In tarab music, the ability to play or sing in correct pitch is another requisite for creating ecstatically effective performances. Essentially, few theoretical works describe the ecstatic role of intonation, despite the abundance of treatises and text-books that deal with tuning and modal scales. Furthermore, in such sources melodic intervals are most often presented in terms of the microtonally crude, largely Western inspired theoretical system of equal-tempered half-steps, three-quarter steps, whole steps, augmented seconds, and so on, intervals derived from a theoretical scale of 24 equal quarter-tones per octave. In actual practice however, tarab music exhibits an intricate and highly patterned system of intonation.
AJ Racy “Making Music in the Arab World” pg. 106
See previous post, Microtones