All About 3rds

FRIDAY, September 27, 2019

All About 3rds…

Any 3 (3rd) uses two letters and skips one. For example, C to E is a 3th. Either note can be sharped, or flatted, or both. One can be sharp and the other flat. Anything is theoretically possible. Regardless how strange it looks or feels in your hands, or how weird it sounds, it’s a 3rd. Some possibilities are so weird or impractical that you will probably never see them or write them. But they are theoretically possible.As you play intervals you may see two black notes, two white notes or one of each. Now, here are the 3rds that are used frequently:

  • 3 (major 3rd) does not have a name for the sound only, but think of it as a “bitone” (my word, not a standard term) because the total width is two whole steps.. The two keys you play can be both colors, or both can be white, or both can be black keys. It is the default 3rd, just the number 3 in chords, because it is the 3rd note in a major scale.
  • b3 (minor 3nd) is either one piano key smaller than 3 (major 3rd) or one piano key bigger than 2 (major 2nd) The total width is one and a half steps.
  • b3 (diminished 3nd) is another way to write a whole step. It is awkward visually but appears in inverted 7 chords.

3 thoughts on “All About 3rds

  1. I especially liked the fact that the PDF on thirds begins with the harmonic minor scale and the augmented second it contains, which is the enharmonic equivalent to the minor third. There are many books and sites out there on theory. It would not be useful to have yet another one saying the same thing. Most are abstract, not connecting to music. The aug2 is presented late as an “advanced” thing. Yet students learn early on to play the harmonic minor scale, and it occurs often in music. They are left wondering as they see a 2nd on the page, but hear a 3rd as they play it, and see the same spacing in the piano keys as with some thirds. Why not demystify this early, as you have done here.

  2. I found the black 6 sided stars today in Wingdings, a font I’ve used for maybe 20 years. I was looking for something to highlight things that are all black on the piano. I navigate by color and sound. I’m just explaining now what I see for myself. So I now have a template for all the other intervals. 🙂

  3. The visual page showing 3rds has given me a better understanding of the concepts involved. It’s logical, taking one step at a time. The stars and arrows are quite helpful.


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