When I looked at Pavarotti's voice on a spectrogram, it almost always have the strongest peak at H3 (third fundamental), sometimes even from as low as a C4, so it's not only on notes at or past his passaggio. I then did the same analysis for a few other well-known tenors and most of their voices also exhibit this behavior.
When I looked at my voice I noticed that H3 is the strongest at lower notes, but once I hit B3 H2 starts to dominate H3, the higher I go the weaker H3 becomes. Granted I am a baritone but I can't seem to carry the stronger H3 through my passaggio, so I wonder if there is any physiological adjustment in my vocal tract I can do to make H3 stronger? I want to improve my resonance from this perspective. Thanks!