Introduction to Physical Signal Models

This book is about techniques for building real-time computational physical models of musical instruments and audio effects. So, why would anyone want to do this, and what exactly is a ``computational physical model''?

There are several reasons one might prefer a computational model in place of its real-world counterpart:

• A virtual musical instrument (or audio effect) is typically much less expensive than the corresponding real instrument (effect). Consider, for example, the relative expense of a piano versus its simulation in software. (We discuss real-time piano modeling in §9.4.)

• Different instruments can share common controllers (such as keyboards, wheels, pedals, etc.). Any number of virtual instruments and/or effects can be quickly loaded as ``presets''.

• Sound quality (``signal to noise ratio'') can far exceed what is possible with a recording. This is because we can use any number of bits per sample, rendering the ``noise floor'' completely inaudible at all times.

• Software implementations are exactly repeatable. They never need to be ``tuned'' or ``calibrated'' like real-world devices.

• It is useful to be able to ``archive'' and periodically revive rare or obsolete devices in virtual form.

• The future evolution of virtual devices is less constrained than that of real devices.