This book is an introduction to speech science attempting to cover the entire processes of human communication made by sound. Five authors, who have various backgrounds in areas such as linguistics, physiology, engineering, and computer science, introduce and explain the latest information from their viewpoints. The contents of this book are: 1) phonetics, 2) phonology, 3) biological foundation on speech production and perception by human beings, 4) speech analysis and speech synthesis using machines, and 5) speech recognition using machines.