Beginners Guide To Synthesis

What is synthesis?

Synthesis is simply creating your own sound from scratch through the use of electrical signals. However, you can further shape the sound through the use of various features & aspects (oscillators, envelops, LFO's, etc) that we'll further look into together.

Frequency & Pitch

Frequency is very important when it comes to music technology, especially designing sounds, which also is heavily linked with pitch. Frequency is the rate of a sound wave moving in and out and this is measured in Hz (Hertz meaning cycles-per-second), so in this case, a sound wave with 10Hz vibrates 10 times per 1 second.

As stated earlier, frequency is interlinked with pitch. To understand the connection in a more simple way: the lower the frequency, the lower the pitch & vice-versa. When an oscillator's (an oscillator is basically what makes the sound) frequency is doubled, the sound's pitch moves up by one octave.

Wave forms

When it comes to wave forms, you firstly have the four basic and most common ones: Sine, Sawtooth, Square & Triangle.

Sine:
By looking at the wave form, you can describe it as a river with continuous flow because it has a simple movement of going up & down rather than moving in an obscure pattern. By listening to it, you could easily separate it from the other three because it has less characteristics & it's less complex. For example, you would mainly describe it as "pure", "hollow", maybe even compare to air.

Sawtooth:
Unlike the Sine wave form, the Sawtooth has a jagged pattern when you inspect the wave form, hence the name, however it sounds similar to the Square wave form. It's perhaps the most aggressive sounding wave form that has a buzz to it, which may also sound very harsh.

Square:
The Square wave has a series of rectangles above & below the middle line, consisting of the same shape. It has more body and a distinctive sound compared to Sine, however it sounds much more natural and less harsh compared to Sawtooth. You may recognize this wave form from various Nintendo games.

Triangle:
The triangle wave appears to look like a mixture of a sine & square wave when looking at the wave form, as it looks like a graph chart showing a rise, peak and decline then back to rise. A triangle wave form sounds high and thin in tone.

Common Editing Features

Oscillators:
Oscillators create sound by generating a repeating signal, you'll also find that oscillators are very common in modern synthesis. An output of an oscillator normally consists of: frequency, amplitude & tone.

LFO:
Stands for "Low Frequency Oscillator", it is an electrical signal that plays the same role as an oscillator but at a much lower frequencies (namely 0-20 Hz) which also gives you the advantage of choosing specific frequencies. By modulating the pitch, you'll simulate a vibrato effect, however if you modulate the amplitude, you'll get a tremolo effect.

Envelopes:
Envelopes mainly contain four parameters: Attack, Decay, Sustain, Release. These are very important in regards to designing sound.

The attack controls how fast the sound reaches full amplitude so the faster the attack, the more specific the impact would be in terms of when you activated the sound (hit the button, key, etc). The slower you set the attack, the more the sound will fade in.
The decay correlates with the sustain, so the decay determines how quickly/slowly the sound reaches maximum amplitude and fade down to the set sustain level. The sustain parameter dictates how long the sound will go on for. The release will effect how long the sound will fade to silence after you release the note.

Filters:
Filters help you achieve a certain sound you're looking for and there are various filters available in DAW's today, but we'll just look at the most common ones:

Low-Pass Filter:
Imagine a line (in this case it's the "limit"). Everything above that line becomes irrelevant and you only hear what is below it, this is how a low-pass filter works and is commonly used to enhance sounds that play role of bass.

High-Pass Filter:
A high-pass filter works exactly the same as a low-pass filter, just in the opposite manner. Instead of ignoring what's above the line, everything above the line becomes relevant and the main focus. You can use a high-pass filter to bring out the brightness of some sounds.

Band-Pass Filter:
A combination of both the low-pass and high-pass filter, you can describe a band-pass filter as a more flexible and specific filter as it allows you to choose exactly what parts do you want to cut off and what parts you want to focus on.

Types Of Synthesis:

Additive Synthesis - Combines the tones, usually harmonics of varying amplitude.
Subtractive Synthesis - Filters sounds to shape harmonics.
Frequency Modulation Synthesis - To modulate a carrier wave through the use of a modulator. (In other words, using an oscillator to control the output of another oscillator).
Sampling - Using recorded sounds as a foundation so that you will then modify the sound of the recordings.