This is a randomized, double-blind, placebo-controlled, 3-arm, parallel-group, multi-center study. Participants will attend a Screening Visit to confirm eligibility and then return to the clinic within 14 days to be randomized into the study. Randomized participants will receive a single dose of their allocated study intervention (225 mg BNC210, 675 mg BNC210 or placebo) and approximately 1 hour later participate in a speaking challenge. After 1 week, a safety follow-up assessment will be conducted by phone/video conference.