An investigation of speech perception in children with specific language impairment on a continuum of formant transition duration

Speech Perception Variability in Childhood Apraxia of Speech: Implications for Assessment and Intervention

PURPOSE

Beyond hallmark production deficits characterizing childhood apraxia of speech (CAS), largely attributed to disruption(s) in speech motor planning, children with CAS often present with co-occurring speech perception and language difficulties. Thus, careful consideration of the potential for speech perception difficulties to have cascading downstream effects on intervention responsiveness and real-life functioning for some children with CAS is highly important. The purpose of this tutorial was to consider the impact of speech perception abilities in children with CAS, which carries implications for caring for the needs of the whole child.

METHOD

This tutorial summarizes the current literature on speech perception and how it relates to speech production, language, and reading abilities for children with CAS. We include case illustrations that are adapted from real clinical scenarios illustrating how speech perception difficulties may impact some children with CAS and provide recommendations for incorporating speech perception into assessment and intervention practices.

RESULTS

Although speech perception difficulties do not seem to be a core deficit of CAS, they are strongly linked to language difficulties, which are highly prevalent among children with CAS. Speech perception and language difficulties are also associated with reading difficulties and risk for lower academic achievement.

CONCLUSIONS

Children with CAS who have co-occurring language difficulties likely also demonstrate speech perception deficits, which puts them at heightened risk for reading difficulties and struggles with academic achievement. Comprehensive assessment of children with CAS should address speech perception and production, language, and reading abilities, which carries important implications for multifaceted approaches to intervention.

Left hemisphere enhancement of auditory activation in language impaired children

Specific language impairment (SLI) is a developmental disorder linked to deficient auditory processing. In this magnetoencephalography (MEG) study we investigated a specific prolonged auditory response (N250m) that has been reported predominantly in children and is associated with level of language skills. We recorded auditory responses evoked by sine-wave tones presented alternately to the right and left ear of 9-10-year-old children with SLI (n = 10) and children with typical language development (n = 10). Source analysis was used to isolate the N250m response in the left and right hemisphere. In children with language impairment left-hemisphere N250m responses were enhanced compared to those of controls, while no group difference was found in the right hemisphere. Consequently, language impaired children lacked the typical right-ward asymmetry that was found in control children. Furthermore, left but not right hemisphere N250m responses correlated positively with performance on a phonological processing task in the SLI group exclusively, possibly signifying a compensatory mechanism for delayed maturation of language processing. These results suggest that enhanced left-hemisphere auditory activation reflects a core neurophysiological manifestation of developmental language disorders, and emphasize the relevance of this developmentally specific activation pattern for competent language development.

Speech perception in children with cochlear implants for continua varying in formant transition duration

PURPOSE

To examine the developmental course of labial and alveolar manner of articulation contrasts, and to determine how that course may be different for typically developing (TD) children with cochlear implants (CI).

METHOD

Eight young adults, eight TD 5-8 year-old children, and seven 5-8 year-old children with CIs participated. Labial /ba/-/wa/ and alveolar /da/-/ja/ continua stimuli were presented, with each continuum consisting of nine synthetic stimuli varying in F2 and F3 transition duration. Participants were asked to label the stimuli as either a stop or glide, and responses were analysed for phonetic boundaries and slopes.

RESULT

For the /ba/-/wa/ contrast, children with CIs required longer transition durations compared to TD children or adults to cross from one phoneme category to another. The children with CIs demonstrated less confidence in labelling the stimuli (i.e. less steep slopes) than the TD children or the adults. For the /da/-/ja/ contrast, the children with CIs showed less steep slope values than adults.

CONCLUSION

These results suggest that there are differences in the way TD children and children with CIs develop and maintain phonetic categories, perhaps differences in phonetic representation or in linking acoustic and phonetic representations.

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.

