Fundamentals of Audio Synthesis – Sound Design For Beginners

A little over 3 years ago I was a complete beginner. I was struggling to create sounds that I liked and had heard in my favourite songs. Since then I have become comfortable with sound design and have a strong understanding of it – to a point where designing sounds has become a big part of income and allows me to feed my family while doing what I love. Getting there hasn’t been easy but it has been fun and is well worth the time investment.

Good sound design is at the heart of any successful record. It is therefore paramount that you as a producer should understand the fundamentals of audio synthesis and sound design. This will not only help you with designing sounds, it will also improve your mixing and understanding of signal flow and processing. All that aside – sound design is also just incredibly fun to experiment with, so learning sound design is well worth your time!

In this tutorial I will cover 10 fundamental topics that will help you develop a basic understanding of sound design. I will also provide some helpful resources that were a huge help for me when I was just getting started in the world of sound design.

  1. Oscillators and The Five Basic Waveforms
  2. The ADSR Envelope Explained
  3. Filters
  4. Modulation
  5. LFO
  6. Monophonic & Polyphonic
  7. Unison and Detune
  8. How to Make A Pluck
  9. How to Make A Pad
  10. How to Make A Lead
  11. How to Make A Reese Bass
  12. The best way to practice sound design

The Five Basic Waveforms

In almost any synthesizer you will have access to the following five basic waveforms:

  1. Sine
  2. Triangle
  3. Square/Pulse
  4. Saw
  5. Noise

I recommend listening to each of these sound waves and taking a mental note of characteristics.
A sine wave is a very clean sound, it has no harmonics, just a single fundamental – think of a heart rate monitor going “beep, beep, beep”.


A triangle wave has a similar sound to a sine wave but it does have some added harmonics – think of a flute.


A square wave is packed with harmonics and has a sound reminiscent of 8-bit video games.


A saw wave is rich in harmonics and has quite a rough and harsh sound to it – some words that come to mind are – gritty and buzzing.


Noise is completely random frequencies spread across the entire spectrum and sounds like a TV or Radio that hasn’t been tuned – “TSHHHHHHHHHHHH”. Noise is extremely useful for sound designers and can be used to make anything from Claps, to Sweeps, to Hi-Hats, to adding top-end to synths and loads more.

The ADSR Envelope Explained

Short attack ADSR

ADSR stands for Attack, Decay, Sustain, and Release. We use the ADSR envelope to control the amplitude of our waveform over time.
When we push a key on our synthesizer the very first stage that gets triggered is the Attack.


The Attack stage will control the amount of time the sound takes to reach its peak volume level when a key is pressed.


Think of a piano, when you press the key you instantly hear the sound, that means the attack is at 0.

What about a pad?

When you press a key on a pad sound it might take 2 seconds for the sound to reach its maximum loudness. In this case, the Attack would be set to 2 seconds.


Here is an example of a sound with a short attack


Here is an example of a sound with a long attack


The next stage that gets triggered when we press a key is the Decay.

Decay will begin immediately once the attack stage is complete. Decay is the amount of time it takes the sound to decrease in volume to the level of the Sustain.

If sustain is set to the maximum then the decay parameter will have no effect on the sound and becomes obsolete.


Here is an example of a sound with a short decay


Here is an example of a sound with a long decay


Sustain is the level that the sound will remain at while we are holding the key down and the decay stage is finished.


Here is an example of a sound with a maximum sustain


Here is an example of a sound with a low sustain


Release is the amount of time it takes for the sound to decrease in volume until it is silent. This stage only triggers once we release the key.


Here is an example of a sound with a short release

Short attack ADSR


Here is an example of a sound with a long release

Filters

Low Pass
High Pass
Band Pass
Notch

Think of filters like the tongue and lips of your synth. We can move them up, down and around to shape our sounds, to make them appear up front and loud or to push them back in the mix.


There are a ton of different filters available in the popular synths of today such as Serum and Massive. But I will go over a few basic filters that will be sufficient to make almost any sound you can think of.


Low Pass Filter – Removes all frequencies that are above the cutoff point. Most commonly used for plucks, pads, leads and basses.

