At 4,000 hz, I believe there are no CIC’s that can produce enough gain and headroom to match your hearing loss. Many BTE hearing aids (not including open fit) would also be pushing pretty hard to meet the gain needed at 4,000 hz. Yet, in reality, that area may actually be a cochlear dead spot, and amplifying beyond 3,000 or even 2,000 hz may possibly not even help anyway.
There are ways for your audi to help detect these problems and to determine if amplification in these areas are really helping or not.
If not, then staying with CIC’s from most brands should be fine. Yet, if amplifcation at 3,000 and 4,000 hz are helping you with speech discrimination, then a more powerful aid may be best.
I use the Phonak Micro Power series, which incorporates a small BTE with a very thin wire and a speaker that is housed in a custom made CIC case with my customers. It is almost as invisible cosmetically, yet we have the power performance, with high gain and output.
I believe I posted some pics earlier this year…try doing a search on this forum. If you can’t find any, please post and I will post some pics of the actual product on our customer’s ears.