Abstract

Developmental dyslexia is a learning disorder marked by a difficulty in recognising and understanding written language. It is estimated that 7% of children who are otherwise of normal intelligence and without any obvious neurological damage are affected by developmental dyslexia, which can lead to impaired education and eventual quality of life. The theory that processing of language and music is shared by some parts of the brain is gaining support. It is understood that rhythm perception is important in both speech and music; studies have shown that children and adults with dyslexia are poor with respect to rhythmic timing. Much research has shown that the core difficulty in developmental dyslexia, across many languages, is one of sensing the pattern within speech sounds, so called, phonological awareness. This is the ability to hear-out the parts of a word, for example, to tell which word does not rhyme from the group: gap, nap, Jack. Specifically, it has been shown that sensitivity to the rise time of a sounds amplitude envelope is impaired for children with developmental dyslexia and poor phonological awareness, as well as linked to musical rhythm sensitivity. It is proposed that poor sensitivity to this part of the acoustic signal is common to both dyslexia and impaired rhythm perception. Relatively little is understood about the underlying brain mechanisms involved with phonological awareness. To be able to identify the core neural deficits underlying dyslexia could lead to improvements in educational interventions, possibly based on rhythm and music training.