Intervals II: Altered Intervals

The perfect and major intervals covered in my last post can be altered, either increased or decreased in size.

When we increase the size of an interval, it is called augmentation; when we decrease the size of an interval, it is called diminution.

When an interval changes in size, so does the name we give it.

This post will cover minor, diminished and augmented intervals. It will also provide common fingerings for each interval, along with instruction on how to play them on a guitar with any root note.

Minor Intervals

When we decrease a major interval by a half step, it becomes a minor interval.

Minor Seconds

The distance between a C and a D is a major second. If we decrease the size of the interval by a half step — lowering the D to a Db — it becomes a minor second.

The distance between a C and a Db is a minor second (fig.1a).

The interval contains two scale steps and one half step between the notes.

Minor Thirds

The distance between a C and an E is a major third. If we decrease the size of the interval by a half step — lowering the E to an Eb — it becomes a minor third.

The distance between a C and an Eb is a minor third (fig.1b).

The interval contains three scale steps and three half steps between the notes.

Minor Sixths

The distance between a C and an A is a major sixth. If we decrease the size of the interval by a half step — lowering the A to an Ab — it becomes a minor sixth.

The distance between a C and an Ab is a minor sixth (fig.1c).

The interval contains six scale steps and eight half steps between the notes.

Minor Sevenths

The distance between a C and a B is a major seventh. If we decrease the size of the interval by a half step —lowering the B to a Bb — it becomes a minor seventh.

The distance between a C and a Bb is a minor seventh (fig.1d).

The interval contains seven scale steps and ten half steps between the notes.

Fig.1

Diminished Intervals

When we decrease a perfect interval by a half step, it becomes a diminished interval.

Diminished Fourths

The distance between a C and an F is a perfect fourth. If we decrease the size of the interval by a half step —lowering the F to an Fb — it becomes a diminished fourth.

The distance between a C and an Fb is a diminished fourth (fig.2a).

The interval contains four scale steps and four half steps between the notes.

A diminished fourth interval is the enharmonic equivalent of a major third interval (see section entitled Enharmonic Equivalents below).

Diminished Fifths

The distance between a C and a G is a perfect fifth. If we decrease the size of the interval by a half step — lowering the G to a Gb — it becomes a diminished fifth.

The distance between a C and a Gb is a diminished fifth (fig.2b).

The interval contains five scale steps and six half steps between the notes.

Fig.2

Augmented Intervals

When we increase a perfect interval by a half step, it becomes an augmented interval.

Augmented Fourths

The distance between a C and an F is a perfect fourth. If we increase the size of the interval by a half step — raising the F to an F# — it becomes an augmented fourth.

The distance between a C and an F# is an augmented fourth (fig.3a).

The interval contains four scale steps and six half steps between the notes.

An augmented fourth interval is the enharmonic equivalent of a diminished fifth interval.

Augmented Fifths

The distance between a C and a G is a perfect fifth. If we increase the size of the interval by a half step — raising the G to a G# — it becomes an augmented fifth.

The distance between a C and a G# is an augmented fifth (fig.3b).

The interval contains five scale steps and eight half steps between the notes.

An augmented fifth interval is the enharmonic equivalent of a minor sixth interval.

Fig.3

Enharmonic Equivalent Intervals

The same interval can have two (or more) names, depending on how we spell it.

Major Third and Diminished Fourth Intervals

A major third interval and a diminished fourth interval both contain four half steps and sound exactly the same when played.

The only difference between them is that a major third interval (fig.4a) contains three scale steps (C, D and E) and a diminished fourth interval (fig.4b) contains four scale steps (C, D, E and F).

Fig.4

Augmented Fourth and Diminished Fifth Intervals

An augmented fourth interval and a diminished fifth interval both contain six half steps and sound exactly the same when played.

The only difference between them is that an augmented fourth interval (fig.5a) contains four scale steps (C, D, E and F) and a diminished fifth interval (fig.5b) contains five scale steps (C, D, E, F and G).

Fig.5

Augmented Fifth and Minor Sixth Intervals

And an augmented fifth interval and a minor sixth interval both contain eight half steps and sound exactly the same when played.

