All of the actors' dialogue was dubbed through additional dialogue recording—a common practice in Italian filmmaking at the time. On set, each actor spoke their native language (for instance, Harper, Valli, and Bennett spoke English; Casini, Bosé, Valli, and Bucci spoke Italian; and several others spoke German). Argento expressed disappointment over the fact that Harper's voice, which he liked, was not heard in the Italian market because she was dubbed in Italian by another actress. The dubbing was overseen by Ted Rusoff, a prolific voiceover artist based in Rome who supervised English-language dubbing for numerous European genre films including Argento's follow-up to "Suspiria", "Inferno".