Chris wrote:
When free diving you can't equalize because
you don't have an air feed at ambient pressure.


Of course you do. Every bit of air inside you
(except for that in the unequalized middle ear)
is at ambient pressure.

Chris

You are right but it is decreasing in volume as your body is compressed.
Equalizing is normally understood to be taking new air in at ambient
pressure to equalize in your ears and lungs etc. That is why you
shouldn't hold your breath ascending after breathing pressurized air.
You'll embolize.