The only difference between them is that an augmented fifth interval (fig.6a) contains five scale steps (C, D, E, F and G) and a minor sixth interval (fig.6b) contains six scale steps (C, D, E, F, G and A).

Fig.6

Altered Intervals on a Guitar

An interval can be played on any two strings.

The interval shapes and examples shown in this post are all played on strings five and six.

These same shapes will work on any two adjacent strings except for strings two and three. The interval shapes for the second and third strings are different because of the way a guitar is tuned.

Minor Seconds

The diagram shown in fig.7a illustrates the relationship between any given note and the note a minor second above it on a guitar.

Fig.7b provides the fingering to play the interval.

Fig.7

To play a C and the note a minor second above it:

  • Place your fourth finger on the C on the sixth string, eighth fret (fig.8a).
  • Place your first finger on the fifth string, fourth fret — Db.

Db is a minor second above C.

To play an A and the note a minor second above it:

  • Place your fourth finger on the A on the sixth string, fifth fret (fig.8b).
  • Place your first finger on the fifth string, first fret — Bb.

Bb is a minor second above A.

Fig.8

Minor Thirds

The diagram shown in fig.9a illustrates the relationship between any given note and the note a minor third above it on a guitar.

Fig.9b provides the fingering to play the interval.

Fig.9

To play a C and the note a minor third above it:

  • Place your third finger on the C on the sixth string, eighth fret (fig.10a).
  • Place your first finger on the fifth string, sixth fret — Eb.

Eb is a minor third above C.

To play an A and the note a minor third above it:

  • Place your third finger on the A on the sixth string, fifth fret (fig.10b).
  • Place your first finger on the fifth string, third fret — C.

C is a minor third above A.

Minor Sixths

The diagram shown in fig.11a illustrates the relationship between any given note and the note a minor sixth above it on a guitar.

Fig.11b provides the fingering to play the interval.

Fig.11

To play a C and the note a minor sixth above it:

  • Place your first finger on the C on the sixth string, eighth fret (fig.12a).
  • Place your fourth finger on the fifth string, 11th fret — Ab.

Ab is a minor sixth above C.

To play an A and the note a minor sixth above it:

  • Place your first finger on the A on the sixth string, fifth fret (fig.12b).
  • Place your fourth finger on the fifth string, eighth fret — F.

F is a minor sixth above A.

Fig.12

Minor Seventh

The diagram shown in fig.13a illustrates the relationship between any given note and the note a minor seventh above it on a guitar.

Fig.13b provides the fingering to play the interval.

Fig.13

To play a C and the note a minor seventh above it:

  • Place your first finger on the C on the sixth string, eighth fret (fig.14a).
  • Place your fourth finger on the fifth string, 13th fret — Bb.

Bb is a minor seventh above C.

To play an A and the note a minor seventh above it:

  • Place your first finger on the A on the sixth string, fifth fret (fig.14b).
  • Place your fourth finger on the fifth string, 10th fret — G.

G is a minor seventh above A.

Fig.14

Diminished Fifths

The diagram shown in fig.15a illustrates the relationship between any given note and the note a diminished fifth above it on a guitar.

Fig.15b provides the fingering to play the interval.

Fig.15

To play a C and the note a diminished fifth above it:

  • Place your first finger on the C on the sixth string, eighth fret (fig.16a).
  • Place your second finger on the fifth string, ninth fret — Gb.

Gb is a diminished fifth above C.

To play an A and the note a diminished fifth above it:

  • Place your first finger on the A on the sixth string, fifth fret (fig.16b).
  • Place your second finger on the fifth string, sixth fret — Eb.

Eb is a diminished fifth above A.

Fig.16

Altered Interval Sound and Qualities

Each interval evokes its own quality, sound or feeling. Some intervals are consonant — the notes blend well when played together. And some are dissonant — the notes tend to clash with one another.

Minor third and minor sixth intervals are considered to be relatively consonant.

Minor second, minor seventh and diminished fifth intervals are considered dissonant.

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