Augmentation and diminution are two musical techniques used by composers to develop/vary a melody.
They are great tools for you to be able to understand and use as a composer.
Let’s have a look at each technique in turn.
Augmentation is the lengthening of the time values of the notes of a melody.
It is described as “a device which adds dignity and impressiveness”!! (Oxford Dictionary of Music, Kennedy, M.)
Composers often use it as a technique to bring “majesty” or “climax” to the end of a section or piece.
Have a look/listen to this example of augmentation:
Can you see how the opening melody uses 6 quarter notes (crotchets) followed by a half note (minim)?
The same pitches are then repeated, but this time the lengths of the notes are doubled to be 6 half notes (minims) and one whole note (semibreve).
This lengthening of the note lengths is called rhythmic augmentation.
Diminution is the shortening of the time values of the notes of a melody.
This technique often brings a heightened sense of “urgency” or “tension” to the music.
Have a look/listen to this example of diminution:
In this example the opening melody again uses 6 quarter notes (crotchets) followed by a half note (minim).
The same pitches are then repeated, but this time the lengths of the notes are halved to be 6 eighth notes (quavers) and one quarter note (crotchet).
The melody is repeated again and the notes are halved in length again to be 6 sixteenth notes (semiquavers) and one eighth note (quaver).
This is then repeated again to produce 6 thirty second notes (demisemiquavers) and one sixteenth note (semiquaver).
This process of shortening the note lengths is called rhythmic diminution.
Intervallic Augmentation and Diminution
The most common form of augmentation and diminution is the lengthening and shortening of the note lengths.
However, you may also see composers use a technique that augments the size of the intervals of the melody.
Have a look/listen to the following example:
The melody has an interval of a perfect 5th between the C and the G in the 1st bar.
In the repeat of the melody, the interval has been increased to a major 10th (between the C and the E an octave higher).
Each of the successive intervals are also extended (in the opening melody the intervals are a major second, whilst in the repeat of the melody they have increased a minor 3rd).
This process is called intervallic augmentation.
In intervallic diminution the process is reversed:
In the example above, the opening interval of a perfect 5th has been reduced to a major 3rd in the repeat.
The next interval of a major 2nd has been reduced to a minor 2nd in the repeat.
The techniques of intervallic augmentation and diminution are really effective means of bringing variety and development to your melodic ideas.
Composing Using Augmentation and Diminution
Rhythmic augmentation and diminution can be great techniques for bringing increased emotion and variety to your compositions.
Rhythmic augmentation often brings a sense of increased “majesty” and “climax”.
Rhythmic diminution often brings increased “urgency” and “tension”.
Intervallic augmentation and diminution can be used to bring variety and development to melodies.
My advice is to write a short melody and then try experimenting with these techniques.
See what effect the different techniques have on your melody. Good luck!