Time-based effects

The theory behind it

A sound can be created and changed by adding other sounds and frequencies into it. Certain parts of the waveforms' crests and troughs support or cancel out other frequencies and color the sound when added. This basic idea was developed further by taking a copy of an original sound and adding it to itself, but shifting it in time by very small degrees. As two similar waveforms play, separating their playback by various number of milliseconds creates different kinds of effects.

Different kinds of effects

If you play back the sound with itself and increase the number of milliseconds between them, you'll pass through phasing, flanging, and chorusing. Phasing is a subtle effect, flanging a bit more metallic and aggressive, and chorusing can go from subtle to nerve-jangling. One can vary the amount of effect, how much of the signal gets fed back to the input to be re-processed, basic length between playbacks, and how much the original is altered in playback, and possibly other options.

Separating playback of the copy with the original by more than 10 milliseconds begins to be perceived as an audibly separate impulse, giving rise to the effect of delay. Here one can vary the loudness of the echo, how many echoes are created, the acoustic qualities of the echoes as they change, and basic length of time. Multiple repeats and combinations give rise to reverberation. Reverb recreates the sense of a room's acoustic ambiance and characteristics and is a very complex concept, resulting in a wide selection of effect devices with a wide price range, quality and options increasing as you pay more.

In original recordings from the early days of rock, guitarists would use spring-based reverbs in their amplifiers which would break up the sound and move the springs, resulting in different lengths of the sound's waveform being created and a more complex acoustic quality. Drummers would play recorded in stair wells to use the natural reverberant qualities of that space. Vocalists would have playback directed through heater duct work to enhance the recorded sound. Tape-based devices that continuously recorded and played back through a movable recording head gave sonic options to acoustic recording and playing artists of the 1970's.

Digital technology has vastly changed this corner of the effects world. These days, we record in legendary halls and cathedrals and analyze the reverberant data to create virtual recreations of the acoustics within, putting our performances in any any venue we choose.

Digital technology has also given us a more precise and vastly easier interface for dealing with sampled sound. This has opened up all new performance possibilities and has created a new aesthetic of its own.