How do cognitive processes influence speaking? We used a novel variant of the Stroop test to measure whether cognitiveinhibition could modulate acoustic properties of speech. Participants named the color of words in three categories: 1)congruent (e.g. red written in red), 2) color-incongruent (e.g. green written in red), and 3) vowel-incongruent, withphonetic properties that partially matched the text color (e.g. rid written in red). We hypothesized that the cognitive effortof inhibiting reading in this third conditionsaying red, not ridcould affect the acoustics of the spoken response. A classicStroop effect was evident: congruent trials were faster than color-incongruent trials. Interestingly, vowel-incongruent trialsdid not show this reaction time difference, but spoken vowels from these trials were systematically biased away from thevisually-presented text. Thus, the inhibition of a competing target is manifest in an accentuation of the acoustic contrastbetween the spoken and inhibited words.