No abstract

Effective speech sound discrimination at preschool age is known to be a prerequisite for the development of language skills and later literacy acquisition. However, the speech specificity of cortical discrimination skills in small children is currently not known, as previous research has either studied speech functions without comparison with non-speech sounds, or used much simpler sounds such as harmonic or sinusoidal tones as control stimuli. We investigated the cortical discrimination of five syllable features (consonant, vowel, vowel duration, fundamental frequency, and intensity), covering both segmental and prosodic phonetic changes, and their acoustically matched non-speech counterparts in 63 6-year-old typically developed children, by using a multi-feature mismatch negativity (MMN) paradigm. Each of the five investigated features elicited a unique pattern of differentiating negativities: an early differentiating negativity, MMN, and a late differentiating negativity. All five studied features showed speech-related enhancement of at least one of these responses, suggesting experience-related neural commitment in both phonetic and prosodic speech processing. In addition, the cognitive performance and language skills of the children were tested extensively. The speech-related neural enhancement was positively associated with the level of performance in several neurocognitive tasks, indicating a relationship between successful establishment of cortical memory traces for speech and enhanced cognitive functioning. The results contribute to the understanding of typical developmental trajectories of linguistic vs. non-linguistic auditory skills, and provide a reference for future studies investigating deficits in language-related disorders at preschool age.

No abstract

Children's obligatory auditory event-related potentials (ERPs) to speech and nonspeech sounds have been shown to associate with reading performance in children at risk or with dyslexia and their controls. However, very little is known of the cognitive processes these responses reflect. To investigate this question, we recorded ERPs to semisynthetic syllables and their acoustically matched nonspeech counterparts in 63 typically developed preschoolers, and assessed their verbal skills with an extensive set of neurocognitive tests. P1 and N2 amplitudes were larger for nonspeech than speech stimuli, whereas the opposite was true for N4. Furthermore, left-lateralized P1s were associated with better phonological and prereading skills, and larger P1s to nonspeech than speech stimuli with poorer verbal reasoning performance. Moreover, left-lateralized N2s, and equal-sized N4s to both speech and nonspeech stimuli were associated with slower naming. In contrast, children with equal-sized N2 amplitudes at left and right scalp locations, and larger N4s for speech than nonspeech stimuli, performed fastest. We discuss the possibility that children’s ERPs reflect not only neural encoding of sounds, but also sound quality processing, memory-trace construction, and lexical access. The results also corroborate previous findings that speech and nonspeech sounds are processed by at least partially distinct neural substrates.

ObjectiveThe aim of the present study was to investigate speech processing development in children with normal hearing (NH) and cochlear implants (CI) groups using a multifeature event-related potential (ERP) paradigm. Singing is associated to enhanced attention and speech perception. Therefore, it’s connection to ERPs was investigated in the CI group.MethodsThe paradigm included five change types in a pseudoword: two easy- (duration, gap) and three difficult-to-detect (vowel, pitch, intensity) with CIs. The positive mismatch responses (pMMR), mismatch negativity (MMN), P3a and late differentiating negativity (LDN) responses of preschoolers (below 6 years 9 months) and schoolchildren (above 6 years 9 months) with NH or CIs at two time points (T1, T2) were investigated with Linear Mixed Modeling (LMM). For the CI group, the association of singing at home and ERP development was modeled with LMM.ResultsOverall, responses elicited by the easy- and difficult to detect changes differed between the CI and NH groups. Compared to the NH group, the CI group had smaller MMNs to vowel duration changes and gaps, larger P3a responses to gaps, and larger pMMRs and smaller LDNs to vowel identity changes. Preschoolers had smaller P3a responses and larger LDNs to gaps, and larger pMMRs to vowel identity changes than schoolchildren. In addition, the pMMRs to gaps increased from T1 to T2 in preschoolers. More parental singing in the CI group was associated with increasing pMMR and less parental singing with decreasing P3a amplitudes from T1 to T2.ConclusionThe multifeature paradigm is suitable for assessing cortical speech processing development in children. In children with CIs, cortical discrimination is often reflected in pMMR and P3a responses, and in MMN and LDN responses in children with NH. Moreover, the cortical speech discrimination of children with CIs is develops late, and over time and age, their speech sound change processing changes as does the processing of children with NH. Importantly, multisensory activities such as parental singing can lead to improvement in the discrimination and attention shifting toward speech changes in children with CIs. These novel results should be taken into account in future research and rehabilitation.