this is more of a general DSP question...

i am working on an LPC playback and mangling system for axoloti. i have most of it working and i am now trying to shift formants in the filter to change voice character. i found functions to convert reflection coefficients into polynomial pairs and presumably i should be able to shift filter frequencies in this representation of the data. unfortunately i have no clue how to do that. any hints, papers, code snippets etc. are very welcome.

or if someone wants to take the time to explain, you are of course more then welcome

thanks for any suggestions