Grains can be made by cutting sounds into very small pieces.
These small pieces can then be reassembled in a randomised order to create a granular cloud.
Grains 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 terms of:
- Duration – how long is the grain?
- Envelope – what is the shape of the grain over time?
- Timbre – 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.
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 longer the duration of each grain, the more recognisable individual grains become.
At the beginning of this clip, the grain duration is very short. Slowly the grain duration increases, revealing more of the original source.
- 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.
The shape of the grain over time will affect they way in which individual grains combine and merge themselves together.
Envelopes allow grains to merge together. The type of envelope chosen will affect the way in which the grains combine and will affect how much of the original timbre of the sound source we hear.
At the beginning of this example, a very harsh envelop 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.
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.
In this clip, the grain parameters of duration and envelope are not changed. It is the source material that is changed. We hear three different sources:
Remember, the duration and envelope of the grains will also affect the final resulting timbre of the granular cloud.
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 grains are there in one place (density is discussed in more detail here)?
This sound has a high density of sound grains.
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 and they way in which they are combined, will affect the characteristics of the final sound.
They can merge to form larger sounding objects, surrendering their individual character into the new object.
There is little or no space between the grains and their envelopes overlap to create a seamless sound.
- Low spacing
- High density
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 but are still heard as distinct from one another.
- Higher levels of spacing
- Lower levels of density
Try using blocks and clouds of sounds within your composition. Can you imagine how they might be combined?
- Perhaps a block of sound might shatter into a granular cloud,
- OR a granular cloud might merge to form a block of sound?
The granulation process is also used within time-stretching algorithms. It allows us to time-stretch 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.