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Key Signatures and Accidentals


Question: I am currently working on naming the keys of melodies with accidentals, then re-writing them with key signatures. How can I go about doing this? I have forgotten the steps my teacher taught me last week so some help would be very much appreciated. :)

– Selina (Langley, British Columbia, Canada)

Albert’s reply: Rewriting melodies containing accidentals is a valuable exercise for learning all the keys and reinforcing your knowledge. The process is quite simple. The first step is to recognize the key of the melody. The key of a melody, piece or section thereof has two components: the tonic and the mode.

Find the Tonic

You can almost always infer the key of the melody from the music. The reason is that the tonic is the “center of gravity” of music. The tonic is the first note in a major or minor scale. It is the main note of a piece of music. If your piece is in C major (or C minor), then C is the tonic. If you piece is in B-flat major (or B-flat minor), then B-flat is the tonic.

Determine the Mode

Is the melody in the major or minor mode? The lesson on major and minor keys will show you how to determine the mode of your melody, and the ones on how to tell the key of a piece of music and distinguishing minor from major go into more detail.

Sidebar: Modulation and Modes

The key changes during all but the simplest pieces of music. Thus, a piece in C major will often modulate to the closely related keys of G major (the dominant), F major (the subdominant) or A minor (the relative minor). A melody or passage you wish to notate with the key signature may very well contradict the key of the piece as a whole.

Moreover, not all pieces of tonal music are in major or minor! It so happens that most music in our culture, from the Renaissance through to the latest Top 40 hits, are in either the major or minor mode, but this need not be the case. The lesson on music modes explains all seven modes in detail, with audible examples. (You’ll even learn how the piano keyboard got black keys, which has to do with the modes!).

Get the Key Signature

Once you know the tonic and the mode (major or minor) – remember that tonic plus mode equals key – you just need to write the key signature. You should know all the key signatures, but if you don’t you can construct the key signature quite easily, just by using the tonic, the mode (major or minor) and the pattern of half and whole steps, explained in the lesson on how to play a piano scale.

Order of Sharps and Flats

Sharps and flats in key signatures proceed in order of fifths. Remember that sharps go up, and flats go down. The first sharp is F-sharp. A fifth above F-sharp is C-sharp – just count F G A B C and you’ll arrive at C-sharp. A fifth above C-sharp is G-sharp – count the five notes C D E F G and you’ll arrive at G-sharp. The remaining sharps are D-sharp, A-sharp, E-sharp and B-sharp.

You can see them all in the key signature for C-sharp major and A-sharp minor:

Flats, on the other hand, go down. The first flat is B-flat. Going down a fifth – B A G F E – we arrive at E-flat. Down a fifth from there – E D C B A – we land on A-flat, which is the third flat in our series. Continuing a fifth downward for each flat, the remaining flats are D-flat, G-flat, C-flat and F-flat. All flats can be seen in the key signature for C-flat major / A-flat minor:

Rewrite the Music

Finally, all you need to do is rewrite the music! Let’s take “Mary Had a Little Lamb” as an example:

By following the above steps, we discover that the tonic is A-flat and this song is in major; it is thus in A-flat major.

Adding the key signature for A-flat major with its four flats, we get:

Remember that a piece of music may have sharps, flats or naturals foreign to the key signature. In fact, any time you see an accidental (a sharp, flat or natural sign) that is not in the key signature, that note is a non-scalar tone, meaning simply that it’s not in the scale.

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