In music, an interval represents the distance (or "amplitude", in terms of sound pitch) existing between two notes.

It is possible to find such a distance between two consecutive sounds (melodic interval), or between two sounds played simultaneously (harmonic interval).

The arrangement of the intervals within a larger scale, whose characteristic is the presence of perfect and major intervals, is ours starting point for establishing the alterations we will encounter.

The followings are the distances in tones and semitones of all the intervals:

DISTANCE AND INTERVAL:

- 1st (or unison)                           -> 0

- 2nd minor -> 1 semitone

- 2nd major -> 1 tone

- 2nd increase (or 3rd minor) -> 1 tone and a half

- 3rd major -> 2 tones

- 4th right -> 2 and a half tones

- 4th increase (or 5th decrease) -> 3 tones

- 5th right -> 3 tones and a half

- 5th increased (or 6th minor) -> 4 tones

- 6th major (or 7th diminished) -> 4 tones and a half

- 6th increased (or 7th minor) -> 5 tones

- 7th major -> 5 tones and a half

- 8th -> 6 tones