Numerical
Sound Synthesis Companion Page
This book, out in October 2009, is about physical modelling sound synthesis;
or, more technically, the generation of sound based on differential equation
models of musical objects. An “object,” here, could be a standard
acoustic musical instrument, such as a clarinet or cymbal, or, more generally,
a mechanical or electromechanical audio effect. The general goal is to generate
sound which possesses all the richness of acoustically-produced sound---perhaps
emulating an existing instrument, but perhaps an entirely new imaginary virtual
instrument. A good analogy is to the current advances in computer graphics
rendering using physical models (of bouncing balls, water waves, etc.)
There are lots of ways of
going about designing physical modelling sound synthesis routines;
probably the best known are digital waveguides, developed initially by Julius Smith at
CCRMA, which are a great match to certain
instrument types (1D, nearly linear, nearly dispersionless)---for much more on
waveguides, see Julius’s comprehensive on-line publication. Another
well-known technique is modal synthesis, which was developed into the
Modalys/MOSAIC environment at IRCAM.
This book is devoted to time-domain methods, and in particular,
finite difference schemes, which are perhaps unfamiliar to the audio engineer;
there are no delay lines, digital filters, Fourier transforms, or banks of
oscillators employed! The great things about these methods are their
generality, their fidelity to the physics of musical instruments and that they
can be very easy to construct---there are no hypotheses about travelling waves,
or linearity, or modal frequencies. The downside is that they may cost more to
run, in terms of computational effort, and that there are all sorts of quirky
design issues, such as numerical stability, bandwidth limitation and others to
contend with! Is the sound any better? You’ll have to judge for
yourselves, from the numerous sound examples given in the example pages below.
This companion page is intended as a non-technical repository of
demonstrations and sound examples, as well as a few pedagogical code examples,
to give you a flavor of how these methods work, and the kinds of sounds they
produce. I’ll keep adding to this page periodically. Any comments should
go to me, at the email address given on my main page.
As far as the book goes, you can take a look at the introductory chapter, the table of
contents,
and the index if you like…
Some freely available sample material:
Some example topics,
including movies and sound examples:
Nonlinear shell vibration: cymbals
A modular percussion environment
Reed Wind instruments