Octave can have 42 evenly spaced tones {42-tone scale}.
The twelve octave semitones can have equal frequency spacing {chromatic scale}| {modern scale}. Twelve major and twelve minor chromatic keys are available. Major keys use tone-tone-semitone-tone-tone-tone-semitone. Minor keys use tone-semitone-tone-tone-semitone-tone-tone. Chromatic keys start on different semitones. All major keys sound the same, and all minor keys sound the same.
Diatonic scales {concordant scale} can have correct intervals and not use octaves. Alternatively, octaves can have unequal intervals to fit into octave, but singers altered tones to make correct intervals.
In 16th century, concordant-scale note intervals changed to fit the twelve scale tones into octave, with almost equal intervals between semitones {tempering the scale} {discordant scale} {discordance}.
Scales {ecclesiastical scale} can use fewer than five tones.
Scales {enharmonic scale} can use octave tones and quartertones.
Octaves can have five whole tones {pentatonic scale} {five-tone scale} {Greek scale}.
Octaves can have 24 quartertones {quartertone scale}.
Octaves can have six whole tones {whole-tone scale} {six-tone scale}.
Octaves can have five whole notes and two halftones {diatonic scale}|. Diatonic scales used other note spacing in 1600s but now are only major or minor scales.
Diatonic scales {major scale}| can have intervals tone-tone-semitone-tone-tone-tone-semitone and sound lighter and brighter.
Diatonic scales {minor scale}| can have intervals tone-semitone-tone-tone-semitone-tone-tone and sound heavier and darker.
Equal temperament scales have no sharps or flats {open key} {C key} {key of C}, one sharp note, one flat note, and so on.
The twelve acoustically correct diatonic-scale intervals do not make exact octaves, missing by one quartertone {Pythagorean comma}. To fit intervals into octaves, different keys {mode, Greek music} use different interval series, with different spacing between tones and semitones, so keys sound different.
Diatonic scales can start on first note {fundamental, music} {tonic, tone} {key, diatonic}.
Major diatonic scales have tone {dominant tone}| a fifth above tonic, in frequency ratio 3:2.
Major diatonic scales have tone {subdominant tone}| a fourth above tonic, in frequency ratio 4:3.
Major diatonic scales have tone {leading tone}| seventh above tonic, in frequency ratio 9:5 or 15:8.
Ancient Greece used eight different scales {mode, scale}, named after different tribes. Notes and intervals are the same for all modes, but fundamental tone and central tone differ.
Modes have associated moods {ethos, music}.
Greek modes were descending scales, so top tone was fundamental tone. Modes had central tones {nese}.
Dorian-mode nese is central tone of interval from second F below middle C to F above middle C {greater perfect system}.
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Date Modified: 2022.0225