Key Signatures

In the last chapter, we found that by adding sharps or flats to various scale degrees, we could form a major or minor scale beginning on any pitch class. Since these accidentals are used consistantly within each scale, we can use a key signature to indicate them. A key signature is a standardized collection of all the sharps or flats used in a scale, occuring at the beginning of each staff. For example, instead of adding a flat to each of the notes of a melody built on a D-flat major scale, we can use a key signature to indicate them. The accidentals used in the key signature apply to all of that pitch class throughout the music -- for example, a B-flat in the key signature means that all B's , in all octaves, are now lowered to B-flat without having to add an accidental. (See the figure below)

In key signatures, the sharps and flats are arranged in a specific order and position. As the following chart shows, the first sharp is always F-sharp, and is always located in the same position. This is the same for all of the keys: each key adds another sharp or flat. It is important to memorize the order and arrangement of sharps and flats for all keys. This is part of our basic musical language. Just as the order of letters within a word is important, ("teh" and "the" are not the same) the order of the sharps and flats is also important. We usually group both the major and minor keys together, so that one sharp is the key signature for both G Major and e minor. This related minor key (related via the same key signature) is called the relative minor.

Notice that as you add sharps, each new key's tonic is the same as the fifth scale degree of the previous key. As you remove flats, the new key's tonic is the same as the fifth scale degree of the previous key. Another interesting point to note is that at the point of six flats and six sharps, the keys are G-flat and F-sharp Major (and e-flat and d-sharp minor) - which are enharmonically equivalent. This has the result of forming a kind of loop, or cirle around which the keys progress in fifths. This can be summarized by the following chart, showing a simple presentation of the relationships between all major and minor keys called the circle of fifths:

If we move clockwise, each new key is build on the fifth scale degree of the previous key. Every musician should have all of the key signatures for all keys (major and minor) memorized! Being able to "figure it out with enough time" is like having to spell each word outloud before you can read it: it's a starting point, but it's not "reading music".

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