Aberrismic theory
In groundfault's aberrismic theory, an aberrisma is a type of scale step which can be added to a scale pattern to turn it into a scale of one rank higher. Aberrismas are a new category of melodic steps that are smaller than the steps in the original scale, which are prototypically whole tones and semitones; the typical range for an aberrisma is 20 to 60 cents, with optimal size approximately 40 cents according to groundfault. Examples of ternary patterns that can be made by adding aberrismas to diatonic scales are:
- pinedye (5L2m1s or 1s)
- diasem (5L2m2s or 2s)
- blackdye (5L2m3s or 3s)
- diamech (5L2m4s or 4s)
- 5L2m5s (or 5s)
Aberrismic theory and RTT
Certain scales with aberrismas may be endowed with JI interpretations via RTT temperaments, such as equal temperaments. Under groundfault's use of RTT, the aberrisma tends to become 81/80 in a 2.3.5 context and a 64/63 in a 2.3.7 context. Thus aberrismic scales that admit more accurate 2.3.5.7 temperament interpretations and temper neither 81/80 nor 64/63, such as 5L2m5s, tend to identify 81/80 and 64/63, tempering out 5120/5103.
At times, a scale pattern has varying temperaments according to the tuning. For example, 5L2m3s may be given the temperament structure of either untempered 2.3.5 or Flutterpyth temperament.