Key Signatures

What is a key signature, and what does it mean?

Key Signatures are found at the beginning of music (standard notation) to conveniently describe how to read the notes played, and to clear up the staff from unneccessary accidentals.

They key signature tells you that unless told otherwise, always apply the following accidentals to the notes that follow.

Key of G - 1 sharp
All F's will be sharped throughout unless otherwise noted.

|                        |
|    4                   | 
|    4        O          |
|                O       |

The key signature is written after the clef, and before the key signature.

Although it is convenient to write a key signature to represent the notes that are constantly affected by accidentals, there are only a limited number of key signatures. These limited number correspond to keys which coorespond to THE major scale (and the minor scale for minor keys).

A review of accidentals.
Recall, the following accidentals have the following effects on pitch.
# sharp - raises the pitch/tone by a half-tone (half-step)
b flat - lowers the pitch/tone by a half-tone (half-step)
natural - cancels any and all accidentals (including in the key signature)
x double sharp - raises the pitch/tone by a whole-tone (whole-step)
bb double flat - lowers the pitch/tone by a whole-tone (whole-step)

- In order to notate the proper pitch, place the accidental directly in front of the pitch to be effected.
- The accidental supercedes any previous accidentals.
- The affect continues throughout the entire measure or all octaves of the pitch, unless contraindicated by another accidental.
- An accidental in the key signature lasts throughout the music, unless an accidental is used in a measure or the key signature changes.
- Key signatures have either sharps or flats or neither (key signatures do not contain mixtures of sharps and flats).

The Sharps or flats written in a key signature always appear in a specific order.
That order is as follows:
for sharps:
and for flats:
B,E,A,D,G,C,F (the reverse)

for example,
the key with 3 sharps would have F#,C#, and G# in the key signature in that order.

|              |
|      #       |
|              |
|              |

The key signatures corresponding to the key, is associated with the major scale or the minor scale (see 3 previous lessons).

The major and minor keys arranged by increasing numbers of sharps or flats are the following:

Key of C (Key of Am) = no sharps or flats
Key of G (Key of Em) = 1 sharp, F#
Key of D (Key of Bm) = 2 sharps, F#,C#
Key of A (Key of F#m) = 3 sharps, F#,C#,G#
Key of E (Key of C#m) = 4 sharps, F#,C#,G#,D#
Key of B (Key of G#m) = 5 sharps, F#,C#,G#,D#,A#
Key of F# (Key of D#m) = 6 sharps, F#,C#,G#,D#,A#,E#
Key of F (Key of Dm) = 1 flat, Bb
Key of Bb (Key of Gm) = 2 flats, Bb,Eb
Key of Eb (Key of Cm) = 3 flats, Bb,Eb,Ab
Key of Ab (Key of Fm) = 4 flats, Bb,Eb,Ab,Db
Key of Db (Key of Bbm) = 5 flats, Bb,Eb,Ab,Db,Gb
Key of Gb (Key of Ebm) = 6 flats, Bb,Eb,Ab,Db,Gb,Cb

Easy recognition of keys/which key is it?
no sharps or flats = Key of C
1 sharp = key of G (F#)
1 flat = key of F
all sharp keys - the last written sharp is the 7. go up to the next adjacent line or space for the name of the key, see G above.

all flat keys (except F), 2nd to last flat is the name of key (key of Bb has 2 flats, Bb and Eb, Bb is the 2nd to last flat = name of key).

We can display the keys in order in a circle. This is often referred to as the circle of 5ths. Going in one direction has the tonic rising by a 5th, in the other direction a 4th.

                F           G                       
            Bb   Dm       Em     D                
              Gm              Bm                
        Eb  Cm                 F#m  A               
              Fm            C#m                                          
           Ab    Bbm      G#m    E                  
               Db           B                                                                Gb/F#                             

How do you write a change of keys?
first write a measure with "naturals" cancelling to previous key, then write in the new key in the next measure.

ex. going from key of D to key of F

|         ||       |
|    nat. ||       |
|         ||       |
|         ||       |
(difficult to show due to text only)

For those familiar with modes, it is better to use the key signature that already has the same tones as the mode than to constantly place accidentals on the staff.

for G-mixolydian, use key of C, not the key of G to notate.

Next lesson is on triads.

Christopher Roberts

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Next lesson - Triads
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Last updated May 1, 2003
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