My son is hearing impaired and also has CAPD. I've posted on this before. It is definitely a real diagnosis.
Some examples- in the classroom, the teacher said "who likes ice cream??!!" All of the kids jumped up and down and screamed, "I do, I do." Not my son - he was sitting in the front row with his excellent hearing aid on and working and the FM system working. It was like he didn't even "hear" her. But he had to have heard her due to all of the technology streaming into his brain at the time. It's like being deaf but you aren't really deaf.