Preface

It seems inconceivable, but the editions of this book have arrived at number six. Clearly, decades ago, I had no idea what I was getting myself into. In 1984, at an Audio Engineering Society convention in New York, I presented a lecture on digital audio theory, using material from a course I had recently inaugurated at the University of Miami. After the lecture, I was thronged by engineers seeking more information on this wondrous new topic. An astute acquisitions editor noted the response and, in true Mephistophelean style, persuaded me to author a book on digital audio. After all, he explained, it would be simple to put everything down on paper. I naively accepted his bargain, and Principles of Digital Audio was published in 1985. The book’s publication fortuitously coincided with a tremendous surge in the development of digital audio technology.

Digital audio’s commercial popularity was matched only by the demand for explanations of its workings. Audio engineers, and students wishing to join their ranks, assimilated every scrap of information they could find, further propelling development of the science. The first edition gave way to the second, which stepped aside for the third, which submitted to the fourth, which yielded to the fifth. Despite occasional halfhearted promises that I would never write another edition, I could not ignore the fact that digital audio technology continued to expand, and there were increasing numbers of people eager to learn about it. Clearly, new editions became inevitable. As I slavishly authored one edition after another, I had only the royalty checks to console me. With the arrival of this sixth edition, I suppose I should start planning for the seventh.

Readers familiar with earlier editions will see the same patterns in the renovations in this latest installment. The essential nature of topics such as discrete time sampling has not changed, but our appreciation of them has. Similarly, the relative importance of topics continually changes; advances in technology diminish the magnitude of some issues, while magnifying others. Moreover, and even more significantly, in the years since the last edition digital audio theory has evolved and entirely new applications have been developed.

Examination of the contents of this sixth edition will show both losses and gains. A number of topics have been eliminated to conserve the page count; most notably and not surprisingly, the magnetic tape, DAT, and MiniDisc chapters have been dropped. In their place, numerous fresh topics have been introduced. For example, readers will find two new chapters on Blu-ray disc and speech coding, and the perceptual audio chapter (renamed “Low Bit-Rate Coding”) has been split into two chapters to allow more thorough discussions of this important topic. Also, the bibliography has been updated as needed.

As in past editions, a user-friendly approach has been retained, but the greater depth given to some material has somewhat increased the reading sophistication required. Of course, readers may pick and choose according to their level and need. Also, the wider scope of topics should satisfy a broader range of professional practitioners and students. One thing has not changed. This book is neither a compendium of every possible fact nor an advanced treatise. It is an introductory text that attempts to provide lucid explanations, and to strike that all-important balance between mere information and understanding. In other words, this is a learning tool, sharpened by years of refinement.

A final note: The material in this book stems from the work of the many pioneers and leaders in the field of digital audio technology. We owe a tremendous debt to those wonderfully creative and hard-working engineers who breathe life into digital audio. Clearly, their vision of the potential of this science is transforming both our industry and our society.

Ken C. Pohlmann
Durango, Colorado