Musical Intervals – An Important Part of Music Theory

What are musical intervals? In music theory, an interval is a distance between any two musical sounds with regard to pitch. Knowing musical intervals is essential. It is the basis of all musical construction.

Moreover, intervals are examples of the simplest harmony used in music. It is also called two-part harmony.

We count the interval from the lower note to the upper including both notes. In a diatonic scale, the smallest interval is a semitone (half step).

In this post, we are reviewing various kinds of intervals and how to construct them.

Harmonic Interval and Melodic Interval

In terms of harmonic vs melodic intervals, they are two different concepts. Harmonic intervals sound together, while melodic intervals are sequential.

harmonic interval

A harmonic interval is also known as a vertical interval. For example, when we play two tones simultaneously, we play a harmonic interval. The notes are written vertically on a clef.

melodic interval

A melodic interval is also a horizontal interval. We write the notes horizontally and play them one after another.

same intervals

Intervals remain the same whether we use the treble clef or bass clef. For example, E to G is three intervals on both treble clef and bass clef.

Intervals in C Major

An Interval name is according to the number of letters included. For example from C to E, it involves three letters: C > D > E, hence it is a third.

When two tones are the same without the pitch difference, we call it the Prime or Unison. Strictly speaking, it is not an interval.

Interval Names

Let’s use C Major scale to show the names of intervals. The words below the notes indicate the kind of interval. As a convention, the interval names use the ordinal numbers.

musical interval names

Minor Intervals

We call Second, Third, Sixth, and Seventh Major intervals because they have a corresponding Minor Interval. For instance, the Major Second from C to D has a whole step (two half-steps). If we lower the D to D♭, from C to D♭ is one half-step and we write C D♭. To avoid confusion we do not recommend you to write C C♯, even though D♭ and C♯ are enharmonic tones, because this would not include two letters to be called a Second. Hence C D♭ is the Minor Second.

The following are the corresponding minor intervals of the second, third, sixth, and seventh major intervals.

Minor intervals

We call the Fourth and Fifth intervals the Perfect interval, not using major or minor. However, if we reduce a Perfect Fourth (or Fifth) by one half-step, we get the Diminished Fourth (or Fifth). On the other hand, if we increase a Perfect Fourth (or Fifth) by one half-step, we have an Augmented Fourth (or Fifth).

diminished-and-augmented-intervals

Abbreviated interval notations:

  • P = Perfect
  • M = Major
  • m = minor
  • d = diminished
  • A = Augmented
  • 1-7 = corresponding ordinal numbers

Most Common Augmented Intervals

common augmented intervals

Most Common Diminished Intervals

common diminished intervals

Inversion

Intervals may be Inverted. This means that the tones change their relative positions. It is usually by moving one of the tones by an octave while the other remains at the same position. Inversion in an interval can happen with either the top or bottom tone.

The inversion of an interval changes the character of the interval including the name and qualities.

Interval names change in inverted intervals.

musical interval name changes

All interval qualities are reversed except Perfect:

  • Major becomes Minor
  • Minor becomes Major
  • Diminished becomes Augmented
  • Augmented becomes Diminished

More examples of inversion –

inversion examples

Intervals in the D Major

The Major Scale furnishes us with a standard of measurement for all Intervals. We are able to apply the same rules to any major scale. Let’s use D Major for the exercise.

d-major-normal-intervals
D Major Normal Intervals
minor intervals for d major scale
Minor Intervals
d major dim and aug intervals
Diminished and Augmented Intervals

To Wrap Up…

In this post, we explained several things about musical intervals which are a foundation for music construction.

  • In major scales, we have Perfect and Major Intervals.
  • If a Perfect or Major interval is expanded by half step it becomes an Augmented interval.
  • When a distance between two notes of a Major interval is lessened one half-step, it is called a Minor Interval.
  • If a Perfect interval is reduced by a half-step, it then becomes a Diminished Interval.

It may seem confusing in some ways, however, if you start with C Major and get well versed in its various intervals, you will find it is easier to move to other scales. Keep practicing. Good luck!

Related: Music Fundamentals Series

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