Synthesis Series: What is Granular Synthesis?

February 18, 2024
5 mins read
A visual depcition of granular synthesis

You may have seen the term ‘granular’ here and there and maybe wondered what it is and how it works. Kickstarting this synthesizer series, let’s dive into the more unusual yet awesome one of the bunch.

In the world of sound design, the aim of creating super unique sounds is a primary focus. Manipulating samples to create a sound nothing like the original is exciting. There are plenty of methods of sampling; however, granular synthesis is a commendable method that results in both lush pad textures and ultra-glitchy soundworlds.

Synthesizers: What are they?

First, let’s establish what a synthesizer is.

A synthesizer, also known as a synth, is a type of electronic musical instrument that generates sounds through various components, including oscillators, modulators, and filters. By adjusting these components, synthesizers can create a wide range of sounds, tones, and timbres, some of which can emulate real-life instruments or sound effects.

Synthesizers usually use a keyboard interface, which makes them suitable for playing melodies, but they can also come in the form of modular synths, drum machines, or software synths. Furthermore, synthesizers can either be analog or digital: analog uses circuits, whereas digital uses Digital Signal Processing (DSP) to shape sounds.

The Basis of Granular Synthesis

Granular synthesis works on the basis of chopping up an audio sample into tiny segments called grains. These grains can range from 1 to 200 milliseconds in length. Granular synthesis allows us to take control of the audio grains, and each grain can be manipulated, including the overall arrangement of the grains.

When the grain samples are in order, this is called a graintable. However, the grains don’t necessarily have to be played in order.

We can take the tiniest segment of audio and have the granulator playback a stream of loops. Here, we can make pads as well as glitchy instruments just from a single audio segment.

Of course, when you are looping grains, as they are very small snippets of audio, it may sound very sparse. Upon manipulating these grains, a smoothing effect is applied, which uses cross-fades to blend from one grain to the next for a more natural sound.

When compared with traditional synthesis methods, which involve generating a waveform (sine, square, etc.) and shaping it using Low-Frequency Oscillation (LFO), filters, and more, granular uses pre-existing audio/samples to create new sounds.

Why Use Granular Synthesis?

When chopping up samples, it can create some really surprising textures that are perfect for achieving that experimental electronic sound. From atmospheric pads to glitchy percussion, granular synthesis can create the most unique sounds to elevate your sound design even further.

Granular synthesis has its main uses, including time stretching, pitch shifting, and adding interest to texture.

Time stretching is achieved by manipulating the playback speed of the grains without affecting the pitch of the sample. It works similarly for pitch shifting, where we can manipulate the pitch of the grain without affecting the speed. This technique is actually found in Ableton Live when the Warp mode is activated on a sample. It uses granular synthesis to take a grain from the sample and loop it over and over again to make up for the space when it’s being time-stretched.

Grains don’t have to playback in chronological order; they can be scrambled or reversed, which can result in some pretty interesting textures. In combination with changing the speed, pitch, and durations, in addition to other effects like reverb and filters, you can create something with extreme fuzziness or mangling of the original sample. 

Granular Components

There’s a variety of parameters that make up the granular synthesiser, all of which have specific roles that contribute to the synthesis in place. 

  • Grain Size – Controls the duration of the grains; the shorter the grain, the glitchier. The longer the grain, the more sustained. 
  • Grain Density – Controls the amount of grains triggered per second. The higher the density, the more complex and ‘dense’ the sound will be. The lower the density, the more transparent and sparse the sound. 
  • Pitch – Adjusts the pitch of the grains. You can transpose the entire sample or a selection of grains for more variation.
  • Position – Determines the position of the grains within the sample. You can set a specific starting point within the sample for the synth to start the granular process. By scanning through the sample and finding a point of interest, you can adjust the position parameter to only process in those certain points. 
  • Envelope – Controls the amplitude of each grain, otherwise known as the fades. This is also known as ‘smoothing’ or ‘grain shape’. Having smoother envelope settings results in more consistency, but having shorter envelopes results in more abrupt fades. 
  • LFO Modulation – Most synthesizers offer modulation parameters like LFO to add movement to your sound. An LFO outputs a signal in a particular waveform (e.g., sine, square, etc.) and can be assigned to another parameter (e.g., grain size, position, filter, etc.) so that they can change over time. 
  • Effects – Effects such as reverb and delay can be found in granulators to shape the sound further.

Ambient and Glitchy Textures

Granulators are commonly used to create both ambient and glitchy textures, primarily due to the grain size and smoothing parameters, in combination with other parameters.

When we think of ambient textures, drones come to mind. Drones are sustained sounds that may evolve over time or remain continuous and serve as the foundation of ambient music. We can use the granulator to create an ambient drone from a sound that doesn’t necessarily sustain for a long period.

Ableton Live Suite features an exceptional Granulator created by Robert Henke (aka Monolake), which is a powerful tool for crafting distinctive sounds from virtually anything. In the video, he showcases how this specific granulator can transform a single strike of glass into an extraordinary ambient pad.

Additionally, it is possible to produce glitchy sounds. This can be achieved by randomizing the position of the grains and decreasing the length of the grains. By increasing the randomness, we can achieve a greater variety of textures playing back through the sample. Coupled with shorter grain sizes, this will lead to a glitch effect. This technique is especially effective for samples with more noticeable transients.

Try it yourself!

The best way to figure out how granulators work is to try it yourself simply. Speaking from experience, when my teacher showed me the free granulator program Cecilia 5, I had very little idea of what granular synthesis was! I knew that I wanted to make a drone from a single strike of a piano note. I increased both the number of grains and the grain duration and altered the time output for a long, sustained note, and I eventually got there! 

Apart from Cecilia 5, a free plug-in bundle called Soundhack includes a Bubbler Plug-in, which is based on the granular synthesis. It’s a fantastic plug-in that results in incredible and authentic sounds. 

If you are a Logic Pro user, Alchemy has a built-in granulator that allows you to drop in your own samples and adjust to your needs.

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Zoe Sones

Zoe Sones, a UK-based composer, specializes in acoustic contemporary classical and ambient electronic music. She explores various textures and timbres from instruments and nature, creating haunting electronic drones and harmonically rich chords.