Intervals theory
Intervals are the distances between two notes, which can be harmonic (played together) or melodic (played in sequence).
Intervals qualities and types
There are different types and qualities of intervals:
- Intervals: Unison, Second, Third, Fourth, Fifth, Sixth, Seventh, and Octave
- Qualities: Diminished, Minor, Perfect, Major, and Augmented
Summary of possible combination of quality and interval:
| Intervals | Dim. | Min. | Perf. | Maj. | Aug. |
|---|---|---|---|---|---|
| Unison | ✓ | ✓ | ✓ | ||
| Second | ✓ | ✓ | ✓ | ✓ | |
| Third | ✓ | ✓ | ✓ | ✓ | |
| Fourth | ✓ | ✓ | ✓ | ||
| Fifth | ✓ | ✓ | ✓ | ||
| Sixth | ✓ | ✓ | ✓ | ✓ | |
| Seventh | ✓ | ✓ | ✓ | ✓ | |
| Octave | ✓ | ✓ | ✓ |
Side note: Most of the time, the quality "perfect" is ommited.
Intervals distances
Summary of intervals and distances:
| Dist. | Common name | Less common name |
|---|---|---|
| 0 | Unison (Perfect) | Second Diminished |
| 0.5 | Second Minor | Unison Augmented |
| 1 | Second Major | Third Diminished |
| 1.5 | Third Minor | Second Augmented |
| 2 | Third Major | Fourth Diminished |
| 2.5 | Fourth (Perfect) | Third Augmented |
| 3 | Tritone | Fourth Augmented / Fifth Diminished |
| 3.5 | Fifth (Perfect) | Sixth Diminished |
| 4 | Sixth Minor | Fifth Augmented |
| 4.5 | Sixth Major | Seventh Diminished |
| 5 | Seventh Minor | Sixth Augmented |
| 5.5 | Seventh Major | Octave Diminished |
| 6 | Octave (Perfect) | Seventh Augmented |
Additional qualification of intervals
An interval can be
- melodic (separated notes) or harmonic (notes together).
- ascending or descending.
Side note: An enharmonic is when two different notes sound the same.