This octave can also be designated as the 3rd octave under Acoustical Society of America system (i.e. C3). The MIDI Octave Designation System has two versions, one where note 1 (8.176 Hz) is octave "0" making the Small octave the fourth octave (i.e. C4), and the other with note 1 (8.176 Hz) at octave "-2" making the Small octave the second octave (i.e. C2).
Play Small Octave Example (MIDI file format)