A melodic interval occurs when two notes are played in sequence, one after the other. Intervals can also be harmonic, meaning that the two notes are played together at the same time. Small intervals such as half steps and whole steps combine to form scales. Larger intervals combine to make chords.
Perfect intervals have only one basic form. The first (also called prime or unison), fourth, fifth and eighth (or octave) are all perfect intervals. These intervals are called "perfect" most likely due to the way that these types of intervals sound and that their frequency ratios are simple whole numbers.
We might call these passing harmonic intervals. Two examples are evident in Example 15.1: the minor seventh between the D and the sustained C, and the minor sixth between E and C. Most music theorists would argue that the minor sixth interval is more important than the minor seventh.
Dissonance is a combination of notes that sound unpleasant or harsh. Dissonant interval examples are major and minor seconds, tritone, and major and minor sevenths. The consonant intervals are considered the perfect unison, octave, fifth, fourth and major and minor third and sixth, and their compound forms.
The harmonic minor scale is derivative of the minor scale where the seventh scale degree is raised by a half step. The melodic minor scale is a minor scale with raised sixth and seventh scale degrees, but only when ascending. A descending melodic minor scale is identical to a natural minor scale.
There are five different types of quality of interval which are:
- perfect intervals.
- major intervals.
- augmented intervals.
- minor intervals.
- diminished intervals.
Whole steps and half steps are two types of intervals.
Main intervals
| Number of semitones | Minor, major, or perfect intervals | Augmented or diminished intervals |
|---|
| 1 | Minor second | Augmented unison |
| 2 | Major second | Diminished third |
| 3 | Minor third | Augmented second |
| 4 | Major third | Diminished fourth |
By providing you with known building blocks for melody and harmony, intervals let you compose and improvise music far more easily. The notes you use are no longer chosen purely theoretically or by tedious trial-and-error.
In mathematics, a (real) interval is a set of real numbers that contains all real numbers lying between any two numbers of the set. For example, the set of numbers x satisfying 0 ≤ x ≤ 1 is an interval which contains 0, 1, and all numbers in between.
In music from Western culture, a seventh is a musical interval encompassing seven staff positions (see Interval number for more details), and the major seventh is one of two commonly occurring sevenths. The major seventh spans eleven semitones, its smaller counterpart being the minor seventh, spanning ten semitones.
Interval Classification
| Class | Intervals |
|---|
| Perfect | Unison, Fourth, Fifth, Octave |
| Imperfect | Seconds, Thirds, Sixths, Sevenths |
An Interval is all the numbers between two given numbers. There are three main ways to show intervals: Inequalities, The Number Line and Interval Notation.
Intervals of Increasing/Decreasing/Constant: Interval notation is a popular notation for stating which sections of a graph are increasing, decreasing or constant. Interval notation utilizes portions of the function's domain (x-intervals).
The label of “perfect†in addition to a number describes the interval's quality. These intervals are called perfect because the ratios of their frequencies are simple whole numbers.
The consonant intervals are considered the perfect unison, octave, fifth, fourth and major and minor third and sixth, and their compound forms. An interval is referred to as “perfect†when the harmonic relationship is found in the natural overtone series (namely, the unison 1:1, octave 2:1, fifth 3:2, and fourth 4:3).
The C Major chord has the notes C, E, and G, but can contain the same notes played as an inversion – upside down. In general, the notes of the chord come from the notes of its scale. An interval is the difference between two notes and is one of the building blocks of music.
