Preface

It is over ten years since I wrote the first edition of this book and it seems today that almost everything about the subject has changed except for the laws of physics. As a result there are many things in this edition which have changed beyond recognition, contrasting with some basics which have not changed at all.

Back then I felt that the approach of many technical books limited them to mathematically inclined readers of a certain level, and I resolved to write something where the mathematics were replaced with plain English and where statements were replaced by explanations. I also felt strongly that theories would be much more readily understood if they were illustrated by examples in practical equipment. In short, I wrote a book which I would have wanted to read myself.

Although I was pleased with the way the book turned out, I was not prepared for either the quality or the quantity of the acclaim which it received. To have one’s first book commonly referred to as a bible is a great reward for the effort which went into it, and convinced me that the radical approach taken should be maintained in any future edition.

The great success of the first two editions of this book had the effect that I was closely identified with digital audio rather than audio in general. This is partly my own fault because the first edition assumed that the reader would have an existing understanding of analog audio equipment to which the digital knowledge could be added.

Over ten years of teaching digital audio and video technology has shown me that the people who have the most difficulty with digital are those who didn’t understand analog in the first place. Today, digital audio is no longer a specialist subject, but has become the norm. It is impossible to function in the audio industry without some knowledge of it.

It follows that this book must change its focus and include more about the general subject of audio so that it is clear what is going to be digitized and how well it needs to be done. The approach of this edition is to begin with a treatment of the human hearing system which defines the necessary quality, and to move on to see how that quality can be reached in the digital domain. Of course, in real systems economic or practical considerations may prevent the goal of transparency being reached, but this is best done with an accurate knowledge of what is being lost. A full chapter is devoted to obtaining the highest quality from a digital audio system.

Another inevitable consequence of the universality of digital audio is that the proportion of those involved who fully grasp the fundamentals must fall. In such a climate pseudoscience can flourish where technically misleading statements are made for the sole purpose of selling equipment. Such statements cause confusion to genuine students and waste the time of their teachers.

The reader may be confident that no such statements appear in this book. On the contrary, this book contains barely any statements at all. Statements are not useful because they don’t give confidence. Instead this book contains explanations and arguments from first principles which the reader can follow and gain confidence that what is being said is true. Further confidence can be gained by seeking out the many references quoted. Essentially this is an introductory book, a theory book, an applications book and a reference book all in one.

One of the aspects of digital audio which still fascinates the author is the wide range of disciplines that it embraces. There is still no explanation of the mechanism designers use to combine techologies to make an affordable product. Whilst the theory we use is scientifically based, putting it into practice remains an art, hence the title.