Additive Synthesis

Additive Organs

Additive synthesis is undoubtedly one of the oldest and most researched types of audio synthesis. Its roots date back centuries to the creation of the first church organs. The register stops, and the keyboard controls the mechanism in organs. Pressing the keys on the keyboard and pulling various register stops in different positions releases the air into the pipe. One more example in more recent times would be the old Tel-harmonium synthesizer (1906), which combined the sounds of a larger number of generators in order to create an additive tone. The instruments above were costly, so only when computers took their rightful place in the technological world did the additive synthesis method become more accessible to users.  

The Advent Of Software Synthesis

Due to their complexity, few hardware synthesizer manufacturers were willing to create additive synthesizers. But with the advent of software synthesis, many offer a fantastic variety of sounds. The theory behind additive synthesis is that nature makes sounds with many simple sine waves of varying frequency and amplitude. These are all created by the vibrative properties of the object that is producing the sound. Some of these waves might have a harmonic relationship to a fundamental tone. We hear these sounds with a definitive pitch, while others don't, and we hear them as noise. In reality, most complex sounds can contain both harmonic content and noise.  

The Theory

French mathematician Joseph Fourier theorized that you could break any sound into a series of simple sine and cosine waves. Therefore, any sound can be recreated by calculating the correct frequency and amplitude of waves. This inspired additive synthesis, giving the synth program access to sound's most basic building blocks and the potential to create any sound.  

Analog and Digital

Traditionally, hardware-based additive synthesizers have up to 6 oscillators. They use them as sound sources; each oscillator has one or two associated envelope generators. While a wide variety of sounds is possible with 6 oscillators, the reality is that nature creates sounds made of hundreds, if not thousands, of waves. So, the sound produced by analog synthesizers doesn't necessarily sound natural. However, they allow greater flexibility for the tone to evolve more naturally than the subtractive synthesizer. By using digital oscillators, modern computers, with their processing power, can mix thousands of simple sine waves in real time and, by doing so, create very complex waveforms.  

Additive Synthesis in Relation to Others

Re-synthesis is closely related to Additive synthesis. With this method, the sample is loaded into the synthesizer, analyzed, and broken down into constitutional parts. U can use these waves and envelopes as a starting point. This is done to create new sounds rather than starting from scratch. As its name implies, additive synthesis is the opposite of Subtractive synthesis. Additive synthesis never achieved the popularity of other synthesis types for two main reasons:

1. You need to have some knowledge of physics in order to create the sounds effectively with this technique.
2. Building up complex sounds with many oscillators and envelope generators is time-consuming.