Synthesis Types and Techniques

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Sound and audio synthesis (learn more) includes lots of methods and techniques for making and changing sounds.

Each one of these methods has its own rules and gives us different types of sounds.

Learning about these different types of synthesis techniques helps us understand not just the technical side, but also the artistic side of the electronic sounds we hear in today’s music.

These types of synthesis can be achieved with both hardware and software synthesis (learn more).

Frequency Modulation (FM) Synthesis

FM Synthesis, or Frequency Modulation Synthesis, is a unique way of creating sounds.

It does this by changing one sound signal with another.

It’s especially good at finding harmonic tones that other methods can’t reach. FM synthesis is used a lot in sound design. It’s great for making metallic sounds or bell-like noises with a lot of depth. But its sound-shaping abilities let creators make sounds that are both natural and man-made. This makes it very flexible.

FM8 VST Screenshot
The FM8 Virtual FM Synthesizer by Native Instruments

Here’s a high level overview of how FM synthesis works:

  • The frequency of a “carrier” waveform is changed by modulating its frequency with a “modulator.”
  • The main components of FM synthesis are the carrier frequency, the modulating frequency, and the modulation index.
  • Carrier Frequency: The carrier is the basic frequency that will be altered. In musical terms, it’s the basic note that you hear.
  • Modulating Frequency: The modulator is a frequency that changes the carrier. This frequency is often too high or low for us to hear, but it changes how the final sound feels to our ears.
  • Modulation Index: The modulation index lets us control how much the main frequency is changed by the secondary frequency. It’s like adjusting the sound’s brightness or harshness.
  • Algorithm: The way in which the carrier and modulating frequencies are connected in an FM system is called the algorithm. Different algorithms can produce different timbres.
  • Complex Sounds: By using multiple carriers and modulators, you can create more complex and rich sounds.
  • Advantages: FM synthesis can create a wide range of timbres, from simple sine waves to complex evolving sounds. It’s very efficient and requires less computational power compared to other synthesis methods.
  • Learning Curve: FM synthesis can be complex to understand and manipulate compared to other synthesis methods like subtractive synthesis.

Learn how FM synthesis works, in-depth, in this full guide.

Granular Synthesis

Granular synthesis breaks down audio into tiny parts, called grains. Each grain can be changed to make complex sound textures that can’t be made with other synthesis methods.

You can change the size, pitch, and envelope of each grain to make everything from twinkling pads to detailed rhythmic patterns. Changing the grains in real-time or in pre-set sequences opens up even more creative options.

Granular synthesis has many uses like evolving and alien-like sounds, ambient textures, complex lead sounds and new percussion elements

Cherry Audio Granular Synth VST
Cherry Audio Granular Synth VST

Here’s a high level overview of how granular synthesis works:

  • Sampling: The first step in granular synthesis is to take an audio sample. The length of this sample can vary from a fraction of a second to several minutes.
  • Splitting into Grains: The sampled sound is then divided into small pieces called ‘grains’. These grains are typically between 1 and 50 milliseconds long. This process is known as granulation.
  • Windowing: Each grain is then enveloped with an amplitude shape to prevent clicks or pops.
  • Reorganization and Layering: These grains are then re-sequenced, layered, or otherwise manipulated.
  • Parameter Manipulation: Various parameters of the grains such as pitch, time, volume, panning, etc., can be manipulated to create a wide variety of sounds.
  • Resynthesis: Finally, the grains are recombined or ‘synthesized’ back together to create a new sound. This can be done in a structured manner or randomly.
  • Real-time Playback: In many cases, granular synthesis is done in real-time, allowing for live performances and interactive sound design.
  • Advantages: Allows for intricate sound design, time-stretching, pitch-shifting, and creating complex textures from simple sound sources.
  • Learning Curve: Can be steep initially due to its complex nature

Learn how to do granular synthesis in-depth in this guide.

Additive Synthesis

Additive synthesis uses many sine waves at different pitches to make sounds.

This method is based on the idea that any sound, no matter how complex, can be split into its basic parts—harmonics. By using harmonics through additive synthesis, sound designers can make detailed and complex sounds.

Making sounds using additive synthesis starts with the simplest waveform: the sine wave. By carefully changing and layering these sine waves, a wide range of sounds can be made.