Specific Language Impairment: Evaluation and detection of differential psycholinguistic markers in phonology and morphosyntax in Spanish-speaking children

BACKGROUND

The diagnosis of Specific Language Impairment (SLI) is very complex, given the variety of clinical pictures described in this disorder. Knowledge about the linguistic markers of SLI can facilitate its differentiation from the normal profile of language development. These markers can also be used as tools that may improve diagnostic.

AIMS

To determine which psycholinguistic markers best discriminate Spanish-speaking children with SLI from children with typical language development.

METHOD AND PROCEDURE

The performance of 31 Spanish-speaking children with SLI was analysed using a battery of 13 psycholinguistic tasks organized into two areas: phonology and morphosyntax. The performance of the SLI group was compared to that of two subgroups of controls: aged matched (CA) and linguistically matched (CL).

OUTCOMES AND RESULTS

The data show that the SLI group performed worse than the CA subgroup on all 13 verbal tasks. However, the performance of the SLI group did not significantly differ from that of the CL subgroup on most (11/13) of the tasks. Stepwise discriminant analysis established the canonical function of three tasks (morphologic integration, sentence understanding and diadochokinesis) which significantly discriminated SLI from CA, with sensitivity 84% and specificity 90%.

CONCLUSIONS AND IMPLICATIONS

These results contribute to determining the psycholinguistic and clinical characteristics of SLI in Spanish-speaking children and provide some methods for screening assessment.

Visual Speech Perception in Children With Language Learning Impairments

PURPOSE

The purpose of the study was to assess the ability of children with developmental language learning impairments (LLIs) to use visual speech cues from the talking face.

METHOD

In this cross-sectional study, 41 typically developing children (mean age: 8 years 0 months, range: 4 years 5 months to 11 years 10 months) and 27 children with diagnosed LLI (mean age: 8 years 10 months, range: 5 years 2 months to 11 years 6 months) completed a silent speechreading task and a speech-in-noise task with and without visual support from the talking face. The speech-in-noise task involved the identification of a target word in a carrier sentence with a single competing speaker as a masker.

RESULTS

Children in the LLI group showed a deficit in speechreading when compared with their typically developing peers. Beyond the single-word level, this deficit became more apparent in older children. On the speech-in-noise task, a substantial benefit of visual cues was found regardless of age or group membership, although the LLI group showed an overall developmental delay in speech perception.

CONCLUSION

Although children with LLI were less accurate than their peers on the speechreading and speech-in noise-tasks, both groups were able to make equivalent use of visual cues to boost performance accuracy when listening in noise.

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.

ERPs reveal the temporal dynamics of auditory word recognition in specific language impairment

We used event-related potentials (ERPs) to compare auditory word recognition in children with specific language impairment (SLI group; N=14) to a group of typically developing children (TD group; N=14). Subjects were presented with pictures of items and heard auditory words that either matched or mismatched the pictures. Mismatches overlapped expected words in word-onset (cohort mismatches; see: DOLL, hear: dog), rhyme (CONE -bone), or were unrelated (SHELL -mug). In match trials, the SLI group showed a different pattern of N100 responses to auditory stimuli compared to the TD group, indicative of early auditory processing differences in SLI. However, the phonological mapping negativity (PMN) response to mismatching items was comparable across groups, suggesting that just like TD children, children with SLI are capable of establishing phonological expectations and detecting violations of these expectations in an online fashion. Perhaps most importantly, we observed a lack of attenuation of the N400 for rhyming words in the SLI group, which suggests that either these children were not as sensitive to rhyme similarity as their typically developing peers, or did not suppress lexical alternatives to the same extent. These findings help shed light on the underlying deficits responsible for SLI.

Audiovisual speech perception in children with developmental language disorder in degraded listening conditions

PURPOSE

The effect of the signal-to-noise ratio (SNR) on the perception of audiovisual speech in children with and without developmental language disorder (DLD) was investigated by varying the noise level and the sound intensity of acoustic speech. The main hypotheses were that the McGurk effect (in which incongruent visual speech alters the auditory speech percept) would be weaker for children with DLD than for controls and that it would get stronger with decreasing SNR in both groups.

