Part 3: Hear and measure relationships · Lesson 022 / 117
Count letters to get the interval number
Understand why a third is not necessarily three frets.
Interval names use a number and, often, a quality. Today we learn the number. Count the letter names from the lower note to the upper note, including both endpoints.
C to E spans C, D, E: three letters, so it is some kind of third. C to G spans C, D, E, F, G: five letters, so it is some kind of fifth. Accidentals do not change this letter count: C to Eb still uses the letters C through E.
Notice the two counting jobs. For a fret distance, the starting position is zero movement. For the interval number, both endpoint letters are included. Confusing these jobs creates answers that are off by one.
Do not learn complicated enharmonic interval spellings today. Work with plainly named pairs. Next we will add the semitone distance to tell different kinds of third apart.
Hear it
Third
Audio fileFour-beat count-in · 60 BPM · Warm sampled electric guitar. Listen once before playing along.
A concrete example
C–E: third, because C D E gives three letters. C–G: fifth, because C D E F G gives five. Neither name tells you to move three or five frets.
Try it, slowly
- Write C through E and circle both endpoints.
- Count the letters for D–F and G–B.
- Play C–E on the B string and compare its four-fret distance with its interval number three.
Check one idea
Why is C–E called a third even though it spans four semitones?
Show the explanation
Third comes from the three inclusive letter names C–D–E. Four semitones will identify its quality as major in the next lesson.
A good place to stop
You can keep inclusive letter counting separate from counting fret movements.
Return to the example after a short break. A clear explanation matters more than speed.