Alcuin solves the problem

This guy, Alcuin. Not only did he run Charlemagne’s palace school, standardize calligraphy throughout the Holy Roman Empire, invent punctuation (like the question mark), set up the way Latin ought to be pronounced in church—he invented musical notation, too.

https://sites.google.com/a/umich.edu/from-tablet-to-tablet/final-projects/music-in-medieval-manuscripts

It got under Charlemagne’s skin that the Empire’s churches and monasteries sang the same hymns but each church gave a hymn a different tune. Charlemagne was relentless in his campaign to standardize everything. He put Alcuin in charge of making sure every choir sang the same tune. So Alcuin invented musical notation.

Musical notation was meant simply to record the tune of a song. Each note represents a particular pitch, depending on where it sits on a scale. The scale is horizontal lines—it’s a frame of reference. Notes at the top of the scale are sung higher than notes at the bottom of the scale. Thanks to Alcuin, choirs throughout the Empire knew exactly what tune to sing just by looking at the written musical notes.

Here are a couple of quick explanations of how musical notation works:
https://www.youtube.com/watch?v=ZN41d7Txcq0
https://www.youtube.com/watch?v=JFaKNR7eeJk

Back to the beginning of The Western Civ User’s Guide to Reading & Writing.