NI Razor Interface Screenshot
Native Instruments Razor Additive Synth

Here’s a high-level overview of how additive synthesis works:

  • Additive synthesis is a sound synthesis technique that creates timbre by adding sine waves together.
  • The idea here is based on the Fourier theory that says that we can make any waveform by adding up simple sine waves of different frequency and size.
  • Each individual sine wave, also referred to as a partial, harmonic, or overtone, contributes a unique pitch to the overall sound.
  • Fundamental Frequency: the lowest frequency, determines the perceived pitch of the sound. Higher frequencies, called overtones, shape the timbre or color of the sound.
  • Individual Control: the amplitude and frequency of each sine wave can be individually controlled, allowing for the creation of complex and dynamic sounds.
  • Uses: often used to mimic acoustic instruments, as it can accurately reproduce the harmonic structures of these instruments.
  • Challenges: While the concept is simple, the challenge of additive synthesis lies in the detailed control required to achieve the desired sound. Can be very CPU-intensive due to the number of sine wave oscillators that need to be processed simultaneously.
  • Advantages: can create complex and unique sounds by combining basic waveforms, providing complete control over the harmonic content of the sound.
  • Learning Curve: can be steep as it involves understanding complex concepts of sound wave manipulation and layering multiple waveforms to create rich and diverse sounds.

Learn how to do additive synthesis in-depth in this guide.

Subtractive Synthesis

Subtractive synthesis starts with a sound that has lots of harmonics. These various frequencies are then filtered out to get the sound that is wanted.

The first step in subtractive synthesis is to make a waveform. This could be a sawtooth, square, or triangle wave. These waveforms are used because they can produce lots of different harmonics. This means we have a broad range of sounds to start with.

Next, these waveforms are passed through filters that remove specific frequencies. This is the main part of subtractive synthesis, complimented by shaping the amplitude envelope – and thus the loudness and tone – of the sound.

By changing the cutoff frequency and resonance of the filters, we can boost or reduce certain frequencies.

Moog Hardware Synthesizer
A Hardware Subtractive Synth by Moog

Here’s a high level overview of how subtractive synthesis:

  • Starting Point: The process begins by generating a waveform with a lot of harmonics, such as a square wave or sawtooth wave.
  • Filtering: filters are applied to subtract (i.e. remove) frequencies, hence the term “subtractive”. This can be a low-pass, high-pass, band-pass, or notch filter.
  • Modulation: The filters can be modulated using an envelope or a low-frequency oscillator (LFO), which can change the sound over time. The amplitude of the sound is controlled by an amplitude envelope, which can also change over time.
  • Layering: The process can be repeated with multiple oscillators and filters to create complex sounds.
  • Advantages: widely used and understood, very versatile, works well for creating realistic sounds, good balance between ease of use and depth of control.
  • Learning Curve: generally one of the easier forms of synthesis to learn, especially for beginners. Logical and intuitive process

Learn how to do subtractive synthesis in-depth in this guide.

Wavetable Synthesis

Wavetable synthesis uses recordings of waves and puts them together to make complex sounds that change over time.

This technique has improved a lot since it first started. Old wavetable synthesizers could only use a few types of waves and could not change them very much. But now, there are many more types of waves to choose from, and you can change them in more ways.

You can also control them in real-time.

Modern wavetable techniques use digital signal processing to let people change smoothly between different waves within a wavetable, making it easier to create a variety of sounds. You can even import your own waveforms and change them however you like.

Wavetable synthesis can create soft, changing pads or harsh, sharp leads. Compared to something like FM synthesis, which makes complex sounds full of harmonics, wavetable synthesis is a more straightforward and visual way to create and change sounds.

Wavetable synthesis is great for sounds that change over time, and FM synthesis is known for sharp, metallic sounds. But they can also be used together to take advantage of their special features.

Serum Interface Screenshot
SERUM Wavetable Synthesizer by Xfer Records

Here’s a high level overview of how wavetable synthesis is done:

  • Initial steps: you start by selecting a series of waveforms, which can be either predefined or user-generated. These waveforms are then stored in a table or a ‘wavetable’.
  • Playback: the synthesizer cycles through this wavetable, smoothly transitioning from one waveform to the next to create a unique and complex sound.
  • Sound Generation: The rate at which the synthesizer cycles through the wavetable is determined by the frequency of the note being played.
  • Modulation: You can also modulate various parameters such as the amplitude, pitch, and filter cutoff frequency to further customize the sound.
  • Effects Processing: The sound can also be shaped by applying effects like reverb, delay, or distortion.
  • Advantages: very versatile, variety of sounds can be created from a single wavetable, capable of producing very complex and evolving sounds difficult to achieve with other forms of synthesis, can emulate other types of synthesis to some degree
  • Learning Curve: can be steep for beginners to grasp a variety of concepts all at once, but synths have user-friendly interfaces and preset libraries

Learn how to do wavetable synthesis in-depth in this guide.

