I am sitting in a backwards room

I am sitting in a backwards room different from the one you are in now. I am recording the sound of my speaking voice and I am going to play it back into the backwards room again and again until the backward frequencies of the room reinforce themselves so that any illegibility of my speech, with perhaps the exception of the rhythm of the backwards room, is destroyed. What you will hear, then, are the natural frequencies of the backwards room articulated by speech. I regard this activity not so much as a demonstration of a physical fact, but, more as a way to smooth out any asymmetries my speech might have.

Analog granular synthesis

might be possible if a read head from a reel-to-reel or cassette player were used like the wheel of a hurdy-gurdy and the tape its strings.