Fugue Definition

A fugue is a contrapuntal composition for a number of separate parts or voices.

Usually a composer chooses to describe or define a fugue they have composed according to the number of parts it is written for. e.g. “a fugue in 4 parts”, “a fugue in 3 voices”.
Each part/voices enters in imitation of each other.

We are going to look at the basic structure of a fugue through a worked example.

The Basic Structure of a Fugue

The Exposition

A fugue starts with the 1st voice/part playing a melody/phrase called the Subject.
The subject is played by the 1st voice in the tonic key.
Here is the subject I have written for my worked example of a fugue:
Fugue Example Subject sheet music extract

Fugue Example Subject

The 2nd voice then enters playing the “answer”.
The answer is a transposed version of the subject (usually in the dominant key).
Here is my fugue answer (orange shaded notes):
Fugue Example Answer sheet music extract
Fugue Example Answer

The 3rd voice then enters playing the subject again.
It is in the tonic key, but often an octave higher or lower than the 1st voice.
Here is my subject being played in the 3rd voice (blue shaded notes) an octave higher than it was played by the 1st voice:
Fugue Example Repeated Subject sheet music example
Fugue Example Repeated Subject

Note: If I was writing a 4th voice/part for my fugue then the 4th voice would enter at this point playing the answer.

This whole section of music is called The Exposition.
Have a look/listen to my fugue exposition:
Fugue Example Exposition sheet music extract

Fugue Example Exposition

Key Changes in the Exposition

Contrasting keys play a vital role in the composition of a fugue.
In the Exposition the subject 1st appears in the tonic key.

The 2nd voice plays the “answer” in dominant key (a 5th higher or a 4th lower) – this transposed line in the 2nd voice is called the answer.
If it is an exact transposition of the subject then it is called a “real answer”.
However, if it is altered to fit the new key then it is a ”tonal answer”.
You can see from my fugue example that the answer (orange notes) has been changed and so it is a tonal answer.

The Subject is repeated in the entry of the 3rd voice (usually in the tonic, but at a different octave) and is “answered” by the 4th voice (if there is one), again in the dominant key.

Diagram of key changes in fugue exposition
When all the voices have entered this signals the end of the Exposition


A Countersubject often appears in the Exposition (and also later in the fugue).
A countersubject acts like an accompaniment to the Subject and Answer.
So, the voice/part which has just played the Subject will go on to play the Countersubject whilst the next voice is playing the answer.
Here is the countersubject (highlighted yellow) at the start of my fugue:
Fugue Example Countersubject sheet music extract

Fugue Example Countersubject

After the Exposition there comes an Episode.

The Episodes

An episode is a connecting passage of music in a fugue and is usually made up of a development of the music that has already been heard in the Exposition.
Here is the 1st episode of my fugue example which comes directly after the exposition:
Fugue Example Episode sheet music

Fugue Example Episode

I have used musical ideas from the exposition, including rhythms and short melodic phrases in my 1st espisode.

After the Episode in a fugue there is usually another entry (or entries) of the Subject.
I have included this in my fugue example, but in the dominant key:
Fugue Example Second Subject Entries Sheet Music

These new entries of the subject are followed by another Episode (second episode in Green below).
Fugue Example Second Episode sheet music extract
This alternating of Subject entries and Episodes can continue in a fugue for as long as the composer wants.

Diagram of Basic structure of a fugue

Key Changes in Fugue Episodes

The Episodes in a fugue are often used by the composer to modulate to different keys.
This brings added variety to the entries of the Subject later on in the fugue.

Have a look/listen to my 2nd episode below.
Can you see/hear the key changes? (The presence of accidentals give a big clue when spotting key changes)
Fugue Example Second Episode sheet music

Fugue Example Second Episode

Other Features of Fugues


Stretto literally means “drawn together”.
In the context of a fugue it describes a situation where each voice enters before the previous voice has finished its subject.
This overlapping technique is used by composers to increase the emotional tension of the piece.
I have decided to use stretto after my 2nd episode to increase the tension as we move towards the end of my fugue:
Fugue Example Stretto sheet music

Fugue Example Stretto

You can see/hear how the different voices enter “early” before the previous voice has finished playing the subject.
Here is a visual diagram of stretto in a fugue:

Diagram of use of stretto in a fugue

Can you see how each voices enters before the previous voice has finished playing its subject?

The Coda

The Coda in a fugue is a final section of music that often includes stretto.
Its primary aim is to move the piece to an appropriate conclusion.
In my coda I have used stretto to continue to increase the drama as the fugue ends:
Fugue Example Coda sheet music

Fugue Example Coda

The Completed Fugue Example

Here is my completed worked fugue example.
I have labelled the main sections and have highlighted the 3 voices in different colours so that you can see how they work together.
Fugue Example Composed by Ben Dunnett
Fugue By Ben Dunnett

Hopefully this worked example will help you understand the basic meaning of what a fugue is and how it is composed.
However, it is very important that you listen to some famous examples of fugues.

Famous Examples of Fugues

There are many examples of fugues.
Arguably the most famous composer of fugues is Johann Sebastian Bach.
Have a look/listen to this excellent video which shows the Art of Fugue by Bach:

Other Forms of Fugues

There are various other forms of fugues that you may come across.

Double Fugues

You will sometimes come across Double Fugues. These can be seen in 2 forms:

  1. 2 subjects appear together at the start of the piece
  2. A subject is introduced at the start of the piece and answered in the usual way. A second subject is then introduced and also answered. The 2 subjects are then combined at a later point in the piece.

Example of a double fugue – J.S. Bach – Prelude and double fugue no. 18 in G sharp minor BMV 887 (WTC II)

Other Useful fugal forms
  • Fughetta – this is a shortened fugue
  • Fugato – this is a passage of music in fugal style, but not in itself an actual fugue.
  • Accompanied Fugue – these are sometimes found in oratorio movements where there is a free instrumental part accompanying the singing.