Granular Synthesis Explained

What is Granular SynthesisWith wavetable, subtractive, additive and other forms of synthesis, it’s easy to see how some engineers can dedicate their lives to synthesizers alone.

Each of these worlds comes with boundless possibilities. So in this post, we will be covering granular synthesis.

This type of oscillation is relatively new and has unique traits to set it apart from other methods.

Let’s break everything down so that you can start incorporating this powerful tool into your tracks.

What is Audio Synthesis?

Before diving into the modern form of granular synthesis, let’s briefly go over what “audio synthesis” means, and where the general term is applicable.

Audio or Sound Synthesis is defined by any method used to create sound using electronic signals/impulses as opposed to traditional instruments.

Synthesizers are devices that create these signals. The waveforms (Sine, Square, Triangle, Sawtooth, etc.) are produced from Oscillators within the synthesizer.

Audio Synthesis can be broken down into a couple of subgroupings depending on how the signals are processed within the synthesizer.

Common subgroupings include hybrid, FM or Frequency Modulation, AM, subtractive, additive, wavetable, vector, phase distortion, and granular, which we will be decoding today.

If you want a clearer understanding audio synthesis in general, check out our really fun post on the topic.

What is Granular Synthesis?

Granular synthesis is built off of the principle of grains, hence the name. A grain is a subdivided portion of a sound waveform typically anywhere from 1 to 100 milliseconds in length.

High and Low Frequency Grains
High and Low Frequency Grains

An easy way to picture grains is to think about traditional sampling. If one were to take a vocal track and chop it evenly into multiple sections, each of these sections could theoretically be considered a grain, but on a much larger scale.

In simple terms, grains are minuscule, proportionate components that make up a larger signal. The process of using granular synthesis is sometimes referred to as granulation.

Grains can be altered by the duration of the particle, frequency, and intensity. Moreover, they can be broken down into two main parts: The audio signal itself, and the envelope.

The envelopes can be manipulated individually as well to produce an even more intricate sound.

They can be played at various speeds, levels, or frequencies, and can be layered on top of one another. In granular synthesis, they are altered in 4 main ways:

  • Layering– Similar grains are layered on top of one another
  • Extraction– Particular grains are removed from a signal
  • Looping– Certain grains are copied and repeated in a sequence
  • Reordering– Grains are rearranged within a signal

Granular synthesis encompasses any type of audio editing that is centered around the altering of grains. It can be broken down into two main subcategories, Asynchronous and Synchronous.

Don’t worry. These words, although somewhat intimidating, are fairly simple concepts to grasp:

Synchronous– This method does not involve any reordering and is the more simple method as here, the grains are evenly spaced in relation to one another.

Simply put, synchronous granular synthesis involves altering parameters such as amplitude, texture, and pitch. A common example of synchronous synthesis is pitch or time warping.

syncShronous granular synthesis
Synchronous granular synthesis

Asynchronous– Here, the grains can be reordered in an infinite amount of ways. The parameters remain the same, however, grains do not have the constraint of timing or being linear. So in addition to amplitude, texture, and pitch, there may be an algorithmic function within a synthesizer, the randomize the order of grains.

Asynchronous granular synthesis is mainly used to create unique textures and atmospheric sound “clouds”.

Asynchronous granular synthesis
Asynchronous granular synthesis

These two subcategories are each extreme and on the opposite ends of the granular spectrum. For instance, there is such a thing as quasi-synchronous granular synthesis, which involves evenly spaced out grains with unpredictable delay gaps lying in between the two main types.

More niche forms exist as well such as Glissando, Wavelet, and Pulsar synthesis. Each has its own set of strict guidelines but is more or less focused around the altering of grains.

A Brief History

Granular synthesis as a method is very modern. In fact, it wasn’t properly streamlined until 1986. Sound engineers had difficulty configuring signals where the pitch and speed were mutually exclusive, probably since back then, most recordings were created on physical tape.

The gap between emerging technology and brand new methodology further slowed the process. Autotune, a popular voice software that utilizes granular synthesis, was first commercially used in 1998 by Cher in her hit, “Believe”. Since then, it has become a staple among novices and professionals alike. Here’s a closer look into the evolution of granular processing.

The Evolution of Granular Synthesis

  • In 1946, Dennis Gabor published a body of work theorizing a correlation between quantum physics and sound signal in 1946. His findings focused mainly on the principle of smaller elements producing a whole, rather than one linear structure. Gabor was the first to insinuate that sound could be mathematically subdivided into infinitely smaller sections.
  • Composer Lannis Xenakis, who later picked up this work, reached out to Gabor to further his understanding. Soon, Xenakis found himself splicing physical tape, removing/adding sections, and reconfiguring/testing the adjusted versions to confirm his assertions. By completing this successfully, Xenakis is credited as the first to utilize granular synthesis.
  • An engineer named Curtis Roads studied Xenakis’s and Gabor’s contributions and digitized the process. Roads was the first to implement granular synthesis through a digital medium. Although this method was technically functional, the processing took far too long to produce any real-time results. Granular synthesis at this time was not publicly accessible, for most computers couldn’t handle the data influx anyway.
  • In 1986, Barry Truax made it possible for granular synthesis to be used realistically within a DAW. He realized his body of work, “Riverrun” while using an early version of musical composition software, called POD or PODX at Simon Fraser University. This was the first time that granular synthesis was able to be simultaneously seen and created in real time.
See/Hear “Riverrun” Below

Thus, granular synthesis was finally streamlined and ready for everyday use!

