Granular Synthesis

What Is Granular Synthesis?

In short, granular synthesis is a form of synthesis that breaks a sound into tiny particles ( grains ) and further reorganizes and redistributes them to create a new sound. Undoubtedly, it is a powerful method of sound manipulation that involves control over pitch, speed, and formant characteristics that are independent of one another. In other words, it is a good grouping process operating on the micro-sound timescale.  

The History Of Granular Synthesis

It all started in 1946 when physicist Dennis Gabor published his work about applying quantum physics methods to the sound signal. With this work, he developed a system that uses a grain system to reproduce a sound. In later years, Greek-French composer and musical theorist Iannis Xenakis got in touch with Gabor's work. Soon after, he created a musical application based on that principle. His first works involved granular synthesis made by splicing magnetic tape into tiny segments, rearranging those segments, and taping the new string of the segments together. Inspired by Xenakis's works, Curtis Roads began experimenting with this idea on a computer shortly after. He was the first to implement granular sound processing in the digital domain. In the mid-1980s, a Canadian composer named Barry Truax began developing a way to create a granular synthesis in real-time. Since then, granular synthesis has become available to many musicians.  

Time Stretching & Time Compression

They are fundamental to this synthesis, and creating more or less dense clouds of granular audio particles is another aspect. The basic parameters that can be found in most of the grain generators are :  

1. Grain Position

Grain position determines the point in the audio file at which grains are created. When grain Speed is set to "0, "the audio is "frozen "at that position; with positive speed values, the audio stream plays forward, and negative values reverse the audio. Furthermore, LFO or an envelope can modulate Grain Position. In this case, the "Speed" value is usually set to 0 so that only the modulator determines the direction and speed of the grain stream.  

2. Grain Speed

As mentioned above, this parameter determines the speed at which the sample "play head" runs through the sample. Some granulators also use positive/negative speed values to determine the direction of the grain stream (forwards/backward).  

3. Grain length

With sizes below 50ms, the grain stream turns into noise without a distinct pitch. Very short grain sizes below 10ms, in combination with some randomization of grain position, create more white-noise-like effects. Also, there are ways of achieving sounds that remind of ring modulation without randomization. If the grain duration is longer than the intervals between the creation of each grain, it will create a sustained sound. If it is smaller, the sound gets perforated/fragmented.  

4. Grain density

Grain density determines the number of created grains over a given period of time. Therefore, the higher the density, the more continuous the sound will become.  

5. Grain shape

Most granulators offer a variety of shapes applied to the amplitude of each grain. The most common shapes are Hann, Hamming, Triangle, Sine, Rectangular, Blackman Harris, and Welsh. Generally speaking, smoother waveforms with round curves create more organic-sounding results, while shapes with more right-angled forms create more edgy and distorted tones.  

6. Grain pitch

This parameter determines the pitch of each grain. Additionally, Grain Pitch can be randomized within a given range, making for some very interesting chaotic grain pitch clouds. They can also be pitch-quantized to specific scales like pentatonic, major, minor, diminished, Dorian, etc., producing tonal grain clouds.  

Additional Resource & Source Texts

• Create Complex Sound Textures with Grain Delay
• Spicing up Your Synth Pads
• Digital Sampling