Ever since Richard Taruskin pointed to Steve Reich’s use of survivor testimony in hailing the composer’s Different Trains (1988) as ‘the only adequate musical response … to the Holocaust’, composers of Western art music have embraced musicalised testimony as a form of truthful sonic witnessing to historical conflict. This persistent connection between music and testimony often is framed as documenting memories of trauma, yet this interpretation does not address the reciprocal relationships between the presumed truths of sound and its aesthetic presentation in music. Driven by Hannah Arendt’s claim that ‘factual truths are never compellingly true’, in this essay I trace the interpenetration of documentary sound and music as conveying a compelling reality or truth. This is followed by examples of testimonial witnesses in works by Philip Miller and Mary Kouyoumdjian. Finally, I reflect on the roles that testimonial music might play in imparting such compelling truths in connection with societal conflict.