The only thing the editors of this volume should have changed is its title. A more precise title would be Audio pearls. That’s exactly what almost all of the mid-sized papers in this work are, in the true spirit of another wonderful series, Graphics gems. Continuing the tradition from the first volume [1], this volume presents additional processing techniques, explores new areas, and teaches some basic concepts.

The book begins with a section of tips on how to make good recordings in various environments. The next section goes into the technicalities of sound synthesis, more precisely oscillator control and subtractive synthesis. Section 3 is a continuation from Volume 1, in that it continues with a discussion of basic signal processing operators like filters and transforms. A particularly interesting paper in this section is the concluding chapter, on integer arithmetic-based fast Fourier transforms (FFTs).

Section 4 is about spatialization. It doesn’t exactly reveal what happens inside your Sennheiser Toltec processor, but covers the basic ideas. Low-level must-know techniques, such as circular first-in-first-outs (FIFOs) and framing, are covered in some detail in section 5. Section 6 presents some popular tools, such as the SoX library, and the wonderful synthesis toolkit by Perry Cook. It was a surprise to see a page on the QED package; it is neither unique nor the best (but it’s just a page).

Music theory is the topic of section 7. This may be foreign lingo for many engineers, as well as a foreign approach. For example, the authors explain what consonance and dissonance are, and how they fit in the sound scale, but there is no discussion of what physically happens, or, to be more precise, what psycho-physically happens. Auditory displays and auditory feedback are central to section 8, on sound design. The final section, section 9, reads almost like a Scientific American article on sounds in nature. It is very instructive. A very useful glossary of audio terminology concludes the book.

My final impression of the book series (from its two first volumes) is that it is similar to the Graphics gems series; it may not be essential reading, but one misses a lot by not reading at least a few chapters of it.