Spectral Sound Synthesis

Sound synthesis through spectral technique is a high-tech method.

It breaks down sound into its basic frequencies. This lets us tweak and shape the sound in detail by working with sound spectral analysis. This is a study of the frequency content of sound waves to understand how they are built.

By working with specific frequencies, we can change sound in tiny ways. This gives sound creators and musicians a lot of control. One can change frequency response, add or remove harmonic content, and even change between different spectral states. This is crucial for creating dynamic soundscapes that can change over time.

The process can create a one-of-a-kind sound quality, which is hard to get with traditional methods. This is especially useful in electronic music where new sounds are highly valued.

Spectral synthesis is also important in improving sound quality. By working with the spectral parts of a sound signal, engineers can get rid of unwanted noise or boost certain parts of a recording. This makes the overall sound quality better for a clearer, more defined listening experience.

Akoustic Spectral Synthesizer by Sampleson

Here’s a high level overview of how spectral sound synthesis is done:

  • Sound Sampling: The process starts with the sampling of any existing sound like a musical note, a voice, or even an ambient noise.
  • Fourier Transformation: The sampled sound is then processed through a Fourier transformation. This mathematical process breaks down the complex waveform of the sound into simpler sine waves, each with its own frequency, phase, and amplitude. This is called the sound’s “spectrum“.
  • Sound Synthesis: Using the spectral information, new sounds are synthesized. Each sine wave can be manipulated individually, allowing for a high level of control over the output sound. This is done using a process called inverse Fourier transformation.
  • Sound Editing: The synthesized sound can then be edited and modulated further, adding effects or combining it with other sounds to create the desired final product.
  • Advantages: High Quality Sound, Control and Flexibility, Unique Sounds Can be Created
  • Learning Curve: challenging to understand and learn due to complex mathematics involved, time-consuming.

Learn how to do spectral sound synthesis in-depth in this guide.

West Coast Synthesis

West Coast Synthesis is a unique music-making style based on changing the sound’s tone.

Don Buchla, a resident of the lively city of San Francisco, created it. His method was different from East Coast Synthesis, also known as Moog-style synthesis, that mainly used subtractive synthesis techniques.

West Coast Synthesis is known for using Buchla’s musical tools, which allow a wide variety of sound experiments.

These tools often start with basic sound waves like sine or triangle waves. They then use wave-shaping methods to add more layers and depth to the sound. This playful approach often results in the creation of intricate, changing sounds and textures.

Unlike typical sound reduction filters, West Coast systems use low-pass gates. These are a mix of a filter and an amplifier that shape the loudness and tone of a sound in a more natural, drum-like way.

A Modular Synth Setup
Modular Synth Setup

Here’s a high level overview of how west coast synthesis is done:

  • Sound Generation: Starts with complex oscillators that have rich harmonic content and multiple outputs that can be dynamically altered in terms of timbre.
  • Modulation: Uses techniques such as frequency modulation (FM), amplitude modulation (AM), and wave shaping for more dynamic and unpredictable results.
  • Sequencing: West Coast synthesis often uses non-traditional sequencing techniques like stochastic and algorithmic patterns, which can create more random and evolving sequences.
  • Sound Shaping: Instead of traditional subtractive filters, West Coast synthesis often uses low pass gates (a combination of a low pass filter and a Voltage Controlled Amplifier that varies output amplitude) for shaping the sound. This approach tends to create more percussive and organic sounds.
  • Advantages: Unique and experimental sounds, allows for creativity and exploration, great for complex and evolving sequences.
  • Learning Curve: can be quite complex and challenging to learn due to its unconventional approach, requires lots of experimentation and time

Learn how to do west coast synthesis in-depth in this guide.

Sample Based Synthesis

Sample-based synthesis is a method that uses real-life sounds or instruments. These sounds are captured by a recording device and are stored in a digital format, which forms the basis for making new sounds.

The great thing about sample-based synthesis is that it’s flexible. With smart sampling techniques, you can turn a simple sound clip into something completely different.

You can change the pitch, length, tone of the sample, and even reverse or twist the sound. You can also layer it with other samples or completely new generated sounds. This way, you can keep the real sound’s details and also try out new sound designs.

