MIDI note numbers are the unique numbers assigned to each note in the MIDI system. The MIDI numbering scheme uses 8 bits to identify all the notes. Therefore, there are 128 notes (28) that can be assigned in MIDI. Which note is which is not always straightforward. Let’s take a look at how Apple did it in Logic Studio 9.
The MIDI specification, as defined by the ISO (International Oraganization for Standardization), tells us that middle C is MIDI note number 60. All other notes are relative to this one. Therefore, MIDI note number 69 is the A above middle C (us used for 440Hz tuning). However, the specifications does not say which one is middle C. It turns out that various manufacturers place this middle C at different octaves. It usually is C3, C4 or C5.
In the case of Logic Studio, middle C is C3. This means that MIDI note number 0 is C-2 and that the highest note possible is G8 (using MIDI note number 127). This is usually not a problem as all most MIDI devices can usually be transposed up or down easily. It becomes a problem when you work in a complex project where sounds have not been defined for all 10 octaves and you hit a note and hear nothing… Yep, this is what happened to me. Therefore, as an easy reference, I am posting here the codes as used in Logic Studio 9.