4 Understanding Key Signatures 4.1 Introduction Perhaps the easiest starting point for understanding key signatures is to look at the layout of the piano keyboard. This layout was not invented at a stroke, of course, but evolved through pre-tonal times when modes served the purposes which, today, are fulfilled by a wide range of scales. Early keyboards consisted only of the equivalent of the white keys on today’s instruments, and consequently, it is possible to reproduce the modes on the modern keyboard.
C♯
D♯
D♭
C
F♯
E♭
D
G♯
G♭
E
F
A♯
A♭
G
B♭
A
B
C
This present arrangement of black and white keys [as illustrated above] has been in existence since about the mid-15th century and represents a compromise between likely hand spans, the width of individual keys, and the assimilation of pitches to create 12 intervals. And so, between middle C, say, and the C one octave higher, there are 12 intervals called semitones, as follows: C to C ♯ / D ♭ C ♯ / D ♭ to D
D to D ♯ / E ♭
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