Low, under.Under the Helmholtz Octave Designation System, a name applied to the octave which extends from C 1 two octaves below the bass clef staff to B 1 one octave below the bass clef staff. The notes are indicated by uppercase letters with the subscript "1" ( C1, D 1, E 1, F 1, G 1, A 1, and B 1).This octave can also be designated with two uppercase letter (i.e. CC) or in the 1st octave under Acoustical Society of America system (i.e. C 1). The MIDI Octave Designation System has two versions, one where note 1 (8.176 Hz) is octave "0" making the Contra octave the second octave (i.e. C2), and the other with note 1 (8.176 Hz) at octave "-2" making the Contra octave the fundamental octave (i.e. C0). The indication 8vb (shown below) can be used to represent the same pitches without as many ledger lines.against. as a prefix, means an octave below, e.g., contrabassoon