Music Theory - Key Signatures
In our last seminar for principles of audio we covered key signatures, which included the differences between major / minor scales and how to convert between, as well as why the tonal harmonies occur in scales due to the intervals within them.
Within an octave there are twelve keys, these are known in music theory notation as A-G, with sharps and flats to cover what’re detonated as the black keys on a keyboard. There are seven natural notes and five sharps (or flats) which are each individually separated by a semitone from the neighbouring notes, and a whole tone when separated by a two semitone gap (C-D : whole tone, C#-D : semitone). These twelve keys are then (in typical western music) used in a group of seven to create a scale which then repeat up and down the octaves. This function of taking seven from twelve gives a vast combination of potential notes to be played together, in total there are 462 possible combinations![fromthewoodshed.com]
These are differentiated with different names, the two of which we covered are the major and minor which both accordingly sound either happy or sad. The major scales are constructed by taking a root note and in sequence adding the next note dictated by the following intervals (Tone/semitone) - TTsTTTs. This will give us a major scale, such as E, F#, G#, A, B, C#, D# ( E Major), or Bb, C, D, Eb, F, G, A (Bb Major). These have a much more upbeat and happier spirited sound, in comparison to minor scales which unlike the major can come in a few different forms : melodic minor, harmonic minor, natural minor. To change a major scale into a natural minor you simply descend down three semitones to find the relative minor’s root note, to find the harmonic minor from the major you flatten the 3rd and 6th relative to the major notes as well as sharpening the 7th (if you like) to gain a leading note and distinguish it further from the major. Finally there is the melodic minor which flattens the 3rd on ascent and flattens the 6th/7th also on the descent.
From the root note in any scales the 5th is regarded as the dominant note, as it is a crucial aspect to the harmonic structure of a scale.
In the attached session file for Ableton, you can hear an example of two versions of the same short composition which have been separated into major (yellow) and minor (blue), which gives a good idea of the difference in harmonic content of the major and minor key signatures.
