Ess r2 was written by Krister Olsson, employing the following public domain/WOL code:

Pink noise generation: based on an algorithm by Phil Burk

Reverb: based on the Freeverb algorithm by Jezar Wakefield

Pitch shifting (maintaining tempo): based on code copyright 1999-2003 Stephan M. Bernsee

FFT: based on code by Toxi

FFT helper routines: based on code by Marius Watz

Additional thanks to Tim Johnson for helping sort out the glitches in r1.