This project investigates the role of sound in the human perception of the non-human environment, focusing on human responses to the sounds of birds. Contrary to the view, commonly advanced in writings on human sensory perception, that vision and hearing are radically distinguished along the lines of a contrast between objective observation and subjective participation, we suggest that seeing is as much an experience of light as much as hearing is an experience of sound. Under what conditions, then, does sound enable us to hear things, as light enables us to see them? Our inquiry concentrates on five key issues: How do people come to attend to bird sounds? Are birds perceived, in the first place, as sounds or as objects that make sounds? What is the relation between recognising and classification the sounds of birds? How do people learn the skills of listening to, and identifying, bird sounds? How do bird sounds evoke place, time and season? Methods included: library research, a local bird sounds project in north-east Scotland, working with novice birders who are learning techniques of bird sound identification, comparative fieldwork in Brazil, consultation of extant web-sites and message-board discussions, interviews with both musicians and natural scientists who have incorporated the study of bird sounds into their work, and research with keepers of domestic aviary birds.