Waveforms: The shape (pattern) of the frequencies generated by the oscillator. They are distinguished by the harmonic partials present. The most basic shape is the sine wave, which consists simply of a single frequency with no overtones. (It is called a sine wave because this is the shape of the graphical representation of the air displacement of vibrations). Because of its purity the sine tone has been of interest to composers using electronic modification devices such as a ring modulator, where two single frequencies are required as inputs. Also to be able to create complex tones via superimposition, control over single frequencies is required. Sine Tone generators were vital components of the classical 50's electronic studio. A square wave consists of only odd-numbered partials. Also the higher the partials present the less the amplitude. The pulse wave has all the harmonic partials at equal amplitudes. When a filter is applied, the amplitude of the overtones do not decrease when the particular frequency area is moved further away from the fundamental tone. Here are the classic oscillator wave shapes: