Messa di Voce augments the speech, shouts and songs produced by two virtuoso vocalists with real-time interactive visualizations. The project touches on themes of abstract communication, synaesthetic relationships, cartoon language, and writing and scoring systems, within the context of a sophisticated, playful, and virtuosic audiovisual narrative. Custom software transforms every vocal nuance into correspondingly complex, subtly differentiated and highly expressive graphics. Messa di Voce lies at an intersection of human and technological performance extremes, melding the unpredictable spontaneity and extended vocal techniques of human improvisers with the latest in computer vision and speech analysis technologies. Utterly wordless, yet profoundly verbal, Messa di Voce is designed to provoke questions about the meaning and effects of speech sounds, speech acts, and the immersive environment of language.