Listening is an act that helps us understand where we are. At its most basic level, it’s a fundamental part of our biology. The rush of excitement we may feel from the surround sound in a movie theatre or an electronic music concert connects us to some of our most primal instincts. Early in our evolution, the ability to hear sound in space helped us navigate our environment and survive. Today, it is central to so many aspects of our lives that one might be surprised to learn that the mere idea that sound is spatial was not widely accepted or studied in the scientific community until the nineteenth century, as Gascia Ouzounian details in her compelling new book, Stereophonica. From this point of departure, when binaural audition (or ‘hearing in stereo’) becomes an object of scientific study, Ouzounian charts a course through the proliferation of interest in spatial sound in the twentieth century. The book recounts the development of military acoustic defence technologies and sonic warfare, medical and communications technologies, and the new art forms of electroacoustic music, spatial music, and sound art. From these historical accounts, she traces the growth of the new fields of acoustic ecology and urban sound studies. While Stereophonica is not intended as an exhaustive survey of the vast topic of sound and space, it presents a fascinating window into the relationship between the two, reflecting the plurality of meanings that ‘space’ can have in relation to sound. As she writes in her introduction, it can be “understood in physical, sensorial, geographical, social, and political terms.” Ouzounian’s own interdisciplinary background allows her to weave through this network of interconnected fields with intrigue and colour. She writes with infectious enthusiasm, beginning from the first chapter’s absorbing accounts of early experiments in sound propagation, involving eclectic situations ranging from the firing of grenades as subjects listened underwater to a subject listening through a metal wire held in their teeth. The book captures the often enchanting and mysterious qualities of spatial sound, animated by discussions of the echo and its role in mythology, spirituality, and aesthetics. Ouzounian’s examination of the way that spatial sound has dazzled and beguiled the human imagination throughout history progresses naturally to its impact on art. Stereophonica looks more specifically at spatial audio in twentieth-century music and sound art, especially through the mid-century evolution and proliferation of electroacoustic music. As an electroacoustic composer and sound artist, I share in Ouzounian’s fascination with the subject, which will also likely be of particular interest to readers of Circuit. While many practitioners and enthusiasts of these and related art forms are attracted to the liberating potential of spatial sound, it is often presented in utopic terms: the ‘magic’ and abstraction of art is often sequestered from the reality of human society and the natural world. Stereophonica reminds us that they are deeply interlinked. Ouzounian details this link through her discussion of the development of acoustic technology, ranging from stethoscopes to telephones to sound locators used to detect aircraft during the First World War. Beyond the technological and scientific advancements that these and other developments offered, the specialized forms of ‘spatial ear training’ that have emerged from them have dramatically influenced not only the ways we listen, but the ways that we conceptualize the act of listening itself. While we can trace a link between the pleasure of listening to music on headphones with the life-saving technology of the differential stethoscope, we can also see the way spatial audio has developed through and toward more nefarious applications. Beyond the perhaps more evident horrors of warfare and surveillance, …