Saturday, 5 January 2013

Music by Numbers

One of the standard myths about composition is that a composer or song writer just hears a tune in his head then writes it down. You get the idea Mozart playing billiards whilst composing tunes in his head, Schubert walks by a brook and gets the idea for his Schone Mullerin, Beethoven walking in the country, sketch book in hand listening to bird song and writes down instantaneously his Pastoral symphony and so forth. Thus the ability to compose music is seen as an inuitive affair only given to specially gifted people who are seen as creative genius's whilst mere mortals can only gasp in awe and wonder.

It may surprise some people that quite often music is constructed to conform to a pattern or to use a modern term algortihm. One of the simplest algorithms or forms is the 4 bar phrase. It only requires three chords in any major scale to write a tune. A triad is formed from three notes on the scale each a third above each other the three main triads are formed from the first degree of the scale, the fourth degree of the scale and the fifth degree of the scale. Thus the primary triads are

                                     I    -   1 3 5
                                     IV -  4 6 1
                                     V  -  5 7 2

and for C major I would be CEG, IV would be FAC  V would be GBD  To harmonise these chords notes on the strong beat of a melody must usually be taken from notes of the chord and generally speaking each bar normally is based around the notes of a chord. For a four bar phrase the pattern is usually I-IV-V-I

If one uses chords in root position then the bass line per bar is already written for you it is simply

  1 4 5 1 and normallly the base line starts with a descent

Thus for C major the bass line would be C F G C. The melody would normally start on the first note of the scale so that must be C or 1 one or two octaves above. generall two. The melody normally moves in the opposite direction to the bass line so for our melody we must have a general  upward ascent to the  4th or 6th  and then continue  degree of the scale to fit in with the notes needed to match the notes of the IVth triad in the first bar a downward descent to the 5th Degree of the scale in the third bar and a continuation downward to the first degree. So the basic shape of the melody is 1-4(or 6) then there must a descent to 2  and then finally 1 . Quite often the penultimate note in the melody is 2 which nicely leads to the first degree. So that is the recipe for the melody. In C major start on  C ascend to  F in the second bar,throw in some A's  in the third bar make a descent from either F or A to D and end on C in the last bar.  This pattern will work for all 12 major keys. So there you are 12 tunes for the price of 1

Then the other two parts are more or less dictated by the need to avoid consecutive 5ths or Octaves by which is meant that between any two chords in each part there must not be intervals of 5th or Octave between them. This is quite tricky to achieve but a bit of patience normally gets there. One trick is to alternate triads in closed position with triads in open position and also make sure that the inner parts move to the nearest note.

A basic pattern for the chords which avoids parallel fifths would be
    S    1   4   2  1
    A   5    6  7  5
    T    3   2  2  3
    B    1   4  5  1

Note that although the Bass and the soprano move from the first degree of the scale to the 4th degree this does not count as a parallel octave as the octave is approached by contrary motion.

So there you have it how to write music by numbers. This basic formula forms the basis of most pop music or hymn tunes. What makes the variety is of course  the use of different rhythmic devices or say arpeggios of the chords. So that instead of a block chord in the bass line you would have C E G ascending.

Needless to say as more and more harmonies are introduced the music becomes much more sophisticated and classical music is usually more complicated than the basic I-IV-V-I formula one of the reasons why I feel that it is not elitist to acknowledge the superiority of classical music over most pop music certainly the stuff that seems to form the basis of the X factor and other such commercial pap.

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