From 2f38f346139afca194c1be17f6285f4d47dbe50c Mon Sep 17 00:00:00 2001
From: julian laplace
With the root, fifth, fourth, and octave in the top-left corner, the
- Lambdoma shows how the 3:2 proportion is essential to human
- perception.
+ Lambdoma shows how the 3:2 proportion is basic to musical perception.
- Mapping colors logarithmically to this wheel of fractions between 1
- and 2, with red at the octave (1:1), it naturally follows that the
- fourth (4:3) is green, and the fifth (3:2) is blue. These ratios seem
- to correspond to the photoreceptors in the human retina, which are
- sensitive to wavelengths of light in three different ranges: long,
- medium, and short. These ranges are perceived as "red, green, and
- blue" in the brain, yet our mind's eye sees a continuous cycle of
- color that loops back on itself.
-
- The musical circle of fifths, derived from repeatedly stacking the 3:2
+ The musical Circle of Fifths, derived from repeatedly stacking the 3:2
proportion, can be studied in more detail in this program's
Pythagorean scale mode, where each ratio is a
power of 2 or 3. Similar notes can be found by color and compared. One
@@ -457,20 +445,20 @@
- Tuning systems must weigh the purity of thirds and fifths. A
- Pythagorean tuning system made from pure fractions will include many
- different "fifths" and "thirds" at different points in the scale,
- especially when using basic ratios to determine a 12-tone scale. Each
- musical key sounds highly distinctive, and some intervals may be
- considered dissonant or harsh.
+ Tuning systems must weigh the purity of thirds and fifths. A just
+ tuning system made from pure fractions might use as its basis the
+ difference between 3:2 and 4:3, which constitutes a semitone. Such a
+ scale implies different ratios between "fifths" and "thirds" at
+ different points in the scale. Each mode can sound highly distinctive,
+ and some intervals may be considered dissonant or harsh.
In a sense, 12-tone equal temperament "bends" all of the notes such
that the fifths are more consisent, making it easier to modulate
- between keys, though other intervals (like thirds) are far from a pure
- interval. This process invokes irrational numbers, and creates
- in-between intervals which do not exist anywhere in the Lambdoma, no
+ between keys, though other intervals (like thirds) are quite different
+ from a interval. This process invokes irrational numbers, and creates
+ in-between intervals which do not exist anywhere on the Lambdoma, no
matter how far out you go. Equal-tempered semitones are separated by a
ratio of the 12th root of 2 (1:
Jules LaPlace / asdf.us / 2018-2025
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