Challenges to Speech Perception Impair Phonological Short-Term Memory

Poor performance on measures of phonological processing is common to both Developmental Language Disorder (DLD) and dyslexia. Perceptual accounts characterise this phonological dysfunction as the result of auditory deficits at lower levels of the speech processing hierarchy, which may impair discrimination of speech sounds. However, a causal link between perceptual acuity for speech sounds and phonological performance has not been sufficiently established. We investigated whether challenges to speech perception can impair performance on a standard phonological task, in adults with normal language function. We used an audio-morphing procedure to create speech tokens with varying phonetic ambiguity. These formed the stimuli for an auditory letter span task (N = 36). Recall of high-ambiguity letters sequences was significantly impaired in comparison to low-ambiguity sequences, when stimuli were created by morphing two letters. We conclude that perceptually challenging speech can be more difficult to maintain in short-term memory.