When you want to create a synthetic rain forest and populate it with electronic animals, birds, and insects, Rurik Leffanta of xoxos has you covered. Having spent as much as he could afford on hardware synths, Leffanta says he became “determined to make freeware abundant so that anyone with a PC could make music.” His first VST plug-in for Windows was released in 2002, and there has been a steady stream ever since. Most are free, and those that are not are modestly priced.
The plug-in offerings run the gamut from algorithmic generators for MIDI and audio to sound effects, percussion, and music synthesizers to utilities and effects processors. Many of them use physical modeling, which makes them edgy, often chaotic, and generally great-sounding. Pair up Pling2 (plucked string) with KL Tract (vocals) for a synthetic duo you won't find in your favorite sampler. For drum sequencing, there is Ordinate, featuring three probability-based sequencers and a fourth sequencer to switch between them. Load up three drum samples, then follow Ordinate with the stutter-effect plug-in Muchacho, and you have a glitch-ready drum machine.
As for the aforementioned rain forest, the five plug-ins in the Sounds of Nature collection (free), winner of the KVR Developer Challenge 2007, together with the more recent Fauna ($33) do the job nicely (see Web Clip 1). Wind, Rain, and Thunder use filter-sculpted noise and modulation to emulate these sounds. Oscine Tract models the songbird's vocal tract and provides controls to shape and sculpt the chirping. Synsect routes an impulse clock through a series of resonant filters; it's truly buggy. Fauna uses waveguide, vocal-tract, and mass-spring modeling to produce animal vocal sounds. All of these plug-ins include an ample selection of presets along with extensive control panels.