This book was written in a period of six weeks whilst in residence as the Queen's Quest Visiting Scholar in the Music Department of Queen's University, Kingston, Ontario. It is a very much expanded version of a series of l ectures given in the Department on the subject of electronic music, though in fact it ranges over a field much wider than that normally encompassed by this term. The book grows out of my own musical experience over the past twenty years. Some of the ideas which I had been developing were fully confirmed during my experience of the course in computer music at the Institut de Recherche et Coordination Acoustique/Musique (IRCAM) in Paris during the summer of 1981.