Is anyone aware of any good Pd processes or patches for pitch analysis of a polyphonic signal? I know this is a notoriously tricky issue, and that there are FFT patches and objects like fiddle that handle monophonic analysis well. I have to identify some exact frequencies within a piece of microtonal music which contains drums etc.

have not used this...
http://grrrr.org/research/software/cq2midi/

http://patchstorage.com/chordetector_pd/

Thanks for these suggestions. I'll give them a try