More Complex Intervals

We learned in an earlier post the different intervals from a 2nd up to an octave. I am now going to discuss intervals in more detail.

The different types of intervals are augmented, major, minor, perfect and diminished.

When working out intervals, the rules below should be remembered.

When a major interval is a semitone larger it becomes augmented.

When a major interval is a semitone smaller it becomes minor.

When a minor interval is a semitone larger it becomes major.

When a minor interval is a semitone smaller it becomes diminished.

When a perfect interval is a semitone larger it becomes augmented.

When a perfect interval is a semitone smaller it becomes diminished.

If we remember the degrees; 2nd major, 3rd major, 4th perfect, 5th perfect, 6th major, 7th major, octave perfect, we can work out the type of interval easily.

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If we look at the two notes, D to A. We count up starting on D up to A; D, E, F, G, A. It is five notes which makes the interval a 5th. The interval is not just called a 5th, there is a type of interval. It is called a perfect 5th because an interval of a 5th is called perfect. However, this only applies if the top note of the interval is in the scale. For example, we use the scale of D major because the lower note of the interval is D. In D major the 5th note of the scale is an A.

If we take another interval, D to F. In the scale of D major, an F is an F#, so an F natural would make the interval smaller because there are less semitones from D to F natural than from D to F#. D, D#, E, F is 3 semitones and D, D#, E, F, F# is 4 semitones. So this interval would be called a minor 3rd because it is a major interval made smaller by a semitone.

If we take the perfect 5th interval of D to A and make the A an A#. This interval would become bigger by a semitone. It would become an augmented 5th. If the perfect 5th interval is made smaller D to Ab it would become a diminished 5th.

If we take the interval C to Bb. This interval is a major 7th up to B, but when the interval is made smaller to a Bb it becomes a minor 7th. If this interval C to B becomes C to Bbb (double flat), it has been made smaller by 2 semitones so C to B is a major 7th, C to Bb is a minor 7th and C to Bbb is a diminished 7th. If the interval C to B becomes B# it would become an augmented 7th.

Remember:

A major interval made larger by 1 semitone becomes augmented, when it is made smaller by 1 semitone it becomes minor.

A minor interval made larger by 1 semitone it becomes major, when it is made smaller by 1 semitone it becomes diminished.

A perfect interval made larger by 1 semitone it becomes augmented, when made smaller by 1 semitone it becomes diminished.

Taylor, E. (n.d.). Music theory in practice, grade 4. 1st ed. London: Associated Board of the Royal Schools of Music. pp. 26 and 27.

Taylor, E. (n.d.). Music theory in practice, grade 3. 1st ed. London: Associated Board of the Royal Schools of Music. p. 30.