6.8 Augmented fourth, diminished and augmented fifth
Category: Harmony  Tags: Intervals, Ear training: intervals 
Theory
In Chapter 3.6 Perfect fifth you’ve learned what a perfect fifth is and in Chapter 4.8 Perfect fourth and octave what a perfect fourth is. In this chapter, you will learn about the augmented fourth, diminished and augmented fifth. In the videos and examples I show how to make augmented fourths, diminished and augmented fifths. You learn to recognize augmented fourths, diminished and augmented fifths and you are goning to make them yourself in the exercises. You will also learn to distinguish perfect and augmented fourths and perfect fifths by ear.
1. Augmented fourth
The fourth from F to B is called an augmented fourth and is made up of six half steps (three whole steps).
An augmented fourth is made by raising the highest tone of a perfect fourth, or by lowering the lowest tone of a perfect fourth.
The augmented fourth F B .
Examples
How do you raise a perfect fourth?
The augmented fourth is a somewhat odd interval. This can occur in different forms. From beautiful to "devilish", or false. There is a story that a certain type of fourth was banned in the Middle Ages, being associated with the devil. However, there is no evidence for this story. This type of fourth is the only interval that has its own name: the tritone. In etude no. 3 by Chopin, you can hear a lot of tritones:
Video
Examples
Which tones do you get if you make augmented fourths on the natural notes?
2. Diminished fifth
The fifth from B to F is called a diminished fifth and is made up of six half steps (three whole steps).
A diminished fifth is made by lowering the highest tone of a perfect fifth, or by raising the lowest tone of a perfect fifth.
The diminished fifth B F sounds the same as an augmented fourth.
Examples
How do you lower a perfect fifth?
Video
Examples
Which tones do you get if you make diminished fifths on the natural notes?
3. Augmented fifth
The fifth from C to G# is called an augmented fifth and is made up of eight half steps (four whole steps).
An augmented fifth is made by raising the highest tone of a perfect fifth, or by lowering the lowest tone of a perfect fifth.
The augmented fifth C G# sounds the same as a minor sixth.
Examples
How do you raise a perfect fifth?
The augmented fifth is found in the harmonic and melodic minor scale.
Examples
Which tones do you get if you make augmented fifths on the natural notes?
4. Inversion of an augmented fourth
By inverting the augmented fourth F B we get B F , this is a diminished fifth.
The inversion of an augmented fourth is a diminished fifth.
Examples
5. Practise
Harmony exercise 6a: practise recognizing perfect, diminished and augmented fourth and fifth from musical notation.
Harmony exercise 6b: practise making perfect, diminished and augmented fourth and fifth on the natural notes.
Harmony exercise 6c: practise making perfect, diminished and augmented fourth and fifth on all notes.
6. Ear training
Practise
Ear Training exercise 6f: practise distinguishing the difference between perfect and augmented fourths and perfect fifths by ear.
Example question
Which interval do you hear?
Choise 1: perfect fourth
Choise 2: augmented fourth
Choise 3: perfect fifth
Practical steps
Sing the interval being played to train your inner hearing abilties. Decide which interval is being played.
Answer: augmented fourth.
Summary
Augmented fourth, diminished and augmented fifth
 A raised perfect fourth is called an augmented fourth
 A lowered perfect fifth is called a diminished fifth
 A raised perfect fifth is called an augmented fifth

Practise
Harmony exercise 6a: practise recognizing perfect, diminished and augmented fourth and fifth from musical notation.
Harmony exercise 6b: practise making perfect, diminished and augmented fourth and fifth on the natural notes.
Harmony exercise 6c: practise making perfect, diminished and augmented fourth and fifth on all notes.