Subcortical differentiation of stop consonants relates to reading and speech-in-noise perception

Abstract

Children with reading impairments have deficits in phonological awareness, phonemic categorization, speech-in-noise perception, and psychophysical tasks such as frequency and temporal discrimination. Many of these children also exhibit abnormal encoding of speech stimuli in the auditory brainstem, even though responses to click stimuli are normal. In typically developing children the auditory brainstem response reflects acoustic differences between contrastive stop consonants. The current study investigated whether this subcortical differentiation of stop consonants was related to reading ability and speech-in-noise performance. Across a group of children with a wide range of reading ability, the subcortical differentiation of 3 speech stimuli ([ba], [da], [ga]) was found to be correlated with phonological awareness, reading, and speech-in-noise perception, with better performers exhibiting greater differences among responses to the 3 syllables. When subjects were categorized into terciles based on phonological awareness and speech-in-noise performance, the top-performing third in each grouping had greater subcortical differentiation than the bottom third. These results are consistent with the view that the neural processes underlying phonological awareness and speech-in-noise perception depend on reciprocal interactions between cognitive and perceptual processes.brainstem ͉ dyslexia ͉ electrophysiology ͉ experience-dependent plasticity ͉ learning impairment L earning impairments, primarily reading disorders, are among the most prevalently diagnosed exceptionalities in school-aged children, affecting Ϸ 5% to 7% of the population (1). These impairments coincide with a number of perceptual deficits including inordinate difficulty perceiving speech in noise as well as neural encoding deficits in the auditory system. In typically developing children, differences in contrastive speech stimuli are encoded subcortically (2), but the possible relationship between subcortical encoding of stimulus differences and reading ability has not been previously explored.Behavioral Impairments. Children with reading impairments often show deficits in phonological processing, which may be caused by degraded phonological representations or an inability to access these representations effectively (3)(4)(5). This population also exhibits impairments in speech sound discrimination (i.e., contrastive syllables) relative to controls matched for age and reading level (6, 7), suggesting that impairments are not simply caused by a maturational delay. These effects are especially prevalent for place of articulation and voice onset time contrasts, which reflect dynamic spectral and temporal contrasts, respectively. Perceptual discrimination deficits seem to be limited to the rapid spectral transitions between consonants and vowels and are not found for steady-state vowels or when formant transitions are lengthened (8-10). Moreover, when presented with between-and within-phonemic category judgments, typically developing children successfully di...

Improving neural response to sound improves reading

“…These results demonstrate that assistive listening devices improve the neurophysiological representation of speech, specifically the rapid spectrotemporal components that are most vulnerable to noise. This latter finding is particularly interesting because it is formant transitions within speech syllables that have been shown in both behavioral and physiological studies to be most impaired in children with language and reading disorders (3,7). These data support a growing body of research suggesting that there may be a developmental continuum beginning in infancy that links individual differences in rapid auditory processing to individual differences in language development and subsequently to reading and other literacy skills.…”

Music Enrichment Programs Improve the Neural Encoding of Speech in At-Risk Children

“…These influences converge to make auditory midbrain a hub of cognitive, motor, and sensory processing. We speculate that top-down attentional and cognitive modulations caused an activity-driven enhancement in midbrain function, which progressively (i.e., with more training) drove the changes we observed (Polley et al, 2006;Hornickel et al, 2009;Bajo et al, 2010;Kraus and Chandrasekaran, 2010;Bajo and King, 2012). Uniquely, making music engages these systems in a positive, reinforcing, and active manner that offers neuroplastic potential beyond everyday listening experiences.…”

“…This suggests that music training transferred to non-music listening settings to influence automatic auditory processing. Importantly, these improvements were in processes that are important for everyday communication: previous investigations have revealed that, as groups, children who are better readers and children who hear better in noise show stronger neural distinctions of these same syllables (Hornickel et al, 2009;White-Schwoch and Kraus, 2013). These findings therefore provide support for the efficacy of community and co-curricular music programs to engender improvements in nervous system function.…”

“…Two synthesized, voiced consonant-vowel syllables, [ba] and [ga], differing only in the onset frequency of the second formant, were delivered to the right ear via insert earphones at 80 dB SPL. See (Hornickel et al, 2009) for a complete acoustic description of the syllables. Six thousand presentations of each syllable were presented in alternating polarity at a rate of 4.35/s.…”

“…It is thought that music training can effect structural and functional neural changes (i.e., experience-dependent plasticity; Kraus and Chandrasekaran, 2010;Patel, 2011;Herholz and Zatorre, 2012;Zatorre, 2013) because music engages widely distributed sensory, cognitive, and reward networks in the brainthe very networks whose integration drives neuroplasticity. However, only a small number of longitudinal studies have described a direct effect of music training (Fujioka et al, 2006;Moreno et al, 2009;Johnson et al, 2013;Tierney et al, 2013;Chobert et al, 2014) and debates persist concerning innate differences between musicians and non-musicians versus a causal role for music training (Corrigall et al, 2013;Zatorre, 2013); although there is encouraging longitudinal evidence for the potential of music training to engender improvements in automatic sound processing in children in this age range (Putkinen et al, 2014).…”