I am wondering if anyone has done any work with formants using teensy? I would like to experiment with processing formants separately from the fundamental frequency content. For example, this can be used to create a gender knob by pitch shifting the formants alone. This is done in a few products such as the TC-Helicon VoiceTone C1 (very cool product). I have done some research but it is a pretty niche topic and while I have found mentions of formant filtering, I have yet to find details on an implementation.