A soundsnake is a hallucination that occurs while tripping on lsd. The sound is motile, reverberating at frequencies and oscillations within ones head, as it passes through from ear to ear like a ripping of reality, like a fine toothed comb, being flicked by careful hands. Now this ripping sound sometimes opens a way to hear the static of the universe. Through that static constructions and interpretations become possible. One begins to hear conversations, which manifest themselves like seeds from sound into distinct emotional, visual, and immersion.
Jeff Noon, also a psychonaut has written much about dreamsnakes and the sort, as well as his Cobralingus book--all of which detail a similar hallucinatory experience.