Onomatopoeia - Repeating the phonetic syllables to form new words that tries to imitate the sounds it makes - like "tick - tick" or "tick-tock"
I believe and researched that AUM was worshiped in Egypt, Crete, Middle East, Greek, Italy, Ireland, Americas and Asia. There are many pointers including DNA, Linguistics and Archaeology.
OM is AUM. So someone chanting "AUM - AUM" is doing the "tap" or "effort of hard work" and "upAya" is "method" or it could be adjective "IYA".
So literally someone doing this hard work of process (of worshipping to obtain peace, happiness and salvation) will be described "AUM AUM TAP UPAYA" or "AUM AUM TAP IYA".
There are rules, where for polishing, nasals sounds cane be made of one kind or for musical effects can be made into different kinds. So "N" and "M" are the same family of nasal sounds.
