I have written about my making of a series of sreencasts of basic sound synthesis in puredata in an earlier blog post. The last addition to the series is the building of a patch that shows how a simple impulse response, combined with a delay, a feedback loop and a low pass filter, can be used to simulate reverberation. In fact, dependent on the settings, this patch can also be used for making phasor, flanger, chorus and echo as well.