The term synthesizer is applied to a wide range of electronic devices, all of which are designed to imitate a natural sound. In musical terms, synthesizers are used to generate from scratch the sound of a given instrument. They can imitate the sound of a piano, a human singer, or any number of other instruments. In fact, a drum machine is also considered a kind of synthesizer. Most synthesizers used in music incorporate a keyboard to make their use more practical to a musician. For this reason, many people think of synthesizers as piano like instruments, but this can be misleading.
How synthesizers work
Synthesizers create the sound they produce by using several different methods, each specific to the instrument. Mathematical processes such as additive and subtractive processes, as well as frequency modulation, analyzes the sound spectrum produced by a real instrument and attempts to recreate this sound through synthesis. These processes depend on generators to create the spectrum and filters to manipulate it.
Another way that synthesizers produce their sounds is through a combination of sampling, again combining an approach using samples and wave imitators. The instrument to be copied is recorded in wave form, and then is played back at different speeds in order to make different tones possible.
A third way that synthesizers produce their sound is through a process called physical modeling. While mathematical processes especially are still found in all synthesizers, physical modeling is the most popular way today to have the instrument reproduce sound. The process uses the envelopes and vibrato manipulation techniques of the traditional synthesizer, but also adds an ability to actually manipulate the process that creates the sound that the actual instrument makes. This application can apply to any type of instrument, as synths that use physical modeling also include different parts for sound manipulation, including tubes to increase the air pressure if you are duplicating the sound of a trumpet, etc.
The popularity of synthesizers
Synthesizers hit their peak popularity in terms of visibility in the 1980s. They were popularized by rock and roll bands that would wear synths modeled on the sling of the guitar. When this look fell out of popularity, many people thought that synthesizers had fallen off the map as well.
This has never actually been the case, however. The incorporation of synthesized instrumentation has become a staple in most popular musical recordings. While tracks played by artists live do not include the visible strap and carry synth model of the ‘80s, synthesizers are generally present on stage disguised as keyboards or digital pianos. Most acts in today’s music industry rely on synthesizers to boost and complement the tone of their music, while some music forms, such as rap and dance, would be impossible to recognize without the use of the synth. Synthesizers are also a necessary part of the recording process, as anyone who has used a music workstation is well aware. Partnered with sequencers and samplers, a synthesizer provides vital input into the mixing process.