictures. The child's eye movements in response to these stimuli were videorecorded for subsequent analysis of duration and direction of gaze. The effects of age and stimulus type on eye gaze were examined. The results were compared with those of a traditional picture pointing task using the same stimuli. The informativeness of the novel technique is evaluated on the basis of the findings.

Uses and interpretations of non-word repetition tasks in children with and without specific language impairments (SLI)

BACKGROUND

The non-word repetition task (NRT) has gained wide acceptance in describing language acquisition in both children with normal language development (NL) and children with specific language impairments (SLI). This task has gained wide acceptance because it so closely matches the phonological component of word learning, and correlates with measures of phonological working memory, a deficit in which is hypothesized to underlie SLI.

AIMS/METHODS & PROCEDURES

Recent uses of the NRT seem to accept it as a measure of phonological working memory capacity in spite of the fact that researchers have consistently acknowledged that the task taps many language processes, including speech perception, phonological encoding, phonological memory, phonological assembly and articulation. This paper reviews the literature on the use of the non-word repetition task (NRT) in children with NL and children with SLI, emphasizing the component skills necessary for successful repetition.

MAIN CONTRIBUTION

For children with NL, discussion has focused on (1) the relationship between non-word repetition ability and vocabulary, and (2) lexical and sublexical influences on repetition accuracy. For children with SLI, discussion has focused on these factors as well, but has also considered other component skills that support non-word repetition. Researchers have examined speech perception and discrimination, phonological encoding, phonological memory, phonological assembly, motor planning, and articulation, and have found evidence that children with SLI exhibit impairments in each of these supporting skills.

CONCLUSIONS

Because repetition accuracy depends on lexical and sublexical properties, the NRT can be used to examine the structural properties of the lexicon in both children with NL and with SLI. Further, because the task taps so many underlying skills, it is a powerful tool that can be used to identify children with language impairments.

Basic auditory processing skills and specific language impairment: a new look at an old hypothesis

PURPOSE

To explore the sensitivity of children with specific language impairment (SLI) to amplitude-modulated and durational cues that are important for perceiving suprasegmental speech rhythm and stress patterns.

METHOD

Sixty-three children between 7 and 11 years of age were tested, 21 of whom had a diagnosis of SLI, 21 of whom were matched for chronological age to the SLI sample, and 21 of whom were matched for language age to the SLI sample. All children received a battery of nonspeech auditory processing tasks along with standardized measures of phonology and language.

RESULTS

As many as 70%-80% of children diagnosed with SLI were found to perform below the 5th percentile of age-matched controls in auditory processing tasks measuring sensitivity to amplitude envelope rise time and sound duration. Furthermore, individual differences in sensitivity to these cues predicted unique variance in language and literacy attainment, even when age, nonverbal IQ, and task-related (attentional) factors were controlled.

CONCLUSION

Many children with SLI have auditory processing difficulties, but for most children, these are not specific to brief, rapidly successive acoustic cues. Instead, sensitivity to durational and amplitude envelope cues appear to predict language and literacy outcomes more strongly. This finding now requires replication and exploration in languages other than English.

Children with specific language impairments perceive speech most categorically when tokens are natural and meaningful

PURPOSE

To examine perceptual deficits as a potential underlying cause of specific language impairments (SLI).

METHOD

Twenty-one children with SLI (8;7-11;11 [years;months]) and 21 age-matched controls participated in categorical perception tasks using four series of syllables for which perceived syllable-initial voicing varied. Series were either words or abstract nonword syllables and either synthesized or high-quality edited natural utterances. Children identified and discriminated (a) digitally edited tokens of naturally spoken "bowl"-"pole", (b) synthesized renditions of "bowl"-"pole", (c) natural "ba"-"pa", and (d) synthetic "ba"-"pa".

RESULTS

Identification crossover locations were the same for both groups of children, but there was modestly less accuracy on unambiguous endpoints for children with SLI. Planned comparisons revealed these effects to be limited to synthesized speech. Children with SLI showed overall reduced discrimination, but these effects were limited to abstract nonword syllables.

CONCLUSION

Overall, children with SLI perceived naturally spoken real words comparably to age-matched peers but showed impaired identification and discrimination of synthetic speech and of abstract syllables. Poor performance on speech perception tasks may result from task demands and stimulus properties, not perceptual deficits.