A Neural Basis for Phonological Awareness? An Oscillatory Temporal-Sampling Perspective

Abstract

Individual differences in phonological awareness, or speech-sound awareness, between children predict reading and spelling development across languages. Recent advances in our understanding of the neural basis of speech encoding suggest one possible sensory and neural basis for these individual differences. This article describes an oscillatory theoretical perspective based on sampling of the speech stream by networks of cells that vary in excitability at different temporal rates. These variations in neural excitability (oscillations) may align to similar energy variations (such as amplitude modulations, AMs) in speech, helping to encode the signal. Indeed, cell networks in auditory cortex form an oscillatory hierarchy, which mirrors an AM hierarchy found in rhythmic speech. Mappings between these hierarchies may support parsing of the speech signal into phonological units. Oscillations at approximately 2 Hz may help identify stressed syllables, used to convey meaning in all languages, while oscillations at approximately 5 Hz may help identify syllables. Behavioral research suggests that the rhythmic patterning of stressed syllables may provide an acoustic “skeleton” for phonological development across languages. As well as helping to explain individual differences, an oscillatory framework offers new targets for improving children’s phonological development, for example, via multimodal rhythmic activities.