Digital Sound & Music: Concepts, Applications, & Science, Chapter 6, last updated 6/25/2013
operations on them to alter their shapes. The
user controls this process by knobs, dials,
sliders, and other input controls on the
control surface of the synthesizer whether
this is a hardware synthesizer or a soft synth.
Under the hood, a synthesizer could be using
a variety of mathematical methods, including
additive, subtractive, FM, AM, or wavetable
synthesis, or physical modeling. We’ll
examine some of these methods in more
detail in Section 6.3.1. This method of
creating sounds may not result in making the
exact sounds of a musical instrument.
Musical instruments are complex structures, and it’s difficult to model their timbre and
amplitude envelopes exactly. However, synthesizers can create novel sounds that we don’t
often, if ever, encounter in nature or music, offering creative possibilities to innovative
composers. The Subtractive Polyphonic Synthesizer from Reason is pictured in Figure 6.19.
Figure 6.19 Subtractor Polyphonic Synthesizer from Reason
In reality, there’s a good deal of overlap between these two ways of
handling sound synthesis. Many samplers allow you to manipulate the samples
with methods and parameter settings similar to those in a synthesizer. And,
similar to a sampler, a, synthesizer doesn’t necessarily start from nothing. It
generally has basic patches (settings) that serve as a starting point, prescribing,
for example, the initial waveform and how it should be shaped. That patch is
loaded in, and the user can make changes from there. You can see that both
devices pictured allow the user to manipulate the amplitude envelope (the ADSR
settings), apply modulation, use low frequency oscillators (LFOs), and so forth.
The possibilities seem endless with both types of sound synthesis devices.
Synthesis Methods 6.1.7
There are several different methods for synthesizing a sound. The most common method is
called subtractive synthesis. Subtractive synthesizers, such as the one shown in Figure 6.19, use
one or more oscillators to generate a sound with lots of harmonic content. Typically this is a
sawtooth, triangle, or square wave. The idea here is that the sound you're looking for is hiding
Aside: Even the term analog synthesizer
can be deceiving. In some sources, an
analog synthesizer is a device that uses
analog circuits to generate sound
electronically. But in other sources, an
analog synthesizer is a digital device that
emulates good old fashioned analog
synthesis in an attempt to get some of the
“warm” sounds that analog synthesis
provides. The Subtractor Polyphonic
Synthesizer from Reason is described as an
analog synthesizer, although it processes
sound digitally.
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