This category includes effects that affect the propagation of a sound. Some people would call these time-based effects, which is not a bad idea. It helps avoid confusion, as there is an actual specific effect that is called delay. These are the audio effects which I personally have the most fun playing with.
All the effects below have sample clips, each containing a dry/clean/unaffected take, followed by another take with the effect applied.
Flanging involves mixing a signal with a slightly delayed (up to 10 milliseconds) copy of itself, albeit processed through a low frequency oscillator (LFO). We’re not going to get into the details regarding the LFO, but it is responsible for the swooshing sound characteristic of flanging and other similar effects.
Flange effect over a distorted guitar riff
A chorus is similar to the flange effect, but with a slightly longer delay time (10-50 milliseconds), resulting in a richer or sweeter sound (I personally don’t like using either terms). Its character leads some people to regard chorus as a doubling effect in certain instances.
Light chorus that mimicks the sound of two guitars playing in unison
Also similar to flanging, but employs a series of frequency filters before letting the signal go through an LFO. This results in a distinctly different sound compared to a flange or chorus effect.
Slow and subtle phaser
A more pronounced phased sound.
A delay effect takes a signal and plays it back after a determined period of time.
Delay effect that loses high frequencies after each repeat (popularly referred to as an analog delay)
Reverberation occurs when sound reflections off one or more surfaces blend together, simulating a feeling of a particular space, whether it be a small room or a large hall. This is also regarded by some people as a very fast delay.
Simulation of reverberations in a large hall
Much like with the case of dynamics effects, the general guideline for these is to apply them during post production rather than directly to the live sound while recording. With a clean original recording, you have the benefit of tweaking, replacing or adding to the effect. Whereas if you record an effected sound, you’ll be stuck with that, at least until you record another take.