Calling a music microtonal is really such an unfortunate and misleading thing and belies alot of the assumptions that we make (in the world of Western Music) about how another culture’s music is organized.
Basically we take as a standard Western diatonicism and when discussing other culture’s scale systems (the idea of a “scale” is also problematic for similar reasons) we reference some normative idea of what an interval between two tones or notes means. So if we have a normative tonal system, with half steps being the smallest distance between two tones, then technically, if we have a scale system with intervals smaller than a half step that would be “microtonal” scale system (and vice versa for a “macrotonal” scale system).
This works fine for scale systems by a number of avant garde composers in the Western Art Music tradition (e.g. Harry Partch, Lejaren Hiller, Glenn Branca) who have worked out scales with intervals that are smaller than a half step. But this really makes no sense when applied to, say, Arabic Music.
Sure, in the history of Arabic Music we have theorists that have attempted to reconstruct a theory of scales using a 24-note per octave quarter tone scale as the basis for Arabic Music (and Persian, Turkish, Azeri Musics) but there are technically no scales that use a quarter tone in between two intervals. There are any number of tones that fall in between the notes of a Western Scale (often called “neutral tones” to contrast with “sharp tones,” “flat tones,” and “natural tones”) but the stepwise motion to those neutral tones and from those neutral tones usually consist of an interval that falls somewhere in between a half step and a whole step.
So with no intervals smaller than the smallest interval in a Western scale, what exactly do we mean by Arabic Music being “microtonal” anyway?
I’m sure I’ll have more to post about this later, but felt the need to ponder this as I’m learning a number of new Arabic tunes for an upcoming performance–and realizing that the Western tuning of Cellos isn’t really optimal for playing and I might have to adopt an Arabic or Middle Eastern tuning or settle with using fingerings that are terribly unidiomatic for cello playing (which won’t be the first time for me).