I’ve asked my all-Deaf/HH students a similar question several times over the years and get a variety of answers each time.
The question I ask is more of, “How do you communicate in your dreams,” and most of the answers fall in three broad areas: through speech, through sign language, and telepathically. I communicate telepathically in my dreams and don’t hear anything.
The students who say they speak in their dreams have said both… they hear normally as if they’re not deaf, or they use speaking and not actually hearing speech, but still understanding spoken dialogue.
Most of my students say they don’t hear in their dreams, but almost all say they understand communication regardless.
There doesn’t seem to be a set pattern or correlation- like “if they heard before, then they hear in their dreams” – it’d be easy to assume that would be true, but that’s not really what happens.
I find this question intriguing enough that I ask it regularly!