“SoundMagic Spectral is a freeware suite of 24 Audio Unit plug-ins that implement real-time spectral processing of sound”
When I start brainstorming for a sound design task, first set of tools that pop up in my mind is Michael Norris Spectral plugins. This toolbox lets you dive into spectral morphing to granular processing, soundscape design to drone making.
“This groundbreaking set of effects give you unprecedented control and creativity in the processing of audio, whether from static audio files or live audio streams. SoundMagic Spectral builds on the work of the OS 9 software known as SoundMagic DSP, and takes it to even more exotic sonic realms.”
Here is another use of spectral plugins in a tutorial by Trifonic,
If you are a sound designer or electronic music producer, I highly recommend this tool set.