Acknowledgements Dr Keith Holland; lecturer in acoustics at the Institute of Sound and Vibra- tion Research, with whom I have worked closely for over 20 years. His work is evident throughout this book, and he was responsible for about 150 of the measurements presented in the figures. It is an honour to have him so deeply involved in a work such as this. Sergio Castro AMIOA, who assembled the entire artwork for the book and who was responsible for the graphics for around 200 of the figures. He has been a close friend and colleague ever since I designed his studio, Planta Sonica, in Vigo, Spain in 1985. Janet Payne, who not only provoked me into writing this book, but who undertook to put onto a word processor literally thousands of pages of manu- script. For anybody who knows what my handwriting is like, the enormity of the task will be self-evident. Tim Goodyer and David Bell, for Chapter 17. It can be difficult for a person such as me to enthuse about something to which they cannot 100% commit themselves, but it would have been unjust to write a half-hearted