This monograph project is a history of listening. It takes as its departure point the often-mocked, even hated, music of waiting spaces, that has become more ubiquitous than ever. In particular, it focuses on the formation of new perceptual systems in relation to the introduction of new sounds into both personal and public space through the development of recording and replay technology over the course of the twentieth century. This study of the co-development of modern, technology-dependent background music and the active cultivation of new forms of listening (by inventors, marketers, composers, and listeners themselves) also informs larger questions about the relationship between individuals’ and communities’ understanding of their environment and their (often indirect) experience of it. This is ultimately a story of the construction of sonic spaces, both perceptual and material. It lies at the intersection of history of science, technology, psychology, and marketing, and environmental history. From the very first efforts at recording and replay technology, scientists developed new understandings of the sensory perception of sound — how individuals listened and the bodily effects of sound despite inattention — that fueled the development of new consumer products. Science contributed to a new musical aesthetic and a new form of listening in a very explicit and deliberate way. Sonifying Space will show how science contributed to the development of new sounds and new listening practices, fundamentally altering the soundscape of the twentieth century.