Shaping electronic sounds
There are three main stages in producing electronic music - generating current, filtering it, and amplifying it.
In the generator, a device called an oscillator gives the current its vibrating waveform. The rate of vibration (the frequency) is controlled by varying the voltage to the generator circuits. For the pure (fundamental) pitch, the wave is generated as regular loops - know as a sine wave. Other waveforms generated include square waves and saw tooth waves, which produce basic sounds and some overtones.
Various filter circuits are used to further shape the vibrating waves. Filters let through certain frequencies only, and block the rest.
They alter the quality of the sound and create different effects. Amplifying sounds is achieved by increasing the voltage to the loudspeaker circuits.
A synthesiser has a keyboard like a piano, but the keys simply change the voltage that goes to the generator circuit, and so produce sounds of a different pitch. Other knobs, dials or slides control the route through the various circuits.
To change the intensity and duration of a sound, the player operates a control called an envelope generator, which alters the way in which the voltage is applied to several circuits at the same time. A sound can be switched in suddenly and briefly, for example, or brought in with gradually increasing volume and slowly faded out.