# Intervals

An interval is the inclusive distance between two notes. An interval may be **melodic** or **harmonic**.

Each melodic or harmonic interval has a **number** and a **quality**, we will see this later.

## Melodic interval

A melodic interval is an interval in a melody when notes are played one after the other:

## Harmonic interval

An harmonic interval is an interval between two notes in the same chord, when notes are been playing at the same time:

## Number of an interval

Each interval has a **number** that is the number of letter name it contains. For example, if you consider the interval starting from C and ending on G, you must count like this: C-D-E-F-G = 1-2-3-4-5, so this interval is a fifth (5th).

### List of interval numbers

1 **Unison**

2 **Second**

3 **Third**

4 **Fourth**

5 **Fifth**

6 **Sixth**

7 **Seventh**

8 **Octave**

9 **Ninth**

10 **Tenth**

11 **Eleventh**

12 **Twelfth**

13 **Thirteenth**

.. ......

.. ......

and so on

## Ascending and descending intervals

An interval may be ascending or descending:

## Interval quality

To identify intervals with precision, intervals have a quality identifier.

Qualities of intervals may be one of them:

- **Perfect**

- **Major**

- **Minor**

- **Augmented**

- **Diminished**

- **Doubly diminished**

- **Doubly augmented**

But all intervals can't be identified with some of all identifiers, here are all possibility:

Major | Minor | Perfect | Augmented | Diminished | Doubly augmented | Doubly diminished | |

Unison | |||||||

Second | |||||||

Third | |||||||

Fourth | |||||||

Fifth | |||||||

Sixth | |||||||

Seventh | |||||||

Octave |

Below is the same table but classified to be more clear:

Major | Minor | Perfect | Augmented | Diminished | Doubly augmented | Doubly diminished | |

Unison | |||||||

Octave | |||||||

Fourth | |||||||

Fifth | |||||||

Second | |||||||

Third | |||||||

Sixth | |||||||

Seventh |

Only **unisons**, **fourths**, **fifths** and **octaves** can be __perfects__ but never *major* or *minor*.

Only **seconds**, **thirds**, **sixths** and **sevenths** can be __major__ or __minor__ but never *perfects*.

## Intervals qualities in the C Major scale

Starting from the first note of the C Major scale, all intervals are only **Majors** or **Perfects**

C - C | Unison | Perfect |

C - D | Second | Major |

C - E | Third | Major |

C - F | Fourth | Perfect |

C - G | Fifth | Perfect |

C - A | Sixth | Major |

C - B | Seventh | Major |

C - C | Octave | Perfect |

__You should keep in mind that in all Major scales, from the first note of the Major scale, all intervals are only Majors or Perfects.__

## Augmented and diminished intervals

- When a half step (semitone ) is added to a **major** interval, it results in an **augmented** interval

- When a half step (semitone ) is removed to a **major** interval, it results in a **diminished** interval

- When a half step (semitone ) is added to a **perfect** interval, it results in an **augmented** interval

- When a half step (semitone ) is removed to a **perfect** interval, it results in a **diminished** interval

- When a half step (semitone ) is added to an **augmented** interval, it results in a **doubly augmented** interval

- When a half step (semitone ) is removed to a **diminished** interval, it results in a **doubly diminished** interval

## Examples of augmented and diminished intervals

## Examples of minors, majors, augmented and diminished intervals

## How to find interval name and quality?

For example, let's consider the interval C - B♭ :

C D E F G A B = 1 2 3 4 5 6 7 = Seventh

The name of the interval C - B♭ is Seventh.

Now we will find the quality of this interval:

We know that from the first note of the C Major scale, all intervals are only Majors or Perfects and that only seconds, thirds, sixths and **sevenths** can be major or minor but never perfects...

So the interval C - B natural is a seventh major, **so the interval C - B♭ is a seventh minor**!

That's all! Easy no?

## Enharmonic

Two notes are **enharmonic** when they are tuning the same pitch but spelled or named differently, examples:

## Inversion of intervals

An interval may be inverted by raising the lower pitch an octave or lowering the upper pitch an octave, example:

**unison** become **octave**

**second** become **seventh**

**third** become **sixth**

**fourth** become **fifth**

**fifth** become **fourth**

**sixth** become **third**

**seventh** become **second**

**octave** become **unison**

During inversions, intervals qualities change like this:

- **Diminished** intervals become **augmented**

- **Minors** intervals become **majors**

- **Majors** intervals become **minors**

- **Augmented** intervals become **diminished**

- **Perfects** stay **perfects**

## Compound intervals

A compound interval is an interval greater than one octave:

The quality of a compound interval is the same as the corresponding simple interval.

External links to learn more about:

1 - https://www.dolmetsch.com/musictheory12.htm

2 - https://en.wikipedia.org/wiki/Interval_(music)

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