I don't know of any existing convolution plug-ins for Audacity, though it should be possible to make one using Nyquist. There are nyquist functions "snd-convolve" and "convolve" available in the Audacity implementation of Nyquist.
(snd-convolve sound response)
Convolves sound by response using a simple O(N x M) algorithm. The sound can be any length, but the response is computed and stored in a table. The required compuation time per sample and total space are proportional to the length of response. Use convolve instead
http://www.audacity-forum.de/download/e ... t6.html#53
(convolve sound response)
Convolves two signals. The first can be any length, but the computation time per sample and the total space required are proportional to the length of response.
Convolution is usually used to create reverberation effects, but is usually much less efficient than other types of reverb. G-Verb and FreeVerb both provide useful and effective reverb effects.
[Edit] There is a LADSPA impulse convolver available from here: http://plugin.org.uk/ladspa-swh/docs/la ... tml#id1199
(see the top of that page for the download link).