The Intervals of the Seventh and Octave

Review

Interval Quality

Perfect intervals have three qualities: Perfect, Augmented, and Diminished.

1. Perfect: The top note is a note in the major scale built from the bottom note.
2. Diminished: The top note is a half-step lower than the note in the major scale built from the bottom note.
3. Augmented: The top note is a half-step higher than the note in the major scale built from the bottom note.

Major intervals are have four possible qualities: Major, Minor, Augmented, and Diminished.

1. Major: The top note is a note in the major scale built from the bottom note.
2. Minor: The top note is a half-step lower than the note the major scale built from the bottom note.
3. Diminished: The top note is a whole-step lower than the note in the major scale built from the bottom note.
4. Augmented: The top note is a half-step higher than the note in the major scale built from the bottom note.

To review Intervals go to Understanding Intervals.

T review Perfect Intervals go to Perfect Intervals.

For review on Major Intervals go to Major Intervals.

So far, we have practiced the intervals of Unison through the 6th. Let's see what this looks like with the intervals of a 7th and Octave.

Scales and Key Signatures

Reminder: a key signature is just a short hand for all the accidentals in a key. The easiest way to know if a note is part of a scale is to have your key signatures memorized.

To review Major Key Signatures go to Major Key Signatures.

To review Major Scales go to Major Scales.

Major 7th and Perfect Octave

The bottom note is an A. Notice how the top notes, G♯ and A, are both notes in the A major scale. In other words, there is a G♯ in the key signature for the key of A but no accidental for the pitch A. Therefore, this is a Major 7th (M7) and a Perfect Octave (P8). (A major 7th is also the distance of 11 half-steps. A perfect octave is the distance of 12 half-steps.)

Augmented 7th and Octave

Notice how the top notes, G double-sharp and A♯, are both a half-step higher than the notes in the A major scale, G♯ and A-natural. In other words, there are no double sharps in the key signature for the key of A (or any key) and the F double-sharp is one half-step higher than the F♯ in the key. There is no A♯ in the key signature and the A♯ is one half-step higher than the A-natural that is in the key. Therefore, this is an Augmented 7th (A7) and Augmented Octave (A8). (An augmented 7th is the distance of 12 half-steps. An augmented octave is the distance of 13 half-steps.)

Minor 7th and Diminished Octave

Notice how the top notes, G (natural) and A♭, are a half-step lower than the notes in the A major scale, G♯ and A-natural. In other words, G is sharp in the key signature for the key of A and G natural is one half-step lower than the G♯ in the key. Because a 7th is a major interval, this is a minor 7th (m7). The A in the key is natural but the A in the interval is flat. Because the octave is a perfect interval, this is a diminished octave (d8). (A minor 7th is the distance of 10 half-steps. A diminished octave is the distance of 11 half-steps)

Diminished 7th

Notice how the top note, G♭, is a whole-step lower than the note in the A major scale, G♯. In other words, there are no flats in the key signature for the key of A and G♭ is one whole-step lower than the G♯ in the key. Therefore, this is a diminished 7th (d7). (A diminished 7th is the distance of 9 half-steps.)