Music Theory

Interval

Intervals

An interval in music is defined as a distance in pitch between any two notes.

There are three characteristics of an interval:

• The distance of the interval
• The type of interval (the interval quality)
• Is the interval harmonic or melodic?

Interval Distance

The smallest possible interval (in western music anyway) is a semitone, or in the US it’s called a half step. A semitone is the very next higher or lower note.

The word ‘semi’ means half (it’s the same semi that we get semiquaver from which is ‘half’ of a quaver) so we could think of the word semitone as ‘half a tone’.

A tone or whole step, therefore, is an interval of two semitones.

Interval Number

We describe intervals using numbers depending on how many letter names of the musical alphabet there are between the two notes.

e.g. if we look at the notes C and E they are three letter notes apart and so this interval is a 3^rd. C to Eb is also a 3^rd.

Interval Quality

perfect

To be a perfect interval the upper note has to be in the major scale of the low note

There are three intervals that are what we call perfect intervals: perfect 4^th, perfect 5^th, perfect 8ve

For example C to F# is a 4^th but is not a perfect 4^th as F# is not in C major scale

major

• There are four intervals that are called major intervals:
  • major 2^nd, major 3^rd, major 6^th, and major 7^th
• If the upper note of an interval is in the major scale of the lower note (and it’s not a 4^th, 5^th or 8ve) then it will be a major interval.

• augmented
  • An interval becomes augmented when we extend a major or perfect interval by one semitone (half step) without changing the letter name.
  • For example, given a major 2^nd like F to G, change the G to G# to make an augmented 2^nd.
  • For example, given a perfect 5^th like F to C, change the C to C# to make an augmented 5^th.

• minor
  • Any major interval made smaller by one semitone is a minor interval
  • For example, if we took C to E which is a major 3^rd and flattened the E to make it an Eb, it now becomes a minor 3^rd.
  • Because there are only four major intervals there are also only four minor intervals:
  • minor 2^nd, minor 3^rd, minor 6^th, minor 7^th

• diminished
  • Flatten any of the three perfect intervals (the 4^th, 5^th or 8ve) or any minor interval (minor 2^nd, minor 3^rd, minor 6^th, or minor 7^th) by a semitone, to make a diminished interval.
  • For example, given A and D which is a perfect 4^th, flatten the D to Db to make it a diminished 4^th.
  • For example, given E and D which is a minor 7^th, flatten D to Db to make it a diminished 7^th.

Interval Chart

Semitones	Interval	Abbreviation	Example
0	Unison	PP or P1	C – C
1	Minor 2nd	m2	C – Db
2	Major 2nd	M2	C – D
3	Augmented 2nd	A2	C – D#
3	Minor 3rd	m3	C – Eb
4	Major 3rd	M3	C – E
4	Diminished 4th	D4	C – Fb
5	Perfect 4th	P4	C – F
6	Augmented 4th	A4	C – F#
6	Diminished 5th	D5	C – Gb
7	Perfect 5th	P5	C – G
8	Augmented 5th	A5	C – G#
8	Minor 6th	m6	C – Ab
9	Major 6th	M6	C – A
10	Minor 7th	m7	C – Bb
11	Major 7th	M7	C – B
12	Perfect 8ve	P8	C – C

Compound Intervals

A compound interval is any musical interval that is larger than an octave as opposed a simple interval which spans less than an octave.

For intervals larger than an octave, just repeat the simple interval adding '7'.

For example, C to E is a major 3d and C to E an octave above is a major 10^th.

Harmonic Intervals

Harmonic intervals are how we describe two notes that are played, at the same time.

Melodic Intervals

The opposite of a harmonic interval is a melodic interval which is where the two notes are played one after the other.

Scale

Music Scales Beginners Guide

A scale is a group of notes that are arranged by ascending or descending order of pitch.

There are many different musical scales.

Each scale uses a different formula of intervals and has a completely different sound and feel. Some sound happy, some sound mysterious and some sound sad or melancholy.

Scale Degree

Each notes in a scale are know as degrees. A scale has 7 degrees named as follows:

• 1^st degree: the tonic
• 2^nd degree: the supertonic (above the tonic)
• 3^rd degree: the mediant (middle of a triad chord, a 3^rd above the tonic)
• 4^th degree: the subdominant (a 5^th below the tonic)
• 5^th degree: the dominant (a 5^th above the tonic)
• 6^th degree: the submediant (a 3^rd below the tonic)
• 7^th degree: the leading note (or leading tone)

The natural minor scale is different: the 7^th degree of the scale is an interval of a tone (whole step) below the tonic instead of a semitone (half step) like the leading note. For this reason a flattened 7^th note is called the subtonic.

Triad Chord

When building a triad chord we use three notes: the 1^st, 3^rd and 5^th degrees of the scale.

Major Scale

Major scales are defined by their combination of semitones and tones (whole steps and half steps):

Tone – Tone – Semitone – Tone – Tone – Tone – Semitone

Or in whole steps and half steps it would be:

Whole – Whole – Half – Whole – Whole – Whole – Half

Minor Scales

Minor scales also have seven notes like the major scale but they’re defined by having a flattened third. This means that the third note is lowered by one semitone or half step.

Unlike the major scales where there is only variation, there are three different minor scales: natural, harmonic, and melodic.

The Natural Minor

A natural minor scale uses this formula of tones and semitones (whole steps and half steps).

T – S – T – T – S – T – T

Or in whole steps and half steps it would be:

W – H – W – W – H – W – W

The Harmonic Minor

Harmonic minors use this combination of tones and semitones:

T – S – T – T – S – T1⁄2 – S

Or in whole steps and half steps it would be:

W – H – W – W – H – W1⁄2 – H

Note that harmonic minors have an interval that is a tone and a half or three semitones.

The harmonic minor is very similar to the natural minor. The only difference is that the 7^th degree of the scale is one semitone higher.

The Melodic Minor

Melodic minor scales are quite different from natural and harmonic minors as they use different notes when ascending (going up) and descending (going down).

Ascending melodic minors use this combination of tones and semitones:

T – S – T – T – T – T – S

Or in whole steps and half steps:

W – H – W – W – W – W – H

But on the way down they use this combination (from the top down):

T – T – S – T – T – S – T

Or in whole steps and half steps

W – W – H – W – W – H – W

A melodic minor ascending is:

When descending the 6^th and 7^th notes are lowered by one semitone.

Diatonic vs. Chromatic Scales

The Major Scale and Minor Scales are diatonic scales. A diatonic scale is a type of music scale with seven notes (also called a heptonic scale).

A diatonic scale use all seven pitch letter names (A, B, C, D etc) in sequence without skipping any.

Whole Tone Scale

Pentatonic Scale

Modes

Learn Modes=

Modes, which are sometimes called the church modes, are a series of seven musical scales each with their own unique qualities and sound.

These seven scales are all types of diatonic scale which means they have seven notes and have two intervals that are semitones (half steps) and five intervals that are tones (whole steps).

There are seven types of modes:

• Ionian mode
• Dorian mode
• Phrygian mode
• Lydian mode
• Mixolydian mode
• Aeolian mode
• Locrian mode

We can also categories these seven modes into two types, major modes and minor modes.

Major modes are major because the third note in their scale is a major 3^rd above the tonic and the minor modes are minor as the third note in their scale is a minor third above the tonic.

The three major modes are: Ionian, Lydian and Mixolydian and the four minor modes are: Dorian, Phrygian, Aeolian and Locrian.

Each mode is formed starting at a different point in the major scale formula:

Ionian is the regular major scale.

Aeolian is the natural minor scale.