From Expert Sleepers:
Oomingmak is a pitch and envelope tracking (re)synthesis effect. It tracks the pitch and level of the incoming audio and uses them to synthesize an original sound using classic analogue style waveforms and subtractive synthesis and apply pitch modulation to the incoming audio while syncing to the original waveform. The oscillator can also be synced to the incoming audio, and the tracked envelope can be used to modulate the pitch, filter cut-off, and oscillator pulse-width. LFOs are also provided for further modulation possibilities. Two ring modulators are also provided, allowing two different combinations of the above sounds to be modulated against each other. As with all pitch-tracking devices, Oomingmak tends to work best on monophonic sound sources. It was designed particularly with the guitar in mind, in which case it tends to work well on solo lines rather than chords.