This evening I took the shotgun mic into the basement and placed it a few inches from the base of our washing machine.
I left the bass up, not too high, because the sound is very lulling. I'm always interested in the industrial nature of sound (or the aural nature of machines?) Is there an "industrial" sound?
see Throbbing Gristle, Bruce Gilbert, Monte Cazazza, etc.
One thing to think about when encountering repetative sound environments: is this truly repetition? or (to quote Stein) insistence? Listen long enough and you will notice, not only an evolution of textures, but you'll be able to better pick out particulars hidden in the monotony.