I just wanted to "revive" this post.
I am trying to work something similar myself.
Unfortunately the estimations for the formants that I get are not really good which results to a crappy output that makes no sense on the Formant synthesiser.
Could anyone please give ideas on how to get an estimation of the first two or three formant frequencies and their amplitudes as well?
LPC is almost impossible in Pd, since the documentation is really poor.
So, two ways I can think of is either using Fourier or just filtering.
Unfortunately I haven't been able to implement the Fourier transform and the filtering approach I use does not work really well..
So, ideas anyone????

ANY help will be highly appreciated!

Thank you in advance!!!