Expert opinions differ on what to call the Octaves - that’s all If you google search for midi note’s you will find different answers.
from MIDI.org, midi specification:
from http://openmusictheory.com/pitches.html
“… the International Standards Organization (ISO) system for register designations. In that system, middle C (the first ledger line above the bass staff or the first ledger line below the treble staff) is C4 . An octave higher than middle C is C5, and an octave lower than middle C is C3.”
But in Ableton and Bitwig - Middle C (aka ISO C4) is MIDI note 72.
Here’s an answer from KMI:
" There are actually multiple MIDI note number to note name conventions — different companies follow different standards. KMI follows the C3=60 paradigm (as does Ableton, Logic, MainStage, and more), while other companies follow the C4=60 paradigm (Native Instruments and others). It’s even possible to run into a C5=60 standard, but that is much more rare.
If all MIDI notes appear to be an octave off, it simply means that there are two different note naming standards involved. it’s only the note number that matters — the name is irrelevant."
Also, more in-depth: Scientific pitch notation - Wikipedia