Founded in 1994 by two AIDS activists, Ultra-red is a sound art collective of artists, researchers, and organizers engaged in social movements focused on migration, anti-racism, education, tenants’ rights, and HIV/AIDS politics. Through its “Militant Sound Investigation,” a method of listening that questions the presumed fidelity of audio recordings, the collective explores acoustic space as enunciative of social relations. With its practice spanning radio, performance, recording, installation, and publishing, Ultra-red contributes to the organization and analysis of political struggles, using sound-based research and acoustic mapping.