Granular Synthesis
Creating Grains
Grains can be made by cutting sounds into very small pieces.
These small pieces can then be reassembled in a randomized order to create a granular cloud .
Grain can also be made from very short bursts of noise or from electronic tones.
Properties of Grains
The main properties of a grain can be described in:
- Duration – how long is the grain?
- Envelope – what is the shape of the grain over time?
- Stamp – sometimes called “grain shape”, this is inherited from the properties of the source sound.
Each of these characteristics will affect the quality of the granular cloud.
Duration
The length of the grain may vary from ten-milliseconds (10ms) up to a few seconds.
Long grains will retain a lot of the character of the original sound, while shorter grains will begin to lose this character.
The more recognizable individual grains become.
Vary Grain Length
At the beginning of this clip, the grain is very short. Slowly the grain duration increases, revealing more of the original source.
Composition Tip
- Short durations can be used to create new textures.
- Long grain durations can be used to extend and enhance existing sounds, while still retaining their original qualities.
Envelope
The shape of the grain over time will affect how they combine and merge themselves together.
Envelopes allow grains to merge together. The type of envelope chosen will affect the way in which the grain will be used.
Vary Grain Envelope
At the beginning of this example, a very harsh envelope is used with short attack and release. By the end of the file, the envelope has been modified to have a very smooth and (relatively) long attack and release.
Timbre
The timbre of the grain (which some people call the grain shape) is affected by the original source material from which the grain was cut.
Different source materials will create different grain textures.
Variation in Grain Stamp – Source Material
In this clip, the grain parameters of duration and the envelope are not changed. It is the source material that is changed. We hear three different sources:
3. Human voice and laughter
Important
Remember, the duration and envelope of the grain will also affect the final result of the granular cloud.
Combining Grains
When we begin to combine grains into ‘clouds’, the way in which the grains relate to one another greatly affects the quality of the granular cloud that is made.
We need to be able to describe the relationship between the grains.
We can talk of the:
-
- Spacing – how big is the gap between grains?
- Density – How Many seeds are there in one spot
Dense Granular Cloud
This sound has a high density of sound grains.
Sparse Granular Cloud
This example has a low density of sound grains.
From Grains to Sound Masses
Grains can be brought together in two different ways in order to create ‘sound masses’.
The types of grains used in which they are combined, will affect the characteristics of the final sound.
Blocks of Sound
They can merge to form larger sounding objects, their own character in the new object.
There is little space between grains and their envelopes overlap to create a seamless sound.
Properties:
- Low spacing
- High density
Clouds of Sound
They can be grouped together, still retaining their individual grain characteristic, in a granular cloud .
The grains form a cloud of sound, in which individual grains flock together.
Properties:
- Higher levels of spacing
- Lower levels of density
Composition Tip
Try using blocks and clouds of sounds within your composition. Can you imagine how they could be combined?
- Perhaps a block of sound is shatter into a granular cloud,
- OR has a granular cloud might merge to form a block of sound?
Be creative!
Fact
The granulation process is also used within time-stretching algorithms. It allows us to time-stretching a sound without changing the pitch.
It works by granulating the original sound and then looping the grains. This extends the sounds without changing the pitch.
