Increased speech contrast induced by sensorimotor adaptation to a non-uniform auditory perturbation

When auditory feedback is perturbed in a consistent way, speakers learn to adjust their speech to compensate, a process known as sensorimotor adaptation. While this paradigm has been highly informative in understanding speech sensorimotor control, its ability to induce behaviorally-relevant changes in speech that affect communication effectiveness remains unclear. Here, we examine human speakers’ ability to compensate for a non-uniform perturbation field which reduces vowel distinctiveness by shifting all vowels toward the center of vowel space. Speakers adapted to this non-uniform shift, learning to produce corner vowels with increased vowel space area and vowel contrast to partially overcome the apparent centralization. The increase in vowel contrast occurred without a concomitant increase in duration and persisted after the feedback shift was removed, including after a 10-minute silent period. These findings establish the validity of a sensorimotor adaptation paradigm to increase vowel contrast, an outcome that has the potential to enhance intelligibility.