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Intervals

Chromatic and Diatonic

If you were to play all twelve notes in sequence, i.e. one fret at a time in either direction, or every key on the piano, you would produce a chromatic scale

A diatonic scale is just an arrangement of semitones (one fret) and tones (two frets), which reduces a chromatic scale to from 12 steps down to 7 steps. The eighth note is the same as the first only one octave higher. (Latin octavus: eighth)

Intervals on one string

An interval describes the special relationship between any two notes whether they are played successively (melody) or simultaneously (harmony), and every interval has it’s own unique sonic personality resulting from its two combined parent notes. If the parents are identical in pitch, this is called a unison. Two notes with the same name but from opposite ends of a scale, produce an octave.

intervals fingerboard.png

Interval names

In western music an octave is divided into twelve equal notes which can be seen above on the low E string of the guitar. After the 12th fret, usually signified by double dots on the fingerboard, the pattern is repeated through the next octave.

Beginning on any note and playing all twelve notes in a row would produce a chromatic scale.

Major Scale Intervals

The major scale is by far the most common scale used in western music. If you have seen the Sound of Music you may remember that it is the scale that produces the familiar do, re, mi, fa, so, la, ti, do sound.

A C major scale contains no sharps of flats which makes it a very easy scale to play on the piano as it’s just all the white notes.

The major scale is always arranged as follows: Tone-Tone-Semitone-Tone-Tone-Tone-Semitone. Notice that you have two tones together and then after the semitone, three tones together and next time you see a piano keyboard, take a look at how the black keys appear. The notes skipped in a C major scale, the black notes, are called Sharps (♯) and flats (♭) and in any of the other 11 major scales, white keys will be substituted with anywhere between 1 to 7 of them

Intervals within a major scale are numbered and qualified as either major or perfect.

C-C (same pitch) Perfect Unison
C-D Major 2nd
C-E Major 3rd
C-F Perfect 4th
C-G Perfect 5th
C-A Major 6th
C-B Major 7th
C-C (one octave above) Perfect Octave

The notes between the notes listed above are described in relation to these intervals and adjusted to become minor, augmented or diminished. A semitone below a major 2nd, 3rd, 6th  or 7th  simply becomes a minor 2nd, 3rd, 6th or 7th . A semitone below a 5th is a diminished 5th and a semitone above a 4th or a 5th becomes an augmented 4th or 5th. The note between the 4th and the 5th is also referred to as the tri-tone, because, as you might have guessed, it is three tones from the tonic. Incidentally, three tones=six semitones which makes the ♯4//♭5 the precise centre of the scale.

Rules

A major interval, reduced by one semitone, becomes minor

A minor interval increased by one semitone becomes major

A perfect or major interval, increased by one semitone, becomes augmented

A perfect or minor interval, reduced by one semitone, becomes diminished

Inverted Intervals

When a major interval is inverted, i.e. the lower of the two notes is raised an octave, or the higher one is dropped an octave, the interval becomes minor e.g. C to D is a major 2nd, whereas D to C is a minor 7th. Similarly, when minor intervals are inverted, they become major. Perfect fourths invert to become perfect fifths and visa versa.

In order to help train your ear to recognise each of the different intervals, it can be useful to associate the different sounds with songs you already know. The videos below offer examples of all the possible combinations, both ascending and descending. The repeated intervals are the ones to focus your listening on.

This first one includes a variety of different songs all in their original keys.

This is an edited version. Some of the songs have been pitch adjusted to help with easier comparisons. Also includes a few sine waves in the mix.

This is another edit to illustrate the intervals against their inverted counterparts. Again with sine waves and some pitch shifting.