Across languages, children with developmental dyslexia are known to have impaired lexical phonological representations. Here, we explore associations between learning new phonological representations, phonological awareness, and sensitivity to amplitude envelope onsets (rise time). We show that individual differences in learning novel phonological representations are related to individual differences in both rise time categorization and rise time discrimination when non-verbal IQ and short-term memory skills are controlled. This is consistent with the developmental claim that difficulties in the basic auditory processing of rise time cause difficulties in setting up the phonological lexicon from infancy, leading to impairments in phonological awareness.