How to classify any interval · Intervals · Music theory
It is always done with the same steps, listed below. Two worked cases:
How to classify any interval
It is always done with the same steps, listed below. Two worked cases:
E–G: in E major the 3rd is G♯; G is a half step lower, so it is a minor 3rd. F–B: in F major the 4th is B♭; B is a half step higher, so it is an augmented 4th.
If the lower note makes the scale awkward (D♯, F♭), just move both notes by the same amount, because the interval does not change: D♯–A♯ is the same as D–A, a perfect 5th. You can also count the half steps and compare them with the table in “Major, minor and perfect”, without forgetting the number.
When the interval descends or is heavily altered
A descending interval is classified the same way, taking the lower note as the reference: for B–D going down, think of the scale of D. If the lower note has an awkward scale, there are two ways out: move both notes equally, or remove the accidentals, classify the natural interval and put them back, counting the effect of each one.
For example, C♯–E♭: without accidentals, C–E is a major 3rd. Raising the lower note reduces it to minor and lowering the upper note reduces it again: a diminished 3rd. It sounds like a whole step, but it is written and behaves as a 3rd.