there is absolutely no rupa in the arupa Brahma realms - thus those beings can’t see, hear , taste , touch or smell, so unfortunately they can’t hear the Dhamma.
People wonder how there can still be mind if there is no heart base. We discussed this:
There is a sixth vatthu which is not one of the pasada-rupas. This is the hadaya-vatthu or heart-base. The hadaya-vatthu is a kind of rupa which is the place of origin for the cittas which are not among the panca-vinnanas (seeing, hearing, etc.) since these cittas have the pasada-rupa as their place of origin. The hadaya-vatthu is different from the mind-door. The mind-door is a citta, the bhavangupaccheda-citta, which is the last bhavanga-citta arising before the mano- dvaravajjana-citta (mind-door-adverting-consciousness).