Listeners bin continuous changes in the speech signal into phonetic categories but vary in how consistently/discretely they do so. Categorization may relate to speech-in-noise (SIN) perception. Yet, it is unclear if and how perceptual gradience, consistency, and other cognitive factors (e.g., working memory) collectively predict SIN performance. Here, we estimated perceptual gradiency and response consistency during vowel labeling and assessed working memory and SIN performance. We found perceptual consistency and working memory were the best predictors of listeners' SIN scores. Our findings emphasize the importance of perceptual consistency over categoricity for noise-degraded speech perception.