To make some temporal manipulation magic or superpower effects do this:

1. Make sure to have the latest version of Audacity and LADSPA (separate package in some Linux distros)
2. Generate or record noise (about 3s)
3. Effect/Fade in and Effect/Fade out beginning and end respectively (about 0.5s)
4. Generate silence (about 3s before and after the sound (so freeverb has room to operate))
5. Apply Effects/Freeverb with default settings or play around
6. Effect/Reverse
7. Repeat step 3.
8. Select the non-silen part (otherwise in the next step you'll be time-shifting silence, which would be a waste)
9. Apply Effect/Sliding time scale/pitch shift with ending time 400% and ending pitch +4 semitones.
10. Effect/Normalize (all checkmarks) -0.01dB
11. The slow down effect is done now. To get the speed up effect, just apply Effect/Reverse. Here's the result.

Protip: assign key shortcuts (I use 4-0) for normalization, fade in, fade out, freeverb, sliding ts/ps generate silence and reverse.

Try using any other sound but noise, it allows to create awesome energy/magic effects (example).

 
To the extent possible under law, Iwan 'qubodup' Gabovitch has waived all copyright and related or neighboring rights to this Short Audacity Tutorial.