When counting in 6/8 or 12/8, traditionally we count the eight notes as:
1+a 2+a in 6/8 and 1+a 2+a 3+a 4+a in 12/8
This works well when we only have to count eighth notes, however when we also have to count sixteenth notes, traditional counting methods don't allow us enough syllables. So, instead, I think we are better of going back to counting the eighth notes as numbers, i.e 1 2 3 4 5 6 in 6.8 and then we can use the syllable '+' for any in between sixteenth notes.
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