hello Jef, the -3 octave will be the cellular/blood octave for most men. But to my knowledge we do not pick up good below 50hz, even if we have mics that go lower.
I cannot say much more. Only from my EEG research with voice, I can say Delta waves are biochemical, because when I did EEG I did see biochemical changes when we did cranioSacral therapy on kids with cerebral palsy and others.  Also color and light would enhance Delta waves,light treatments with prisms also, so they relate to light biochemical issues, I have much proof of this in the EEG sessions I have done for years.  You just place electrodes and intensly look at the monitor screen or a TV screen and Delta waves rise up a lot. Delta waves are also active in dream states.
hope this helps,
love
Marysol