QuasiUnaFantasia Funny observation: I am studying a short sample of a chord (played using the Steinway B piano from Ivory II, not that it matters), and it turns out that the single frequency with greatest importance is 12.29 Hz. The lowest key, however, has a base frequency of 27.5 Hz ...
Perhaps that's a beat, rather than a partial?
dore_m Yes. Many times the fundamental is not the loudest partial.
This is always the case for the lowest range of the piano, where the second or third harmonic is louder than the fundamental. But what @QuasiUnaFantasia is reporting here is more dramatic: a frequency lower than the lowest possible fundamental for any note.
The only explanation I can think of at the moment (2 minutes after reading it and without thinking it hard) is that it's a beat.
Because those who came before us did all the simple stuff and left us with the hard things….. it's gonna be even harder for our greatgrandkids….