Auditory processing skills and phonological representation in Dyslexic children

Abstract

It is now well-established that there is a causal connection between children's phonological skills and their acquisition of reading and spelling. Here we study low-level auditory processes that may underpin the development of phonological representations in children. Dyslexic and control children were given a battery of phonological tasks, reading and spelling tasks and auditory processing tasks. Potential relations between deficits in dyslexic performance in the auditory processing tasks and phonological awareness were explored. It was found that individual differences in auditory tasks requiring amplitude envelope rise time processing explained significant variance in phonological processing. It is argued that developmentally, amplitude envelope cues may be primary in establishing well-specified phonological representations, as these cues should yield important rhythmic and syllable-level information about speech.

Auditory sensory deficits in developmental dyslexia: A longitudinal ERP study

“…On the basis of prior behavioural work (Goswami et al, 2002(Goswami et al, , 2010bHämäläinen et al, 2009;Muneaux et al, 2004;Richardson et al, 2004;Surányi et al, 2009), we expected group effects to be strongest for rise time, however this was not the case. Rather, the most conservative explanation of the ERPs is that children with dyslexia have general differences in auditory neural processing in comparison to children of the same age who do not have dyslexia.…”

“…Discrimination of rise, intensity and duration was designed to be close to normative behavioural thresholds in previous experiments (Richardson et al, 2004;Thomson and Goswami, 2008;Goswami et al, 2010a,b), in order to avoid supra-threshold effects on the MMN which may obscure differences between the groups. As can be seen by comparing Table 1 with Supplemental Table 1, the discriminations chosen were however sub-threshold for normative rise time discrimination for this particular group of participants at test point 1 (control threshold, 95 ms) although not at test point 2 (control threshold, 45 ms), were sub-threshold for normative intensity discrimination at test point 1 (control threshold 4 dB) but not test point 2 (control threshold 4 dB), and were sub-threshold for normative duration discrimination at both test points (control thresholds 92 ms and 87 ms respectively).…”

“…One possibility that has been widely investigated at the sensory level is that children with dyslexia have auditory processing difficulties (e.g., Tallal, 1980;Witton et al, 1998;Goswami et al, 2002). One auditory sensory deficit that is found in children with dyslexia across languages is inefficient processing of the rate of change of amplitude envelopes (also called rise time; Goswami et al, 2002Goswami et al, , 2010aHämäläinen et al, 2009;Muneaux et al, 2004;Richardson et al, 2004;Surányi et al, 2009). Here, we extend the investigation of rise time processing in dyslexia to the neural level by using EEG.…”

“…This may indicate that the amplitude rise time deficit found in developmental dyslexia is indicative of impairments in distinguishing the different modulation frequency ranges in speech, particularly the lower frequency modulations (around 4 Hz) associated with syllables (see Goswami, 2011). However, rise time is a complex percept, and the behavioural work in dyslexia to date has used linear envelopes rather than the exponential rise times characteristic of natural speech (see Goswami et al, 2002;Richardson et al, 2004). When linear envelopes are used, sounds with more extended rise times have shorter duration steadystates and also take longer to reach peak intensity.…”

“…Measures of rise time, intensity and duration had been used in prior behavioural studies of children with dyslexia, with consistent impairments found for rise time only (Richardson et al, 2004;Thomson and Goswami, 2008;Goswami et al, 2010b). Behavioural thresholds from these prior studies were used to inform the stimulus choices made here.…”