Working Memory Modulates Auditory Perceptual Sensitivity During Speech Planning

Working memory plays a critical role in speech production. However, how working memory influences speech systems remains unclear. This study aimed to investigate how maintaining a vowel in working memory alters perceptual sensitivity during speech planning.

Thirty-two healthy adults participated in two experiments. In Experiment 1 (n = 15), participants completed a speaking task while performing a concurrent working memory manipulation. In Experiment 2 (n = 17), participants completed both speaking and reading tasks, each performed alongside a concurrent working memory manipulation. In speaking blocks, participants produced monosyllabic words, whereas in reading blocks, they silently read them. During each trial, participants categorized an auditory probe stimulus positioned between the vowels /ɛ/ and /æ/. Trials were classified as congruent or incongruent depending on whether the vowel maintained in working memory matched the auditory target. Perceptual sensitivity and speech variability were measured across conditions.

In the speaking condition, participants showed higher perceptual sensitivity in congruent trials compared to incongruent trials, indicating that maintaining a vowel in working memory biased auditory target perception during speech planning. No such effect was observed in the reading condition. Additionally, participants exhibited a trend of reduced speech variability in congruent compared to incongruent trials, suggesting that working memory modulates speech outcome. No significant relationship was found between changes in perceptual sensitivity and speech variability across subjects.

These findings suggest that maintaining a vowel in working memory shapes auditory target representations and modulates speech outcomes. This study provides novel evidence for the influence of working memory on speech systems.