High Pass Filter – Removes all frequencies below the cutoff point. Most commonly used for growls, and other sounds that need a vowley character.

Band Pass – Removes frequencies that are above and below the cutoff. Great for sweep effects and in some cases leads.

Notch – Scoops out frequencies at the cutoff point. Good for creating distorted bass sounds.

Modulation

Think of modulation as using one thing to control the movement of another. With modulation, we typically use the ADSR envelope or an LFO (explained below) and map it to another parameter like volume, pitch or filter cutoff.


Here is an example of a Saw Wave with a Low Pass filter on it, the Low Pass Filter’s “Cutoff” is being modulated by an ADSR Envelope to create a nice little wub sound.

LFO

LFO Stands for Low-Frequency Oscillator. It’s really just an Oscillator that is played back a lot slower than usual and then gets used to modulate other parameters like pitch, volume, filter cutoff etc.


The easiest way to think of an LFO is to think of an ADSR envelope that is not restricted by stages, as soon as a key gets pressed the entire shape of the LFO cycles through on repeat until you release the key.


LFOs are typically good for creating rhythms, or things that require repetitive motion like vibrato, or making a dubstep growl that is constantly changing.
Here is an example of a Sine Wave LFO being used to modulate the pitch of a Saw Wave.

Monophony & Polyphony

Most synths will give you an option to choose between mono and poly.
This simply dictates how many notes can be played at the same time.
Mono, meaning one, and poly, meaning multiple. So if you are creating a lead and don’t want notes to overlap, mono will work. However, if you are creating a patch that will be playing chords you will need a polyphonic synth.

Unison & Detune

Unison is the number of voices an oscillator will put out.


If you have a saw wave and set the unison to 2 – when you press a key down the synth will put out 2 saw waves both at the exact same pitch. These are called voices. If you played a chord with 3 notes and 2 voices of unison the synth would output a total of 6 waves, 2 for each key that is pressed.


Most synths will typically offer unison in values of 1, 2, 4, 6 and 8. However, newer synths and a lot of the ones you will be using will offer up to 32 voices per oscillator.
Remember how I said that increasing unison will cause the synth to output multiple waves at the same pitch?


Well, there is another parameter called “detune” that will shift the pitch of each voice slightly so that they are all out of tune with each other.


The further you push the detune, the more the timbre of the synth becomes dissonant. A high amount of Unison combined with Detune is the basis for sounds like the very common Supersaw.


Unison and Detune can also be used to make sounds “wide”. If the synth you are using has a wideness parameter, it may do nothing until you feed it some unison and detune.

Serum, for example, is set up to be wide by default but will play everything back in mono until you increase unison and detune, or add effects to it.


Here is an example of a saw with 16 voices of unison and generous detune. Notice how the sound spreads really wide as we increase the unison and detune.


We can also use detune to create a pulsating effect, here is a saw wave with 2 voices of unison that are detuned until we can hear a pulsing effect.


Let’s get on to making some common sounds…

The Pluck

Commonly referred to as the “Deadmau5 pluck”.
Follow this process to create the Deadmau5 pluck

  1. Set both oscillators to saw waves, both with 4-16 voices of unison and a bit of detune
  2. Enable a low pass filter
  3. Map an ADSR envelope to the filter cutoff
  4. Set the attack to 0
  5. Set the sustain to 0
  6. Set the decay to around 200-700ms depending on how long you want the pluck
  7. The release can be set to 0 as this will have no effect on the sound because of the sustain being at 0


Note how I set the decay up AFTER the sustain, this is because the sustain is set to max by default, so adjusting the decay before the sustain will produce no change in sound. I always want to be listening to the changes I make. If your synth’s sustain parameter is set to 0 by default then, by all means, you can set up your decay first.

The Pad

The steps to create a basic pad are as follows:

  1. Set your Oscillators to Saw Waves with high unison and detune
  2. Enable a low pass filter
  3. Set the cutoff to around 600-800Hz or just until you hear all the harshness disappear
  4. Set your Attack to around 1.5s or longer if desired
  5. set your Sustain to around half way
  6. Set your Decay to around 1s
  7. Set your Release to around 1s
  8. Assign the envelope we just created to the cutoff of your filter, and ensure that the modulation amount is very low so that the cutoff only moves very slightly
  9. Add generous amounts of reverb with a long decay and large room size and try out other effects like delay, phasers, flangers, chorus, etc.


