The double sharp

Sometimes a note has to go up two semitones instead of one. That is what the double sharp is for, written 𝄪 and read "double sharp". F𝄪 is two semitones above F: the same key as G.

If it sounds like G, why not write G? Because the letter matters as much as the sound. In a piece in G sharp minor the leading note is F𝄪: writing G would break the scale, which needs an F of some kind. Spelling follows the harmony, not the keyboard.

• 𝄪 raises two semitones from the natural note, not from the already sharpened one.
• Like any accidental, it lasts until the bar line.
• The double flat 𝄫 does the opposite, and comes in the next lesson.

It is a rare sign, which is exactly why it is worth recognising at a glance: when it turns up, it is usually at the most expressive moment of the passage.