How to Identify Musical Intervals (Music Theory)

We cover the technically proper way to identify musical intervals, with some exercises to drill it. Any questions on how to name intervals, let me know in the comments.

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Exercise Key:

1. E B = perfect fifth
2. Ab D = augmented fourth
3. D Db = diminished octave

4. A F# = major sixth
5. Eb Gb = minor third
6. F E = major seventh

7. F# E = minor seventh
8. G C# = augmented fourth
9. Bb D# = augmented third

Recap + extra info:

An interval is how we describe the musical distance between two notes. Intervals are named by the number of alphabetical letters as well as the actual distance in half-steps between the two notes.

So interval names consist of two parts:

-a NUMBER for the size of the interval (unison, second, third, fourth, fifth, sixth, seventh, or octave)
-a name for the QUALITY of the interval (major, minor, perfect, diminished, or augmented)

The NUMBER is determined by how many alphabetical letters there are between the two intervals, counting from the lower interval to the higher interval, and including both notes.

Between A and C#, where A is the lower note, the interval number is a THIRD (count: A B C#...3).

Between F and E, where F is the lower note, the interval number is a SEVENTH (count: F G A B C D E...7).

Note that we don't care at all about accidentals. You just include one count of each alphabetical letter between the two notes.

If the two notes to be described are the same, like D and D, or the same but with different accidentals, like C and C#, the term we use for the NUMBER is 'unison.' Similarly, a spread of 8 notes apart is called an octave--C3 to C4, for example.

Figuring out the QUALITY part of an interval name requires the NUMBER part to be figured out first, because there are two naming schemes depending on the NUMBER of the interval.

Unisons, Fourths, Fifths and Octaves can be: Diminished, Perfect, or Augmented.

Seconds, Thirds, Sixths and Sevenths can be: Diminished, Minor, Major or Augmented.

For Unisons, Fourths, Fifths and Octaves...

-if the upper note is in the key of the lower note, that interval is PERFECT. As in the case of C-G. (G is in the key of C major--so this interval is perfect.)

-if the upper note is one half-step higher than what is naturally in the key of the lower note, that interval is AUGMENTED. As in the case of C-G#. (G# is one half-step higher than what would have been in the key of C major--so this interval is augmented.)

-if the upper note is one half-step lower than what is naturally the key of the lower note, that interval is DIMINISHED. As in the case of C-Gb. (Gb is one half-step lower than what would have been in the key of C major--so this interval is diminished.)

For Seconds, Thirds, Sixths and Sevenths...

-if the upper note is in the key of the lower note, that interval is MAJOR. As in the case of C-E. (E is in the key of C major--so this interval is major, a major third.)

-if the upper note is one half-step higher than what is naturally in the key of the lower note, that interval is AUGMENTED. As in the case of C-E#. (E# is one half-step higher than what would have been in the key of C major--so this interval is augmented, an augmented third.)

-if the upper note is one half-step lower than what is naturally the key of the lower note, that interval is MINOR. As in the case of C-Eb. (Eb is one half-step lower than what would have been in the key of C major--so this interval is minor, a minor third.)

-if the upper note is two half-steps lower than what is naturally the key of the lower note, that interval is DIMINISHED. As in the case of C-Ebb (Ebb is two half-steps lower than what would have been in the key of C major--so this interval is diminished, a diminished third.)