My experience is different. When free diving you can't equalize because
you don't have an air feed at ambient pressure. (Your last breath was at
the surface) Unless I am not understanding the term "free diving" which
I believe means diving without tanks. I that case the air inside your
body gets compressed as you descend and you can't equalize by taking in
more air.

Gary

Hi Gary:
Hope I can add a bit of clairity.......... when decending at 75 fps:

Using sport SCUBA
Using "hard hat" either open simi or closed demand or a free flow pot.
Using nothing but your skin (freediving).

To equalize/clear ears need to have the inside preasure abot the same
as water preasure pushing on ear drum. How to do that? With iincreasig
preasure from decent use muscles to force a presure increase. As decent
continues so does presure. And will need to eqalize ears to new and
increasing water preasure. ANalogy wold be to squeeze a balloon with
hands.
Bob