SongTrellis
Music and Musical Know-how For You

Why only 12 possible? Weve heard that pianos usually can play 88 different pitches.

Yes, but when you play a note that's twelve piano steps higher or lower than any pitch you choose, your ear hears that as a pitch that has the same meaning as the original, but which must be be sung with a higher or lower voice. This effect makes it possible for people with low deep voices to sing the same a melody with someone who sings high or in a middle register.

The design of piano's actually give a hint that this kind of thing must be going on. Every 12 notes on the piano, the pattern of black and white keys on the instrument repeats again.

The distance in pitch between a melody note and the next lower note that is named the same as the root of the chord is called the harmonic interval. If for example, your melody played a G pitch above a chord whose root pitch was C, you could step 7 steps down on the piano down to the next lower C pitch. We could say that the harmonic interval distance from the C root up to G pitch is 7.

The following table shows the size of harmonic intervals measured from 0 to 11, lists the names that musicians give to that interval size, and then shows the color the SongTrellis Music Editor assigns to that size of harmonic interval.

Harmonic Interval Size	Usual Names	Color code used by SongTrellis Editor
0	unison,octave	black
1	minor 2nd, minor 9th,flatted 9th	brown
2	Major 2nd, Major 9th	green
3	minor 3rd, sharped 9th	dark blue
4	Major 3rd, Major 10th	light blue
5	Perfect 4th	purple
6	Augmented 4th, flatted 5th,	magenta
	Augmented 11th
7	Perfect 5th	red
8	Augmented 5th, Flatted 6th,	forest green
	Flat 13th
9	Major 6th, 13th	tan
10	minor 7th, augmented 6th	gold
11	Major 7th	silverblue

To summarize this coloring scheme, roots and octaves are black, perfect 5ths are red, major 3rds are light blue, minor thirds are dark blue, major 7ths are silver-grey, minor 7ths are golden, major 2nds(9ths) are green, minor 2nds(minor ninths) are brown, perfect 4ths are purple, flatted 5ths are magenta, major 6ths are tan, minor 6ths are forest green.