Editing Octave (section)

== Music theory ==
Most [[scale (music)|musical scale]]s are written so that they begin and end on notes that are an octave apart. For example, the C major scale is typically written {{nowrap|C D E F G A B C}} (shown below), the initial and final Cs being an octave apart.

{{block indent|<score sound="1">  {

\override Score.TimeSignature #'stencil = ##f
\relative c' {
  \clef treble \key c \major \time 8/4 
  \once \override NoteHead.color = #red c4 d e f g a b \once \override NoteHead.color = #red c
} }
</score>}}
Because of octave equivalence, notes in a chord that are one or more octaves apart are said to be ''[[Voicing (music)#Doubling|doubled]]'' (even if there are ''more'' than two notes in different octaves) in the chord. The word is also used to describe melodies played in [[Contrapuntal motion#Parallel motion|parallel]] one or more octaves apart (see example under Equivalence, below).

While octaves commonly refer to the perfect octave (P8), the interval of an octave in music theory encompasses chromatic alterations within the pitch class, meaning that G{{music|natural}} to G{{music|sharp}} (13 semitones higher) is an [[Augmented octave]] (A8), and G{{music|natural}} to G{{music|flat}} (11 semitones higher) is a [[diminished octave]] (d8). The use of such intervals is rare, as there is frequently a preferable [[enharmonic]]ally-equivalent notation available ([[minor ninth]] and [[major seventh]] respectively), but these categories of octaves must be acknowledged in any full understanding of the role and meaning of octaves more generally in music.