one-line
[English]
Under the Helmholtz Octave Designation System, a name applied to the octave which extends from middle C (or C1) below the treble clef staff to B1 on the treble clef staff. The notes are indicated by lowercase letters with the superscript "1" (c1, d1, e1, f1, g1, a1, and b1).
This octave can also be designated with one hash mark (i.e. C') or in the 4th octave with Scientific Pitch Notation (SPN) using uppercase letters with octave "4" (C4, D4, E4, F4, G4, A4, and B4). This is also known as American Standard Pitch Notation (ASPN) and was defined by the Acoustical Society of America.
The MIDI Octave Designation System has two versions, one where note 1 (8.176 Hz) is octave "0" making the One-line octave the fifth octave (i.e. C5), and the other with note 1 (8.176 Hz) at octave "-2" making the One-line octave the third octave (i.e. C3).
The indication 8vb (shown below) can be used to represent the same pitches. Typically, this indication (8vb) would not be used with the treble clef staff, and since most of the notes in this octave are on the staff, using this designation would not make reading the notes any easier for the performer.
