Next FScape version 3.14 / Mellite 3.13 will contain new feedback UGens. Here is a test with the feedback loop consisting of a Hilbert transform based frequency shifter and a delay, the shift moving the signal down 30 Hz in each iteration. There is an anti-aliasing high pass filter as well. The input signal is just 10 seconds of microphone signal initially picked up, my voice making some screeching sounds. As the process evolves, some interesting changes in timbre occur, notably some extreme energies are coming down from Nyquist, perhaps due to some ringing or other artefacts. The video has a gap in the middle because the computer would freeze (I suspect it was some problem of the screen recorder). The code is quite experimental, as one has to take care to enable sufficient buffering so that the DSP graph is flowing uninterruptedly.