Interval Identification | Diminished And Augmented Intervals (9 of 10)
A diminished interval occurs when a minor or Perfect interval is flattened by one half step.
Diminished Intervals from Minor
For example, in video seven of this series we learned that, because the two notes are separated by ten consecutive half steps, an interval of a minor seventh above the note A is the note G.
Knowing that a diminished interval is created when a minor interval is flattened by a half step, if an interval of a minor seventh above A is G, then an interval of a diminished seventh above A would be the note G-flat.
Now, the note G-flat is the enharmonic equivalent of the note F-sharp, meaning both letter names are in fact the same pitch.
Therefore, you may have noticed that an interval of a diminished seventh above the note A sounds exactly the same as an interval of a Major sixth.
However, because we are currently discussing an interval of a diminished seventh, we must use the letter name G-flat rather than F-sharp. That is because an interval of a diminished seventh is an alteration of a minor seventh interval which is in fact the note G.
Diminished Intervals from Perfect
As stated earlier, another way that a diminished interval is created is when a Perfect interval is flattened by one half step.
For example, in video five we learned that an interval of a Perfect fifth above the note C is the note G.