Note how the ADSR envelope has been set up to make the sound gently rise and fall.

The Lead

Lead is a very broad term but typically a lead is a centered and upfront sound that needs to draw attention. Here are some basic steps to follow to create a lead:

  1. Use either a Square or Saw wave
  2. Enable a bandpass filter and set the cutoff to around 1kHz
  3. Assign an LFO to the fine tune and the amount very low to create a vibrato effect
  4. Set the LFO to around 2hz or slower
  5. Add generous amounts of reverb and delay
  6. Experiment with distortion and saturation to give the lead some grit
  7. Try adding other waveforms


There are a million ways to make a lead sound, so experiment with all the waveforms and filter types + effects and try to make something unique.

The Reese Bass

  1. Use either a Saw or Square Wave
  2. Set Unison to 2 or more and Detune them until you get a nice pulsating effect
  3. Enable the low pass filter and bring down the cutoff until the harshness is removed (around 200-800hz)
  4. Experiment with distortion and saturation to add some character to the sound
  5. You can also modulate the filter cutoff slightly with an LFO to give it some movement

How to Practice Sound Design

One of the tried and tested methods for improving your sound design skills is to practice reverse engineering presets.


To do this you simply find a preset you like and start disabling effects one by one until you strip the preset back down to just the oscillator – then you can try to re-build the preset based on what you learned from reverse engineering it.


While this method is great, there is another method I used that without a doubt shaved years off the learning curve for me and that is Syntorial.
Syntorial is an interactive, video game-like course that teaches you how to program synth patches by ear.

It combines video demonstrations with interactive challenges in which you program a built-in soft synth. And they’ve got a free demo that includes the first 22 lessons for free.


The entire course took me around 2 months to complete as I was going through the lessons relatively slowly on my daily commute to work. But I cannot recommend it enough as it took me from knowing absolutely nothing about sound design to being able to pick out sounds that I like from my favourite songs and being able to recreate them without too much difficulty.

Here’s an example of a remake of Above and Beyond’s My Own Hymn that I made a while ago:
.

Check it out at www.syntorial.com. (Note, this is an affiliate link and by clicking on it and purchasing the product, I earn a small commission and get motivated to continue writing this content!)

Now that you’ve got the basics down, how about learning a bit more about drum synthesis?


Frequently Asked Questions

Where can I learn sound design?

Syntorial is probably the best learning resource for subtractive synthesis, it takes you from complete beginner to advanced with an interactive course.

There are also a few good YouTube channels for learning sound design:

  • Mr Bill – Glitchy, granular sound design and out of this world ableton workflow.
  • ARTFX – Crazy awesome Neuro DNB sound design sessions.
  • SeamlessR – Known for his how to bass series.
  • Basic Wavez – Drum synthesis tutorials and more.
  • Au5 – check out his awesome drum synthesis tutorials.
  • Some artists stream their production sessions like Virtual Riot, and Kill The Noise.

 What is synthesis in terms of sound design? 

Synthesis is the process of using a hardware or software synthesizer to generate soundwaves, and then either adding or subtracting frequencies from the soundwaves to create new and interesting sounds. 

How does subtractive synthesis work? 

Subtractive synthesis is the process of altering the tibre of an audio signal often by removing frequencies by use of filters and other methods. Similar to how the human voice works. We generate a sound with our vocal chords and then remove frequencies using the shape of our mouths to create different vowel sounds.  

How does additive synthesis work? 

Additive synthesis is a technique whereby we use a synthesizer to add two or more sine wavez together which leads to the addition of harmonic overtones.  

Is Serum a subtractive synth? 

Serum is marketed as a wavetable synth. However, it makes use of subtractive methods like filtering, and becuase it has multiple oscillators it also has additive capabilities. There are also FM capabilities built in to it. So to answer the question – Serum is capable of multiple forms of synthesis. 

What does FM stand for in music? 

FM stands for Frequency Modulation, which is the process of using one sound wave to modulate the pitch or frequency of another sound wave.

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