Sound waves are often simplified to a description in terms of sinusoidal plane waves, which are characterized by these generic properties: Frequency, or its inverse, wavelength. Amplitude, sound pressure or Intensity. Speed of sound. Direction.   Audio oscillator Featured snippet from the web Oscillators generate sound by, er, oscillating.Â
That is, their circuitry basically changes or oscillates between two states very quickly, and just as a vibrating string produces a sound, so the oscillating electronic circuit generates a waveform that can be amplified and used as a sound source.   #HowSynthesizersWork     BY JEFF HARDER #Synthesizer Components   Jay Blakesberg/Workbook Stock/Getty Images Jay Blakesberg/Workbook Stock/Getty Images WHAT MANY MUSIC BUFFS THINK OF WHEN THEY HEAR THE WORD "SYNTHESIZER."Â
Even though many synthesizers possess the ebony and ivory keyboard of a piano, the rest of the machine -- a chassis lined with knobs, dials and switches -- looks more like it belongs in a garage instead of a concert hall. Nonetheless, the synthesizer contains the same two components as almost any other instrument: a generator and a resonator. Think of a violin, for example: the strings and the bow are the generator, and the body of the violin is the resonator [source: Rhea]. Â Â On a synthesizer, the generator is the oscillator, and the resonator is the filter. Â For starters, let's look at the basic parts of a classic analog synthesizer. (We'll talk about digital synthesizers later.) Analog synthesizers generate their sounds by manipulating electric voltages. The oscillator shapes the voltage to produce a steady pitch at a given frequency, which determines the basic waveform that will be processed elsewhere in the synthesizer. The oscillator can be controlled by the keys similar to a piano keyboard, a revolving pitch wheel or another tool on the synthesizer's interface. The oscillator feeds the signal to the filter, and the musician turns knobs and dials to set parameters around the frequencies of a sound -- for instance, eliminating and emphasizing specific frequencies like we talked about earlier. The sound passes from the filter to the amplifier, which controls the volume of the sound. The amplifier generally includes a series of envelope controls, which help determine the nuances in volume level over the lifespan of a note. Â In an analog synthesizer, each of these pitch, tone color and loudness functions is organized into a module, or a unit intended for a specialized purpose. The earliest modules were encased in their own individual housings. Each module creates a particular signal, or processes it in a particular way, and by connecting these modules together, the musician can layer, process and change the sounds into something different. Â Now that we know about #howsynthesizerswork, let's look back at their history. Â Â Â History Long before the invention of electronic signal processing, some people tried to build machines to emulate human speech. Some early legends of the existence of "Brazen Heads" involved Pope Silvester II (d. 1003 AD), Albertus Magnus (1198â1280), and Roger Bacon (1214â1294). Â In 1779 the German-Danish scientist Christian Gottlieb Kratzenstein won the first prize in a competition announced by the Russian Imperial Academy of Sciences and Arts for models he built of the human vocal tract that could produce the five long vowel sounds (in International Phonetic Alphabet notation: [aË], [eË], [iË], [oË] and [uË]).[5] There followed the bellows-operated "acoustic-mechanical speech machine" of Wolfgang von Kempelen of Pressburg, Hungary, described in a 1791 paper.[6] This machine added models of the tongue and lips, enabling it to produce consonants as well as vowels.