Stochastic modulation of the parallel feedback comb filter.
This is the outcome of numerous experiments in parameterized randomness influencing a dynamic equilibrium of the feedback system, and it is slowly, but steadily growing into a complete musical instrument. It is one of my first approaches to parametric modelling of sound textures.
Here's how it works. The comb filter is a simple delay line with a feedback loop. The delay time is modulated by a stochastic function generator. The function generator is a random point process, interpolated at the output, with a few parameters to control the range and speed of the modulation. The result is a dynamic, evolving sound texture, be it a subtle timbre addition or an experimental soundscape (as in the sound demo above).