In museum exhibition design, the experiential aspects of virtual reality and other immersive technologies are increasingly being explored. This study contributes to these explorations, focusing on the role of hearing and sound in visitors’ experiences of a hybrid virtual environment designed for an architecture museum exhibition. Physically, the environment consisted of a full-scale, multi-level structure installed in a large gallery space. Virtually, visitors ‘switched’ between being in a contemporary villa and a natural shoreline biotope while moving in the physical installation, experiencing and comparing nature and architecture as “parallel realities." This study investigates visitors’ experiences of realism in the soundscape and how this contributed to the immersive experience. Exit interviews with randomly selected visitors on the sound experience (N = 82) are primary data for this study. Visitor responses to questions related to sound (N = 320) and data collected from interviews and observations of recruited visitor pairs (N = 16) are complementary data. The study finds that visitors considered sound essential to the high degree of realism they experienced in the hybrid virtual environment, in the sense of “being there,” and that this was dependent on signal types that were appropriate in type and variation. Additionally, relevant to exhibition design practice, issues of quality and delivery methods had minimal impact on the visitor experience.