I've been playing piano by ear for a long time and now I am trying to learn the first movement of the Moonlight Sonata. I am a little confused about the meaning of a little cross placed right before a note.

It seems to cancel a sharp or something, but the meaning is not quite clear! If you understand the symbol I'm describing help me out here!


I'm assuming that you're talking about the one that looks like a blocky X.....this is a double sharp. Instead of shifting the tone up one half step, it shifts the tone up 2 half steps (i.e. 1 whole step).

enter image description here

This image shows G double-sharp in the treble clef, and E double-flat in the bass clef. G double sharp is enharmonic with A natural, and E double-flat is enharmonic with D natural.

Coincidentally, Moonlight Sonata is the piece where I first encountered double-sharps, too!

  • I think what brought confusion while I read was that at some point I think there was a double sharp on a note which was already "sharpened" in the scale, is it possible that in this case it only "raises half a tone"? If you understand what I mean. Mar 25 '12 at 3:59
  • 10
    Yes; this overrides any other accidentals in the key signature. Think of it as sharping a sharp, if it helps. For a more thorough discussion than I can provide, you should look at this question. music.stackexchange.com/questions/87/…
    – Babu
    Mar 25 '12 at 14:55
  • @PatrickDaSilva: Like you noticed, it really raises it half a note from the already sharpened note in the key signature. This is the most common situation to use the double-sharp. I have never seen it used to raise a note a whole step that is not already raised by a normal sharp. See the linked question in Babu's comment for more details on why it is used.
    – awe
    Mar 30 '12 at 11:03
  • @PatrickDaSilva All accidentals "cancel" whatever was in place before; adding a sharp to a note that's already sharped in the key signature is equivalent to "reminding" the player that this note should be sharp, not adding an additional sharp. Similarly, adding a flat would lower it two half-steps from the "sharp" version of the note, not bring it back to a natural. Jun 1 '13 at 21:12
  • 2
    Probably the most commonly encountered double-sharp is Fx in a piece in c#-minor, so I'm not surprised you both encountered it for the first time in what is probably the most famous c#-minor piece. This is because modulating to the dominant key is so common, and the key of G# needs a leading tone. Bach invented the symbol for one of the C# pieces in the Well-Tempered Clavier. Jun 20 '14 at 23:15

Babu's answer contains the canonical answer, it is a double sharp used to sharpen a note that has already had a sharp applied.

I can see how it is hard to find these things, when we see the symbol on the page what on earth would we type into a search engine? This is where visual lists of musical symbols come in useful. Wikipedia provides one such list of musical symbols which we can visually scan to find the symbol we are looking for. Yours is about halfway down the list:

Wikipedia screenshot

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