17th century South African music
Found my answers in The Notation of Polyphonic Music 900-1600 https://archive.org/details/notationofpolyph00apel/page/94/mode/2up
Sent to Distributed Proofreaders postprocessor:
"The beginning flags are rests written on bar lines. The drums are five bars long. The voices are four bars long.
The second symbol in the drums is two whole notes written on a bar line. Because diamonds are always stacked, The side arrows indicate the bottom note is too high. This is a symbol for a dual drum roll.
The third symbol in both systems indicates a coincidence of various parts. In this case, both parts are each a bar long; another dual drum roll and a measure long vocal on one note.
The black diamonds are half the value of the white diamonds. Because the parts were written separately, the drums were converted to eighth notes in the voice and drums MP3 to be heard together correctly.
You'll have to use the original images in the book. I haven't found a way to recreate them in MuseScore.
I made MP3s for drums alone, voice alone, and one of voice and drums together.
Thanks, everyone. <3