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A little music theory (mostly notation, names, …and temperament)
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Physical: It has nothing to do with human beings. Ex: beating Psychophysical, psychological: human anatomy. Ex: fundamental tracking Cultural: society dependent. Ex: appreciation of Beattles songs Nature or nurture
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Doubling the frequency feels like the same pitch (pitch periodicity) f and its harmonics: f, 2f, 3f, 4f, … 2f and its harmonics: 2f, 4f, 6f, … This is not a cultural phenomena, it seems to be present in any musical culture.
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In Western music the pitch range from f to 2f is split in 12 steps (entirely cultural) f f0f0f0f0 2 f 0 C, C#/Db, D, D#/Eb, E, E#, Fb, F, F#/Gb, G, G#/Ab, A, A#/Bb, B or do, do#/re b, re, re#/mi b, mi, mi#/fa b, fa, fa#, sol, sol#/la b, la, la#/sib, si
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CEDFGAB C#D#F#G#A# C... C2C2C2C2 C3C3C3C3 C4C4C4C4
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This has changed historically but now it’s standard to take: A 4 = 440 Hz So A 5 = 880 Hz, A 3 = 220 Hz, … For the intermediate notes the whole thing is more contentious (we’ll discuss temperament later)
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higher
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What about the #’s and b’s ? C# Ab
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What about the duration of notes ? halfhalf
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Measure time in beats four beats in a measure this will count as one beat
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slightly more complex
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several instruments
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Consonance and dissonance [Let us play some intervals and find what makes them consonant or dissonant]
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C C# D D# E F F# G G# A A# B C minor 2 nd major 2 nd minor 3 rd major 3 rd 4 th tritone tritone 5 th minor 6 th major 6 th minor 7 th major 7 th
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ratio of frequencies = ratio of small integers consonance Examples: 1/1 unison 2/1 octave = 7 tones 3/2 fifth = 3 ½ tones (actually 1.4983) 4/3 fourth = 2 ½ tones (actually 1.22482) 5/4 major third = 2 tones (actually 1.25991)
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Consonance/dissonance and the overtone series unison = 0 tones
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octave = 7 tones
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fifth = 3 ½ tones
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fourth = 2 ½ tones
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major third = 2 tones
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consonance beating roughness consonance roughness …
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Temperament Problem: choose the frequencies of the notes (C, C#, D, …) in order to make the consonances very good consonances
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Remember: the best consonances are Octaves: 2/1 6 tones = 12 semitones Fifths: 3/2 3 ½ tones = 7 semitones Fourths: 4/3 2 ½ tones = 5 semitones Major thirds: 5/4 2 tones = 4 semitones …
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C C# D D# E F F# G G# A A# B C It is impossible to assign frequencies to the notes In such a way as to keep all fifths = 3/2, fourths = 4/3, … exact
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C G D A E B F# C# G# D# A# F C not the same
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Pythagorean solution Make the octaves and fifths perfect C D E F G A B C 1 9/8 81/64 4/3 3/2 27/16 243/128 2
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C D E F G A B C 1 9/8 81/64 4/3 3/2 27/16 243/128 2 one tone = 9/8 ½ tone = 256/243 1 tone = (256/243) 2 = 1.1098… 1 tone = 9/8 = 1.125 Pythagorean comma
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close, but not the same ! 1.58 1.60
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Perfect third : f 2 /f 1 = 5/4=1.25 Perfect third : f 2 /f 1 = 81/64 = 1.265… Can you hear the bad Pythagorean thirds ?
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In the Pythagorean temperament some keys are better than others Samuel Barber's Adagio for Strings CAb courtesy of G. Moore
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Other temperaments Pythagorean: good fifth (except one), bad thirds Just: some thirds and fifths are good (tonic, dominant and subdominant of some keys) Meantone: better thirds than fifths... Equal temperament: split the difference equally among notes. Nothing is perfect, nothing is too bad
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Recap of Music Theory same interval = same ratio of frequencies C 3 C 4 C 3 C 4 half tone tone
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Consonances: sensation of calm and repose Frequency ratios name 2/1 octave 2/1 octave 3/2 fifth 3/2 fifth 4/3 forth 4/3 forth 5/4 major third 5/4 major third Dissonances: sensation of tension Frequency ratios name 729/512 tritone 729/512 tritone 243/128 minor second 243/128 minor second
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Temperament: an assignment of frequencies to all twelve notes from C to B It is impossible to find a temperament where all the octaves and fifths are perfect Pythagorean: all octaves and all but one fifth are perfect. One fifth is very off (pythagorean comma). Well or equal : split the differences equally. Every semitone = 1.059…
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Equal temperament C C# D D# E F F# G G# A A# B C r r2r2r2r2 r 12 =2
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Nothing too good, nothing too bad … Fifths: r 7 = 1.498 instead of 3/2=1.5 Fourths: r 5 = 1.3348 instead of 4/3=1.3333 Thirds: r3=1.25992 instead of 5/4=1.25 …
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