Three-line octave

Two octaves above middle C

In the older German system the notes carry three strokes because you count the octaves upwards from the small c: c′ is middle C of the one-line octave, c″ lies an octave above, c‴ a further one. In the scientific notation, which this glossary uses in the music lines, c‴ is C6 and the standard pitch is A4. Each octave doubles the frequency, so C6 has twice as many vibrations per second as C5, namely 1046.5 Hz against 523.25 Hz.

The frequencies

All the values follow from the standard pitch A4 = 440 Hz and equal division: each semitone is the twelfth root of two, about 1.0595, times the one before. The C6 lies three semitones above the A5, whose frequency is 880 Hz, and gives, rounded, 1046.5 Hz. The table summarises the seven notes of the octave.

Who plays and sings there

The three-line octave belongs to the everyday life of the violin, whose range reaches into the four-line octave, and of the flute, which reaches it without effort. For singing voices it is the range of coloratura sopranos. The F6 with 1396.9 Hz is the famous highest note of the Queen of the Night in Mozart's “Die Zauberflöte”.

In the notation it becomes confusing high above the staff, because many ledger lines are needed. Such passages are therefore often written an octave lower with the octave sign 8va placed above. The sign stands for “ottava alta” and means: play an octave higher than notated. Details are on the page Notation symbols.

Common mistakes

• Equating the number of strokes with the scientific octave number: three strokes mean C6, not C3. In the older system the number of strokes is three less than the scientific octave number.
• Counting ledger lines wrongly: the C6 lies on the second, not the first ledger line above the staff.
• Equating the notation with the sound: notes written with 8va sound an octave higher than notated.