Augmented tunings are used for stringed instruments, especially guitars, and for wind instruments. For guitars, augmented tunings are called major thirds tunings.
Major-thirds (M3) tunings are unconventional open tunings, in which the open strings form an augmented triad; in M3 tunings, the augmented fifth replaces the perfect fifth of the major triad of conventional open-tunings.[1] Consequently M3 tunings are also called (open) augmented-fifth tunings (in French "La guitare #5, majeure quinte augmentée").[2] Unfortunately, the open augmented-chord sounds dissonant to audiences who are accustomed to standard tuning.[3]
Sethares, Bill (2001). "Regular tunings". Alternate tuning guide(PDF). Madison, Wisconsin: University of Wisconsin; Department of Electrical Engineering. pp. 52–67. Retrieved 19 May 2012.