One of the specifications I gave to contributors to the first edition was that, as far as possible, articles should not be too closely related to current equipment and techniques so that the book wouldn’t go out of date quickly.
To a large extent this has worked well, but, of course, there have been major changes in some fields. For example, Perceptual Coding has acquired a much greater importance than it had in 1994 so there has been a need for some new material.
Consequently all the available authors have looked carefully at their original contributions and had the opportunity to revise where necessary. Some of the revisions have been very minor, but others have been quite significant.
A few of the original authors ...