METHOD

The participants were 8-year-old children with DLD and a sample of children with normal language development. In the McGurk stimuli, the consonant uttered by the voice differed from that articulated by the face. Three sound intensities (24, 36, and 48 dB) and noise levels (-12, 0, and +6 dB) were used. Perception of unisensory visual speech was also measured.

RESULTS

The children with DLD experienced a weak McGurk effect, that is, a weak influence of visual speech on audiovisual speech perception, which remained rather constant across SNR levels. The children with DLD were inaccurate at lipreading.

CONCLUSIONS

Children with DLD have problems in perceiving spoken consonants presented audiovisually and visually. The weaker McGurk effect could be accounted for by the poorer lipreading ability of children with DLD.

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.

Enhanced physiologic discriminability of stop consonants with prolonged formant transitions in awake monkeys based on the tonotopic organization of primary auditory cortex

Many children with specific language impairment (SLI) have difficulty in perceiving stop consonant-vowel syllables (e.g., /ba/, /ga/, /da/) with rapid formant transitions, but perform normally when formant transitions are extended in time. This influential observation has helped lead to the development of the auditory temporal processing hypothesis, which posits that SLI is causally related to the processing of rapidly changing sounds in aberrantly expanded windows of temporal integration. We tested a potential physiological basis for this observation by examining whether syllables varying in their consonant place of articulation (POA) with prolonged formant transitions would evoke better differentiated patterns of activation along the tonotopic axis of A1 in awake monkeys when compared to syllables with short formant transitions, especially for more prolonged windows of temporal integration. Amplitudes of multi-unit activity evoked by /ba/, /ga/, and /da/ were ranked according to predictions based on responses to tones centered at the spectral maxima of frication at syllable onset. Population responses representing consonant POA were predicted by the tone responses. Predictions were stronger for syllables with prolonged formant transitions, especially for longer windows of temporal integration. Relevance of findings to normal perception and that occurring in SLI are discussed.

Sustained selective attention skills of preschool children with specific language impairment: evidence for separate attentional capacities

PURPOSE

The present study was designed to investigate the performance of preschool children with specific language impairment (SLI) and their typically developing (TD) peers on sustained selective attention tasks.

METHOD

This study included 23 children diagnosed with SLI and 23 TD children matched for age, gender, and maternal education level. The children's sustained selective attention skills were assessed with different types of stimuli (visual, nonverbal-auditory, linguistic) under 2 attentional load conditions (high, low) using computerized tasks. A mixed design was used to compare children across groups and performance across tasks.

RESULTS

The SLI participants exhibited poorer performance than their peers on the sustained selective attention tasks presented in the auditory modality (linguistic and nonverbal-auditory) under the high attentional load conditions. Performance was comparable with their peers under the low attentional load conditions. The SLI group exhibited similar performance to their peers on the visual tasks regardless of attentional load.

CONCLUSION

These results support the notion of attention difficulties in preschool children with SLI and suggest separate attentional capacities for different stimulus modalities.

Language impairment is reflected in auditory evoked fields

Specific language impairment (SLI) is diagnosed when a child has problems in producing or understanding language despite having a normal IQ and there being no other obvious explanation. There can be several associated problems, and no single underlying cause has yet been identified. Some theories propose problems in auditory processing, specifically in the discrimination of sound frequency or rapid temporal frequency changes. We compared automatic cortical speech-sound processing and discrimination between a group of children with SLI and control children with normal language development (mean age: 6.6 years; range: 5-7 years). We measured auditory evoked magnetic fields using two sets of CV syllables, one with a changing consonant /da/ba/ga/ and another one with a changing vowel /su/so/sy/ in an oddball paradigm. The P1m responses for onsets of repetitive stimuli were weaker in the SLI group whereas no significant group differences were found in the mismatch responses. The results indicate that the SLI group, having weaker responses to the onsets of sounds, might have slightly depressed sensory encoding.