# Created: 2021-07-19; Modified: 2021-08-22
Why does a melody sounds good? And what can we learn to compose more?
distance(220Hz, 440Hz) == distance(440Hz, 880Hz).
(nHz, knHz) where k >= 1are considered the most perfect.
log2logarithmic grid for frequency. Base 2 is chosen because
(nHz, 2nHz)are the closest two difference notes that sounds incredibly hamonious.
Note(n) = sqrt[n/12](2) * Note(0).
Before the mathematical tool to deal with irrational number was in place, people sought to deduce notes base on the next most hamonious sound,
3n/2Hz. In those systems, intervals between notes aren’t equal, and therefore it’s often impossible to variate a melody by changing the base note of its scale (because the physical interval pattern is changed and the melody sounds off). See Pythagorean tuning or 十二律 for more details.