There are fifteen keys used in western, tonal music. These include seven sharp keys, seven flat keys, and one key without sharps or flats. Each key signature can be used to signify a major or a minor key depending on context. For example, if you see one sharp in the key signature, the music is either in the key of G major or E minor. You would need to look at the music itself—i.e., the harmonic structure—to determine whether or not the music is in a major or minor key.
What are flats and sharps? A flat lowers the pitch of a note by a half step, and a sharp raises it by a half step. Flats and sharps are written on the staff in a specific order. Key signatures contain either flats or sharps—not both. For example, you will never see a key with two flats and one sharp. In a key signature, the set of sharps or flats is written after the clef but before the time signature.
All notes written within the body of a piece must defer to the key signature. For instance, the key of G major contains an F#. This means that all F's found in the composition will be played as F#. In this context, if the composer wants the performer to play an F, a natural sign will be written to the left of the note. In this example, the F natural would be called an accidental.
FIGURE 5-4: Flat, sharp, and natural sign
An accidental refers to any note—sharp, flat, or natural—that is not included in the key signature. Figure 5-4 shows what a flat, a sharp, and a natural sign look like.
To some listeners, each key bears a specific musical “color” or “personality.” Because of this, composers and songwriters alike sometimes have favorite keys. Key signatures have practical value too. They are used to avoid writing lots of sharps or flats in the body of the music. Lots of sharps and flats can make a piece look messy. In turn, this makes it harder for musicians to play the music.
Ultimately, a key signature identifies a piece of music's home base. By its very nature, tonal music contains resolution points or musical periods. Also, a composition's conclusion usually matches the key. For example, if you're in the key of C major, the piece will likely end on a C major chord. Further, key signatures define the primary scale or mode of a piece. In turn, this scale defines the specific chord names (not types) used. As music gets more and more complex, exceptions to all of this may occur.
As previously mentioned, each key signature denotes two keys: a major key and a relative minor key. The relative minor key uses the same set of pitches as its major counterpart. The minor key is defined by three scales that begin and end a minor third below (or a major sixth above) the relative major. An example of this would be the relationship between “C” and “A.” “A” is located a minor third below “C” and a major sixth above “C.” The relative minor key also uses its own set of cadences (see Chapter 6).
In order to identify sharp keys, look at the last sharp then raise the pitch one half step. For example, the key of A major has three sharps (F#, C#, and G#). One half step above G# is A.
In order to identify flat keys, look at the second to last flat. This flat identifies the key. For example, the key of A. You will need to memorize the major and minor key signatures with one flat. They are F major and D minor, respectively.
C major and A minor use all naturals (no sharps of flats) in their key signatures. However, as you will learn later on, the A harmonic minor scale and the A melodic minor scale both contain accidentals.
In each key, sharps and flats appear in a fixed order and position on the staff. You cannot alter this when writing out a key signature. There are a number of mnemonic devises used by students to remember the order of the sharps and flats on the staff. One memory tool for remembering sharps is: Fat Cows Get Dizzy After Eating Barley (F, C, G, D, A, E, B). A memory device for remembering the order of flats is: BEAD Go Call Fred (B, E, A, D, G, C, D). Feel free to make up your own mnemonics too!