Sensitivity to amplitude envelope rise time in infancy and vocabulary development at 3 years: A significant relationship.

Here we report, for the first time, a relationship between sensitivity to amplitude envelope rise time in infants and their later vocabulary development. Recent research in auditory neuroscience has revealed that amplitude envelope rise time plays a mechanistic role in speech encoding. Accordingly, individual differences in infant discrimination of amplitude envelope rise times could be expected to relate to individual differences in language acquisition. A group of 50 infants taking part in a longitudinal study contributed rise time discrimination thresholds when aged 7 and 10 months, and their vocabulary development was measured at 3 years. Experimental measures of phonological sensitivity were also administered at 3 years. Linear mixed effect models taking rise time sensitivity as the dependent variable, and controlling for non-verbal IQ, showed significant predictive effects for vocabulary at 3 years, but not for the phonological sensitivity measures. The significant longitudinal relationship between amplitude envelope rise time discrimination and vocabulary development suggests that early rise time discrimination abilities have an impact on speech processing by infants.Australian Research Counci

A neural oscillations perspective on phonological development and phonological processing in developmental dyslexia

Children’s ability to reflect upon and manipulate the sounds in words (’phonological awareness’) develops as part of natural language acquisition, supports reading acquisition, and develops further as reading and spelling are learned. Children with developmental dyslexia typically have impairments in phonological awareness. Many developmental factors contribute to individual differences in phonological development. One important source of individual differences may be the child’s sensory/neural processing of the speech signal from an amplitude modulation (~ energy or intensity variation) perspective, which may affect the quality of the sensory/neural representations (’phonological representations’) that support phonological awareness. During speech encoding, brain electrical rhythms (oscillations, rhythmic variations in neural excitability) re-calibrate their temporal activity to be in time with rhythmic energy variations in the speech signal. The accuracy of this neural alignment or ’entrainment’ process is related to speech intelligibility. Recent neural studies demonstrate atypical oscillatory function at slower rates in children with developmental dyslexia. Potential relations with the development of phonological awareness by children with dyslexia are discussed.Medical Research Council, G0400574 and G090237

Enhanced Syllable Discrimination Thresholds in Musicians

Speech processing inherently relies on the perception of specific, rapidly changing spectral and temporal acoustic features. Advanced acoustic perception is also integral to musical expertise, and accordingly several studies have demonstrated a significant relationship between musical training and superior processing of various aspects of speech. Speech and music appear to overlap in spectral and temporal features; however, it remains unclear which of these acoustic features, crucial for speech processing, are most closely associated with musical training. The present study examined the perceptual acuity of musicians to the acoustic components of speech necessary for intra-phonemic discrimination of synthetic syllables. We compared musicians and non-musicians on discrimination thresholds of three synthetic speech syllable continua that varied in their spectral and temporal discrimination demands, specifically voice onset time (VOT) and amplitude envelope cues in the temporal domain. Musicians demonstrated superior discrimination only for syllables that required resolution of temporal cues. Furthermore, performance on the temporal syllable continua positively correlated with the length and intensity of musical training. These findings support one potential mechanism by which musical training may selectively enhance speech perception, namely by reinforcing temporal acuity and/or perception of amplitude rise time, and implications for the translation of musical training to long-term linguistic abilities.Grammy FoundationWilliam F. Milton Fun

Sensory theories of developmental dyslexia: three challenges for research.

Recent years have seen the publication of a range of new theories suggesting that the basis of dyslexia might be sensory dysfunction. In this Opinion article, the evidence for and against several prominent sensory theories of dyslexia is closely scrutinized. Contrary to the causal claims being made, my analysis suggests that many proposed sensory deficits might result from the effects of reduced reading experience on the dyslexic brain. I therefore suggest that longitudinal studies of sensory processing, beginning in infancy, are required to successfully identify the neural basis of developmental dyslexia. Such studies could have a powerful impact on remediation.This is the accepted manuscript. The final version is available from NPG at http://www.nature.com/nrn/journal/v16/n1/abs/nrn3836.html

Locus of orthographic effects in spoken word recognition: Novel insights from the neighbour generation task

International audiencePrevious research has found that orthographic information can influence auditory word recognition. However, there is still debate about the locus of this effect (lexical versus nonlexical, strategic versus automatic). In the present study, we explored whether orthographic effects in auditory word recognition could be structural-residual effects that reflect changes in the quality or specificity of phonological representations during learning to read. To address this possibility, the neighbour generation task was used. This task is particularly well suited to explore the off-line nature of phonological representations. Indeed, in two experiments, we found that orthographic information affected the nature of phonological representations. Participants produced phonographic neighbours (i.e., words that share both orthographic and phonological neighbourhoods) significantly more often than would be expected by chance. The existence of an orthography effect in an off-line phonological task therefore suggests that orthographic information participates in the specification of phonological representations

Neighborhood effects in auditory word recognition: Phonological competition and orthographic facilitation

International audienceThe present study investigated phonological and orthographic neighborhood effects in auditory word. recognition in French. In an auditory lexical decision task, phonological neighborhood (PN) produced the standard inhibitory effect (words with many neighbors produced longer latencies and more errors than words with few neighbors). In contrast, orthographic neighborhood (ON) produced a facilitatory effect. In Experiment 2, the facilitatory ON effect was replicated while controlling for phonotactic probability, a variable that has previously been shown to produce facilitatory effects. In Experiment 3, the results were replicated in a shadowing task, ruling out the possibility that the ON effect results from a strategic and task-specific mechanism that might operate in the lexical decision task. It is argued that the PN effect reflects lexical competition between similar sounding words while the ON effect reflects the consistency of the sublexical mapping between phonology and orthography. The results join an accumulating number of studies suggesting that orthographic information influences auditory word recognition. (C) 2003 Elsevier Science (USA). All rights reserved