This book introduces the concept of sonic virtuality, a theory of sound that positions it as an emergent perception within a framework of virtuality. In its opposition to the acoustic or standard definition of sound, that sound is a sound wave, the thesis builds its case for a sonic aggregate as the virtual cloud of potentials from which the sound as perception emerges. This is argued for from a broad interdisciplinary perspective that assesses evidence and thinking from philosophy; acoustics and psychoacoustics; auditory science and neurology; sensation, perception, and cognition; cross-modality; writings on truth, knowledge, imagination, hallucination, belief, and alief; ontology and epistemology; embodied cognition; computer games and similar environments; acoustic ecology and ecological acoustics; sound design; and theories of reality, actuality, and virtuality. Throughout, the book is at pains to not only assess from many approaches this new way of conceptualizing sound but also to demonstrate the practical applications and advantages of the ideas and models that accompany it. This is accomplished through numerous illustrative examples that not only reference everyday experiences but also probe the future of audio design in the context of new and developing technologies.