@Purple, speedTom: Thanks for the comments! Yes, I gave myself a "get out of jail free" card, I know, by claiming up front that this was experimental. I think I have a better sense now of what these particular aspects of music can and cannot be called upon to do.
I *am* sorely tempted to add an additional layer of content by constructing a vocal to go with it--not a "song" per se, which implies too much, but definitely a human voice (spoken? sung? Vocaloid???) that will draw in the listener's ear, and let the single-pitch tricks do their work in the background.