Technology has really helped sample-based synthesis. Modern sampling tools and software synthesis instruments (learn more) give users many ways to shape and change samples.

Mother Source Interface Screenshot
Mother Source Sample-Based Synth by Miclop

Here’s a high level overview of how sample based synthesis is done:

  • Source Material: Pre-recorded audio samples (whether you download them or record them yourself) are used as the source material.
  • Processing: These samples are then processed and manipulated by the synthesizer. The processing could involve altering pitch, applying filters, reversing, looping, changing phase, or adding effects.
  • MIDI Control: The processed samples are then typically controlled using MIDI (Musical Instrument Digital Interface) signals. You can play the samples back live like an instrument or program/sequence them. This allows for control of pitch, volume, and other sound qualities.
  • Layering: Often, multiple samples and sound sources are layered together to create more complex sounds.
  • Advantages: offers realism in sound design – nuanced and complex tones, very versatile way of working, allows for a new level of creativity in sound design.
  • Learning Curve: Very beginner friendly

Learn how to do sample-based synthesis in-depth in this guide.

Vector Synthesis

Vector synthesis is a form of sound generation that allows sound designers to mix and change multiple waveforms in real time. This neat sound-making method was first used by Sequential Circuits in the Prophet VS synthesizer.

When you use vector synthesis, you’re like an explorer. You can move through different sounds by blending and swapping between waveforms positioned at the corners of a vector space.

Think of it like a grid with an X/Y axis.

Users can pick different waveforms, like analog-style waves, digital FM tones, or samples, and place them on each corner of the vector grid. Then, they can move between them using a joystick or automation.

You can do some pretty unique things with vector synthesis. You can create evolving soundscapes, expressive leads, and complex pads that change in sound quality over time.

Vector Hardware Interface
Vector Hardware Synth by Beetlecrab

Here’s a high level overview of how vector synthesis is done:

  • Waveform Selection: Select several different waveforms you want to use. These can range from simple sine or square waves to more complex or custom waveforms.
  • Vector Plane Creation: Create a vector plane, which is a 2D space where each corner represents one of your waveforms.
  • Defining a Path: Define a path within the vector plane. The path determines how the waveforms are blended together over time.
  • Manipulation of Path: You can manipulate the path manually, or use an envelope follower or LFO (Low-Frequency Oscillator) to control it automatically.
  • Sound Output: The output is a smoothly changing, morphing sound that transitions between the different waveforms according to the path you’ve defined.
  • Advantages: Allows for the creation of complex, evolving sounds that change character. Versatile, especially for live performance.
  • Learning Curve: Can be quite complex and time consuming to learn initially

Learn how to do vector synthesis in-depth in this guide.

Physical Modelling Synthesis

Physical Modelling Synthesis is a complex way to create sound. It uses math to copy the sound properties of real instruments.

This method makes audio by copying how a sound works in nature. It looks at how sound bounces off things like strings and air. By changing these models, people can mimic the subtle actions of real instruments.

A key part of this technique is controlling the harmonics. By adjusting the physical aspects, users can control the harmonic series and overtones of the sound being generated.

This brings a level of detail to the sound that other methods can’t match. This control is very important when trying to mimic real instruments. It allows the recreation of complex sounds and the expressiveness of orchestral instruments, guitars, and woodwinds.

Anyma Phi Hardware Interface
Anyma Phi Physical Modelling Synthesizer by Aodyo

Here’s a high level overview of how physical modelling synthesis is done:

  • Understanding the Instrument: The first step in physical modelling synthesis is understanding the physical properties of the instrument you want to model. This includes its shape, the materials it’s made of, and how it produces sound.
  • Creating a Mathematical Model: The next step is to create a mathematical model that describes its physical properties. This model is a set of equations that describe how the instrument interacts with sound waves.
  • Implementing the Model: After that it needs to be implemented in a computer program. This program will use the model to calculate the sound output of the instrument.
  • Testing and Refining the Model: Once the model is implemented, it needs to be tested and refined.
  • Using the Model: The model can then be played live using a MIDI controller or programmed/sequenced to play specific notes or rhythms.
  • Advantages: Best way to make realistic sounds, flexible in it’s application and very efficient.
  • Learning Curve: Extremely complex – requires a good understanding of both physics and mathematics. It also requires skills in computer programming.

Learn how to do physical modelling synthesis in-depth in this guide.

What to Do Next

Thanks for reading this complete guide on synthesis techniques for beginners. Next up, deep-dive into one area you’d like to get started with: