Why does the Renaissance flute play everything one octave higher? 

Very nice, video. The audio seems very quiet, though.

This was really interesting! The volume was low tho, so it was hard to hear you speak without earphones.

So in other words, the flute is being played an octave higher than the written music? This is something we often do with treble (alto) recorder when playing renaissance music.

What you say reminds me of the cornetto: for me it is so hard to start a low note but could start any high note as I please. I could approach a low note within a phrase but not start it, after playing higher notes. This made me remark that the low notes of the cornetto’s first octave are not used often…

Very interesting

In my practical sense, maybe the repertoire of the time didn't like writing above outside the staff with ledger but still demanded the characteristic of the renaissance flute what is sounded at higher pitch. Even the recorder instrument is not notated to how it sounds. Not like I ever played early music though. If the line is expected to be doubled by the instrument then it would be 'economical' to share parts without writing each individual part out for each player. Why write out doubled parts when you can have musicians perceive and perform them with their judgment? You can take any excerpt and play above or below the line. This is called counterpoint however octaves are way easier to learn and double. In fact, it is required that a good musician has this feat as well as understanding clefs and intervals.

Isn’t the tenor flute very close to the voice, perhaps more so than an alto recorder? Wouldn’t it make sense that if the cantus was sung, the counterpoint of the flute would be happening above it, further distinguishing itself from the human voice?