Scientific pitch notation creates a linear pitch space in which an octave spans 12 semitones, where each semitone is the distance between adjacent keys of the piano keyboard. Distance in this space corresponds to musical pitch distance in an equal-tempered scale; 2 semitones being a whole step, 1 semitone being a half step. An equal-tempered semitone can also be subdivided further into 100 cents. Each cent is semitone or octave. This measure of pitch allows the expression of "microtones" not found on standard piano keyboards. The notation is sometimes used in the context of meantone temperament, and does not always assume equal temperament
Octave effect performances. Hendrix used an octave-fuzz pedal known as the octavia. Analog octave effects differ from harmonizers and pitch shifters which digitally sample the sound and process it to change its pitch. Octave-up effects usually use full wave rectification using diodes to "fold up" the negative part of the waveform to make a new waveform an octave higher in pitch. Octave-down effects are typically produced by converting the signal to a square wave, and then using flip-flop circuits to divide the frequency by two. This creates a buzzy synthesizer like tone. The MXR Blue Box used this method to create a