Polymicrotonality
Polymicrotonality is the use of multiple tuning systems in the same piece.[1] Ivor Darreg also calls this polysystemic. [2]
Techniques
With equal divisions of the octave (or any other interval) tuning systems, polymicrotonality is achieved via the equal division which is the least common multiple of the two (or more) systems being played. Highly composite edos are rich sources of polysystemicism as they have more divisors than any number before them, and thus provide strong opportunities of using multiple systems in one piece.
Compositions
In Search of Perfect Consonance Roland GR-20 re-tuned to Arabic 17 note Pythagorean tuning and electric guitar in 12 equal by Chris Vaisvil => performance details
Santa Barbara Shipwreck 19 edo guitar with 12 edo synthesizer by Paul H. Muller and Chris Vaisvil
Seventeen Years in the Sixties - 17 edo guitar, 12 edo 5 string bass & drums by Chris Vaisvil => Details
The following from a tuning survey by Chris Vaisvil
The Mouth Opens to Speak Bill Bremmer Shining Brow tuning and 12 edo<br>
The Lumma Cryptic Boethiuss Chromatic <br>
immoderate moderations Gramham Breed blues scale in 22 edo plus 12 edo<br>
untitled 1 12 edo and 17-limit quasi meantone in a major<br>
Venusian Wedding Band by Carlo Serafini (blog entry)