OK - maybe a basic thing here.

I'm learning about formants/harmonics, and formant extraction.

One thing I was wondering if is if there is an expected decrease in amplitude of the subsequent harmonic overtones, unrelated (somewhat) to the formants/vocal tract.

It seems like you could estimate the fundamental F0 and its approximate "un-formanted" amplitude, then, coupled with the assumed (ideal) amplitude decrease of the harmonic overtones, "subtract" this signal from the original signal to get an approximation of what the formant structures look like.

This approach seems too basic/naive, so I might be missing something conceptually, but would appreciate any thoughts on this and perhaps why it wouldn't work.

Thanks!