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victoria Williams Music Theory

Victoria Williams

LmusTCL BA Mus (Hons) MISM

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Next UK ABRSM Online Theory Exams Grades 1-5:
16th March 2021
Next UK Trinity Paper-based Theory Exams Grades 1-8:
Sat 8th May 2021

Grade 4 Music Theory lesson 2: Double Sharps, Double Flats & Enharmonic Equivalents

Double Sharps

The sharp symbol (#) raises the pitch of a note by a semitone (or "half step"). D# is one semitone higher than D, and F# is one semitone higher than F.

Double sharps raise the pitch of a note by two semitones (or a "whole step"), and the double sharp is printed as a sort of fancy cross, like this: double sharp

When you write them by hand, you can just write a normal cross, like an X. 

This note is G double sharp: 



Double Flats

In the same way, a double flat lowers the pitch of a note by two semitones (a whole step). There is no special symbol for a double flat, we just write two flat signs close to each other, like this: 


This note is E double flat: 



Why do we need double sharps and flats?

Double sharps are very common. We need them when we write music in some minor keys, when those keys contain a lot of sharps. You'll learn more about this in lesson three.

Double flats are much less common - they are usually used when a piece of music is modulating (in the process of changing key).


Cancelling Double Sharps and Flats

Double flats and sharps affect any subsequent notes in the same bar of the same pitch, just like single flats and sharps. But let's say you have a D double sharp followed by a D sharp. There are two ways you can notate this:

  • You can write a single sharp or flat on the D#, or 
  • you can add a natural sign before the sharp/flat on the D#

Both of these methods are acceptable:


Some people consider it to be a bit "old fashioned" or "untidy" to use the second method to cancel an accidental. You will probably see it in lots of printed music, however. 

If you need to write a natural note after a double sharp/flat, simply write the note with a single natural sign: 


You don't need to write two natural signs, one is enough (but two is also ok).


Enharmonic Equivalents

 "Enharmonic equivalent" may sound complicated, but it's actually a very simple idea.

Let's start with an easy note - F sharp. We know that F sharp is one semitone (half step) higher than F (natural). But we also know that it's one semitone lower than G natural, so we could also call the note G flat. An enharmonic equivalent is simply another way to "spell" the same note. F sharp and G flat are "enharmonic equivalents". 

Enharmonic equivalents are often used when we change key within a piece. 

Some common enharmonic equivalents are C#/Db, D#/Eb, G#/Ab and A#/Bb. These are the black notes on a piano keyboard. 

Slightly trickier, these are white notes on the piano:  E/Fb, E#/F, B/Cb and B#/C. 

All the notes with double sharps and flats also have enharmonic equivalents: C##/D, D##/E, F##/G, G##/A and A##/B, and for the flats, C/Dbb, D/Ebb, F/Gbb, G/Abb and A/Bbb.

 Remember that when you write scales, you can only use each letter name once (except for the tonic). This means that you have to be careful to choose the correct enharmonic equivalent. For example, in the scale of G# minor, the 7th degree of the scale is F##. An enharmonic equivalent of F## is G natural, but you cannot write G natural in a G# minor scale, because the letter name is already used.


In the Exam

In the grade four exam, you will be asked to name the enharmonic equivalent of one or two notes. It's usually easier to do this if you can imagine a piano keyboard. If you find it hard to imagine in your head, sketch an octave of a mini keyboard out on the scrap paper you're provided with in the exam room. 



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