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Music Theory - Scales
In nature there are an infinite number of pitches to choose from, determined simply by the frequency of the waveform that is generating the note. Mankind has ever sought to simplify nature and impose patterns on its chaos and to be fair some agreed system of pitches is necessary to the development of melodic music. Most systems use the octave as the basis for ordering pitches.
An octave is a naturally occurring phenomenon whereby notes with a frequency
ratio of 2:1 appear to have the same pitch - the frequency ratio of middle
C to the next C on a keyboard is 2:1. Once the idea of a natural octave
is established a pattern of pitches can be fixed by choosing one starting
frequency and then splitting the octaves that it generates - the only question
is where to make the divisions and how often to make them. The intervals
that make up the octave characterise a particular culture of music and in
Western music the distances are commonly made up of semitones and tones.
An octave in Western music is made up of twelve semitones (the interval
between any adjacent keys on a piano is one semitone). Scales are simply
patterns that break up the distance between two notes that are an octave
C major spans an octave from C to C in seven steps or intervals based on the following pattern:
TONE TONE SEMITONE TONE TONE TONE SEMITONE
In traditional notation it looks like this:
And on a keyboard it covers the following notes:
A Brief History Of Scales
The earliest musical scales are attributed to the ancient Greeks and this is the reason for the alien sounding names that are still associated with various modes (or step-patterns). Dorian, Phrgyian, Lydian and Mixolydian were all tribes in ancient Greece. The scales were originally composed of eight notes, which ran in descending order, but when the church adopted them in the Middle Ages the order was reversed and the scales were renamed modes. Not content with changing the order the church also changed a number of other elements (such as the starting note) and arrived at seven modes, one for each of the white notes on a keyboard.
This arrangement survived until about the 16th century when the increasing complexity of polyphonic composition (containing more than one melody line) began to outgrow the modal system and by the next century a new harmonic order was being evolved. This new arrangement relied heavily on keys and tonality. The idea of a tonic or home-key was developed and the intervals of the scale were fixed by their distance from it. This allowed key signatures which identified the home-key and ordered the scale and melody in reference to it. The diatonic major and minor scales are derived from the system of keys and key signatures. The most important scales in Western music today are the diatonic major scales and the three relative minor scales.
Modality And Tonality
Mode: The step-pattern of the intervals between notes (the way that the notes are split into intervals across an octave).
Scale: A series of notes spanning an octave, formed from this step-pattern. (A number of scales can be formed from each mode.)
Tonality: The quality determined by the starting note of a scale.
The individual step-pattern of a mode gives it a characteristic sound that can be transposed to any key. The starting note determines the scale's tonality and the step-pattern of the intervals determines its modality. C major has 'C' as its tonality and a major step-pattern as its modality. Both tonality and modality are important to the sound of the scale, as the tonality will determine the harmony and the modality will determine the melodic variation.
This may sound confusing and is difficult to explain without the use of
music itself. Playing the first note of a scale will give you some idea
of the sound you can expect but until you play the intervening notes and
reach the first note again (an octave higher) you will not know what melodies
can be built with it. Play each of the scales below and you will get a clearer
idea. Both scales start and end on C (and therefore have C as their tonality)
but you will immediately hear that their different step-patterns give them
each a unique sound. The major scale is brighter and more optimistic while
the minor is somehow darker and sadder. What is true for the scale is true
for the music composed around the scale and for this reason some of the
saddest pieces of music are written in minor scales (E minor is arguably
the saddest of them all).
The same thing can be heard with the chords of each scale: