Timestretching audio became a household term with the advent of Akai’s S-1000 sampler in 1988.
A special feature in the sampler allows you stretch out the duration of the sample by adding extra samples that are interpolated values in between the original samples. This gives quite a dramatic and robotic effect, that was widely used in the late 1980s and early 1990s.
But there is plenty of mileage still in this sound generation technique. A good example is a small Mac app called “PaulStretch”, which enables you to stretch things to ridiculous amounts. A simple word, such as “goodbye”, can be stretched and evolve into a symphonic wash of sound that is interesting and quite pleasant to listen to.