Book excerpt: From a founding figure in the field, the definitive introduction to an exciting new science. What do the sounds of a chorus of tropical birds and frogs, a clap of thunder, and a cacophony of urban traffic have in common? They are all components of a soundscape, acoustic environments that have been identified by scientists as a combination of the biophony, geophony, and anthrophony, respectively, of all of Earth’s sound sources. As sound is a ubiquitous occurrence in nature, it is actively sensed by most animals and is an important way for them to understand how their environment is changing. For humans, environmental sound is a major factor in creating a psychological sense of place, and many forms of sonic expression by people embed knowledge and culture. In this book, soundscape ecology pioneer Bryan C. Pijanowski presents the definitive text for both students and practitioners who are seeking to engage with this thrilling new field. Principles of Soundscape Ecology clearly outlines soundscape ecology’s critical foundations, key concepts, methods, and applications. Fundamentals include concise and valuable descriptions of the physics of sound as well as a thorough elucidation of all sounds that occur on Earth. Pijanowski also presents a rich overview of the ecological, sociocultural, and technical theories that support this new science, illustrating the breadth of this amazingly transdisciplinary field. In methods, he describes the principles of data mining, signal processing, and mixed methods approaches used to study soundscapes in ecological, social, or socio-ecological contexts. The final section focuses on terrestrial, aquatic, urban, and music applications, demonstrating soundscape ecology’s utility in nearly all spaces.