The Double Sharp Sign - Double Flats Sign - Double Accidentals

Have you ever enocountered these musical signs?

The double flat

The first sign is a double flat. It lowers the pitch of a note by two semitones. In the example above, the double flat lowers the D note by two semitones (a whole tone), so the actual note is C. The double flat doesn't have any special sign. You will just see two flats: on the left side of the note.

The double sharp

The second sign is the double sharp. It raises the pitch of a note by two semitones. In example 2, the double sharp raises the F note by two semitones (a whole tone), so the actual note is G. The double sharp has a special sign: which is placed on the left side of the note.
If the notes are marked with their names (A B C etc.), you may see ## instead of the special sign, for example: F##.

Why do we need the double sharp and flat signs?

Isn't it more clear and simple to write G instead of F##?

This way of writing looks clumsy and unnecessary, but there is pure logic behind it.

Let's take the scale G major:

There are 7 different notes in this scale:
G A B C D E F# (I didn't count the last note because it is like the first one- G).
When a composition is written in this scale, more likely F# will be seen, and not Gb, although these two notes actually have the same pitch.

Here is the most famous piece in G major scale:

Minuet in G by Bach:

Q: Why didn't Bach write Gb?
A: The piece is written in G major scale, so the notes that are being used are:
G A B C D E F#
If Bach had written Gb, then the scale would have been:
G A B C D E Gb
It is unusual to use the same name for 2 different notes (G and Gb) We think of a scale in melodic steps so the next natural melodic step after E would be F (in our case F# since we have to climb a whole tone in the scale!

Why do we sometimes see E#, instead of an F?

Let's take a scale with a lot of sharps: F# major.

Q: Which are the 7 different keys of this scale?
A: F# G# A# B C# D# E#

Q: Why do we see here E#, and not simply an F?
A: The scale contains 7 different notes, so if we used an F instead of E#, the scale would have been:
F# G# A# B C# D# F
It is unusual to use the same name for 2 different notes (F and F#)
By missing the E# by naming it F instead we would miss the whole idea of having a scale which moves in melodic steps again. (from D to E).
Instead we would get the idea that we performed a wide jump from D# to F which is the jump of TWO STEPS!

I hope you have understood the logic so far. If not, please read it carefully again because the next explanation is based on the logic above.

Now, for the question:
" Why do need a double sharp?"

Let's now take the scale G# major:

Q: Which are the 7 different keys of this scale?
A: G# A# B# C# D# E# F##

Although it is simpler to write G instead of F##, the professional composer will use the double sharp.
The reason for using the double sharp derives from the same logic as before; If the composer uses G instead of F##, then the scale will be: G# A# B# C# D# E# G .
I'd like to remind you that it is unusual to use the same name for 2 different notes (G and G#).

Using the correct accidentals

I would like now to expand a little bit the significance of using the correct accidentals.

Most of the music we know is built of scales. In each moment of the piece the professional composer writes the correct accidentals so the player will know in which scale he is. The professional composer prefers to use the correct accidentals even if he has to use the double accidentals (the double sharps or the double flats).

Why is it so important to indicate the right scale?

Well, first of all it is a tradition of hundreds of years.
Secondly, it helps to understand the music better. When a player knows in which scale he is, he will better understand the direction, the harmony, and the melody of the music etc. Thus he will play better.

By the way:
In bowed instruments such as violin, cello etc., it is even more important to write the correct accidentals.
Why?
You will be surprised to know that in these instruments E# and F do not sound the same!!!
The same happens with B# and C, or F## and G, etc. The violin player actually plays B# and C differently!

Watch some of the scales, majors and minors, and you will the use of double accidents.

Double accidentals in chords

I have written this section after we received these questions:

Q: Why does an A augmented chord contain an E# instead of F? Why does a B augmented chord contain an F## instead of G? Why does a C# augmented chord contain an E# instead of F?

A: The names of the chord notes consist of alternate notes from the music scale.
Let's take the scale:
A B C D E F G

A chords: A→ C→ E
B chords: B→ D→ F
C chords: C→ E→ G
D chords: D→ F→ A
E chords: E→ G→ B
F chords: F→ A→ C
G chords: G→ B→ D

Let's take some examples of the A chord. The three components of this chord are: A C and E.
Am includes these notes: A C E
A includes these notes: A C# (not Db) E.
A diminished includes these notes: A C Eb (not D#)
A augmented includes these notes: A C# and... E# (not F!).

Let's take now some examples of the B chord.
The three components of these chords are: B D and F:
Bm includes: B D and F# (not Gb)
B includes: B D# (not Eb) and F# (not Gb)
B diminished includes: B D F
B augmented includes: B D# and...F## (not G!!)

This is the common way to write this chord down, although sometimes it looks clumsy.

Watch the augmented chords , and the diminished cords, and you will find some chords with double sharps or double flats.

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