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Product
Review:
Real Sound Synthesis for Interactive Applications by Perry
R. Cook
Real
Sound Synthesis for Interactive Applications describes elementary
and advanced techniques to simulate the audio components of dynamic
systems using physics. While the book is not specifically directed
toward game developers, the application to game development is clear.
The book's organization is easily to follow through three sections
detailing digital audio, sound modeling, and simulation of real-world
instruments.
The
first section (chapters 1-3) defines digital audio, compression,
wave synthesis, and simple filtering techniques. These chapters
serve as the foundation for what follows, defining common asset
formats and techniques currently used in games.
The
second section (chapters 4-8) introduces sound modeling through
simplified physical systems, such as an ideal spring, and Fourier
series equations. While an understanding of college physics and
calculus is helpful (especially if you'd like to code these methods),
the book doesn't require it or get bogged down in theory or mathematical
proofs.
The
last section (chapters 7-16) provides physics equations that allow
for the simulation of real-world instruments (string instruments,
tubes, and multi-dimensional objects). Each chapter describes a
different system based on Fourier construction, filtering, and physics-based
equations. It's the heart of the book and most interesting.
The
clean organizational layout made it easy for me to refer back to
previous sections when I felt the need. In many cases, however,
I found the writing to be a little too condensed and wished for
a paragraph describing a concept rather than the sentence provided.
Cook does supply references at the end of each chapter for those
readers seeking additional detail.
The
book also includes a CD containing audio samples of the topics discussed
throughout the book. While reading the book, it was useful to be
able to hear the point made or technique used in the text. The CD
also contains Cook's sound synthesis toolkit and several examples
of instruments highlighted in the last section.
Unfortunately,
real-time sound synthesis in games currently has a limited place.
Due to the complex calculations of Fourier series, fast digital
signal processor chips are required to simulate the audio effects
without impacting the rest of the game. Minimally, filters and other
simple routines outlined in the book can be written for target hardware
to accomplish specialized effects, but this is nothing radically
new.
However,
Cook's research in simulating audio is extremely exciting. During
the calculation of an object's dynamic behavior (such as collision
response, striking, falling, and moving), a minimal additional amount
of time can be spent to determine the audio effects. According to
Cook's findings, this amount is generally less than 5 percent of
the total time required to simulate an object's physical behavior.
Admittedly, these calculations are on the order of minutes versus
milliseconds, but eventually Moore's law will catch up and simplifications
will allow unparalleled audio effects in conjunction with physical
simulation.
Developers
and sound designers interested in the math and physics of creating
real-time sounds should pick up this book. Those interested in a
fascinating look at the mechanisms of dynamically producing sound
might also want to give it a read, provided it's with the understanding
that the direct applicability to games is at least few years away.
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