Octave key

The octave key is a key on a saxophone or oboe which raises the pitch of all notes by an octave when pressed.

axophone

On a saxophone, the octave key is positioned next to the left-hand thumb rest. Pressing the octave key opens the top tone hole in the neck of the saxophone. Alternatively, whenever the G key is fingered, the top tone hole closes and a small tone hole is opened near the top of the body.

Oboe

The modern oboe has two octave keys, sometimes three, often interconnected, the one for E5 to G#5 near the left thumb, and the one for A5 to C6 to the right of and above the front keys, depressed by the edge of the left index finger. Oboes are now available with automatic octaves. This involves extra keywork that frees the player from having to bother with an octave key at all. The bassoon has similar keys used by the left thumb, but these are usually only depressed at the attack of notes, or "flicked". The presence of this key is one of the main features which makes the saxophone easier to play than the clarinet, because the same fingerings can be used for two different octaves. The analogous key on the clarinet, the register key raises the pitch by an interval of a twelfth (19 semitones), making the fingerings different for low notes and high notes that are an octave apart.