Introduction to Music Production 10 – Basic Sound Synthesis
Sound synthesis is a method that lets a producer create sounds virtually from scratch. Synthesizers oscillate waves (sometimes sample-based) to generate a tone. This post isn’t a tutorial on how to perform various types of synthesis because there are many types and facets to it. This should give an overview to understand some of the concepts associated with all types of synthesis.
Here are some common key terms and functions associated with synthesis.
Oscillator – a device that oscillates (repeatedly plays) a wave shape to generate a tone. The speed of the oscillator determines the pitch/frequency of the tone
Waveform – the shape and form of a signal such as a wave moving in a physical medium or an abstract representation. Common waveforms in synthesis are Sine, Square (PWM/Pulse Width Modulation), Triangle, and Saw.
Wavetable – a table of stored sound waves that are digitized samples of actual recorded sound. This isn’t always a single waveform shape (i.e. a saw wave), but a collection of multiple a synthesizer can scan through.
Voice – Think of adding more of the same instrument. Adding voices can add a chorus effect, and create a more dense sound.
Filter (See EQ) – A filter can attenuate and boost frequencies.
Velocity – this is the intensity in which a note is pressed.
Modulator – controls to change (modulate) parameters
Envelope – a type of modulation that changes levels occurs over time. It is usually associated with amplitude, but envelopes can control many different parameters.
ADSR – these are the parameters of an envelope. Attack is the initial onset of a sound that begins when a note-on MIDI message is received, decay is the amount of time the note takes to reach a ‘settled’ volume, the sustain is the ‘settled’ volume, and the release occurs when the note-off MIDI message is received.
Arpeggiator – A type of modulator that ‘performs’ arpeggiation. This could be notes, rhythms, or both.
LFO – low frequency oscillator. This is a type of modulator that changes parameters based off of a waveform set to a certain speed.
CV (Control Voltage) – an analog method of controlling synthesizers, drum machines, and other hardware.
Keytracking – a concept that allows a user to have parameters change based off of what notes are input.
There are many different types of sound synthesis, both analog and digital. Every type of synthesis has a unique general method of achieving sounds, but most modern synthesizers make use of multiple types integrated.
Additive – multiple sine waves are played at different frequencies to achieve sounds.
FM (Frequency Modulation) – the timbre of a simple waveform (such as a square, triangle, or sawtooth) is changed by modulating its frequency with a modulator frequency that is also in the audio range.
Subtractive – multiple waveforms are played together and filters are used to shape the frequency spectrum.
Granular – a method by which sounds are broken into tiny grains which are then redistributed and reorganized to form other sounds.
Learning how to use synthesizers, both digital and analog, software and hardware, simply takes experimentation. Two synthesizers that perform the same operations will not produce the same sounds. You can find many free synthesizer plugins to get started!