Tonality - An Important Concept In Music
If you attend orchestral concerts or read the liner notes to classical CDs, you will probably notice that symphonies or concertos etc, are described as being"in the key of C major, or C minor, D major, D minor etc." Just what does this mean ?
Basically, in western music at least, there are exactly twelve notes from C to C. C, C sharp or D flat, the same pitches, D, D sharp or E flat , E, E sharp, the same pitch as F, F sharp, the same as G flat, G, G sharp, or A flat, A, A sharp or B flat, B , B sharp , the same as C.
Of course, there are pitches between these 12 notes, but they are not commonly used . Of course, they are not uncommon in the musics of exotic lands. A pitch halfway between C and C sharp is called a quarter tone, and even smaller intervals are possible.
But basically, any piece of music, classical or otherwise, you are familiar with, uses one of the 12 tones between C and C as its home pitch. Any melody or piece of music will tend to be in a key, and use any one of the 12 tones as the home note. And that melody, if it starts on the note C, can be transposed to any of the other 11 pitches.
In western music, we have the system of major and minor keys, C major, C minor and so forth, coming from a different arrangement of the intervals between the notes. C major uses simply the notes C,D, E, F, G, E B, C. The minor kery uses a different arrangement, or arrangement of the notes. C, D, E flat, F, G, etc. The minor keys introduce what are called Chromatic notes of the scale, that is E flat, A flat, etc. The diatonic cotes are C,D,E, F, G, A ,G, and the chromatic tones are C sharp, or D flat, E flat or D sharp, F sharp or G flat, G sharp or A flat, B flat or a sharp.
The term chromatic come from Greek Chromos and means "color" as in Chromosomes, because it's said that these notes add"color" to the music, that is making it less bland the just the diatonic scale. So we have a system of major and minor keys based on any of the notes of the scale.
Johan Sebastian Bach wrote a famous series of preludes and fugues in all the major and minor keys called "The Well-Tempered Clavier", which can be played either on harpsichord or modern piano . Chords can be built on any of these tones, for example, C, E and G, making your basic C major chord with which any work in C major will begin and end with. The minor chord uses C, E flat, and G , which will typically be used to begin and end a piece in C minor.
The note C is the the home note, the most important tone in the key of C major. Of course, in just about any piece of classical music, symphony, concerto or whatever, there will be key changes, or the piece will sound awfully monoitonous. These key changes are known as Modulations .. But the piece will always return to the home key. Theoreticaslly, a piece can modultate to any other key. But you always return to the home pitches of C,E, and G. It's rather like gravity.
Certain keys are closer to the home key than others ; G major is much closer than F sharp major, for example. In the time of Mozart and Haydn, the harmonies were simpler than later eras, and the more distant keys rarely used. In a symphony or concerto, a C major opening will usually first go to G major, the nearest key.
But starting in the later 19th century , composers became much more adventurous, modulating to distant keys quickly and using much more complex chromatic harmonies, such as Franz Liszt and his son-in -law Richard Wagner. This complex chromaticism led to a kind of weakening of the music seeming to be in a key at all, and eventually led to what we call Atonality, or the absence of any sense of key at all, which began in the early 20th centuries with composers such as Arnold Schoenberg and others.
The famous prelude to the great opera "Tristan and Isolde " by Wagner, written as early as the 1850s illustrates this weakening of tonality. It's difficult to get your bearings in this piece, the sense of tonality is extremely ambiguous. Later, French composers such as Claude Debussy experimented with writing tonally ambiguous music, but the music still ended in a key eventually. But Schoenberg and his assocates broke free of tonality altogether. However, many 20th century composers never adapted atonality, even though they used very complex harmonies.
However, most of the music people hear every day, whether classical or popular, relies on the concept of tonality just as the earth relies on gravity.