The Science Behind it

One of the characteristics that make granular synthesis so special is its ability to alter the timing of a clip without affecting the pitch, sometimes coined as warping. If you’ve ever sped up/slowed down vinyl on a record player, you’ll notice that the speed changes, but the pitch is also altered. Granular synthesis is able to separate these conditions completely by playing tricks on our hearing.

The way that this works is by the synthesizer looping or removing certain grains in order to trick the human ear into perceiving a faster or slower sound.

In cases involving slowing down a sound, certain grains will be duplicated and looped, and as a result, the track will be longer without changing pitch. For speeding up a sound, non-pivotal grains are removed so that the ear cannot detect a significant change, but in turn, perceives a faster signal.

This may be partially attributed to the phonemic restoration effect, which is the property of hearing in which our brain automatically fills in sound gaps with predictive noises. Our brain is able to fill in the gaps where grains are added/removed, making a signal appear unaltered.

Basically, audio signals are either recycled or removed to lengthen/shorten a preexisting signal. The changes to the grains are mainly imperceptible to the human ear, so it appears to be a cohesive, linear new signal rather than a reformation of the original sound.

Common Applications

One can use granular synthesis to create a bevy of distinct sounds. Here are some of the most common uses for this form of modulation.

Soundscapes or Sound “Clouds”

At a low playback speed, samples processed with granular synthesis produce very ethereal, atmospheric sounds, very difficult to replicate with other forms of processing. With high playback speeds, granular synthesis produces rare high pitched sounds with interesting timbre. These sounds, commonly referred to as audio “clouds” due to their resonant nature, are used in soundtracks and soundscapes.

Check out an example of an audio “cloud” below

Speeding up and Slowing Clips

The ability to speed up and slow down clips independently of each other is one of the, if not the keystone property of granular synthesis. This breakthrough has opened new doors for all musicians and makes studio production much more efficient. Moreover, since signals can now be warped for pitch independent of time, vocal textures added to mixes are more diverse than ever before.

Keys / Pad Sounds

Granular synthesis is excellent at creating unique key and pad sounds. Since these instruments are usually associated with long, stagnant chord drones, they often have simple transients.

A transient refers to the shape of the audio signal waveform. Since the transients are relatively straightforward, it is easy to replicate or loop the grains of a signal in order to replicate these sounds. Granular synthesis is a great way to spice up your key sections, giving you the appearance of a keyboard/pad patch as unique as a snowflake.

Adding Textures

Many artists use granular synthesis to add a unique flair to their vocals, drums, or just fill in frequencies that are hard to come by under normal circumstances. For example, Flume, a popular EDM artist, uses granular synthesis on many of his drum fills to produce many eerie yet intriguing sounds.

Hear an example of his music using granular synthesis

Using Asynchronous synthesis here will especially produce some dynamic textures. Don’t forget to play around with modulation specific parameters, such as grain size/grain texture.

See Asynchronous synthesis in play here

Software Where Granular Synthesis can be Found

A growing number of VSTs, plugins, and DAWs are incorporating granular synthesis in their designs. In fact, many DAWs now come with built-in granulators for further experimentation. Let’s take a look at which electronic workstations include some version of a granulator, and then dive into external effects/instruments that use granular synthesis as a way of processing.

Granulators Within DAWs

Granulator 2 by Ableton

Granulator 2– Ableton granulator 2 is included with any purchase and license of Ableton. It is available for download within the company website.

Elastic Audio– Pro Tools’ version of audio editing with granular synthesis. It comes with the purchase of software.

Example of Elastic Audio being used in Pro Tools

Fruity Granulizer– FL studios’ native plugin for granular synthesis. Included with the purchase of software.

Fruity Granulizer

In case your DAW isn’t listed, or you desire a standalone plugin, here are two options:

Common digital effects using Granular synthesis

Ableton Warping– Ableton’s warp used to change the speed and/or pitch of a signal without one affecting the other.

Autotune by Antares Audio Technologies– This buzzworthy, sometimes controversial plugin uses granular synthesis to pitch correct vocals.

Melodyne by Celemony– Melodyne uses granular synthesis to remove unwanted sounds and employ pitch correction. Melodyne is an excellent tool for cleaning up any piece of audio- Outside of music, it is used commercially in podcast/newscasts to remove transients of wind, rustling leaves, and other undesired outdoor noises.

Omnisphere by Spectrasonics– Omnisphere, a powerful synthesizer, is known for its deep, lush pad sounds created with granular synthesis. It righteously boasts having more than 7000 built-in sounds to choose from!

Hardware Granular Synthesis

Granular synthesis is not limited to just software. Many synthesizers are built specifically for this method of experimentation. Moreover, the sensation of a physical instrument often helps with the retention of the process itself. If you can, experiment on hardware to get a firm understanding of granular synthesis.

Particle Granular Delay by Red Panda Lab– This guitar/effect pedal comes built-in with all the needed parameters with the advantage of being extremely compact.

Clouds by Mutable Instruments– This physical synth is built specifically for granular processing. It comes with a built-in all-pass filter, which allows the synth to smooth out/divide the harshest of transients, making it a very powerful tool.

Nebulae by Qu-bit Electronix– An extremely compact yet powerful granular synthesizer, the Nebulae allows for easy creating on-the-go!

Final Thoughts

Granular synthesis is a revolutionary breakthrough within the audio world. Its property of separating the variables of pitch and speed are priceless, and it will continue to inspire positive advancements among producers and engineers alike.

Get a grasp on the modern granular synthesis, and be a part of the innovation process.

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