The learning curve is entirely up to you. How much you are prepared to do to improve how your brain and the CI work together. Some folks I’ve talked to didn’t push their learning past the first weeks or didn’t seek other voices, use the TV, listen to audiobooks etc. and so they are unhappy with their CI. Others worked like I did - pushing themselves and those around them to work that brain and train it to hear with the CI.
I worked every day, twice a day for 45 min each time for the first 8 months. I still work with a music app for Cochlear to refine my instrument identification skills and with Angel Sounds for speech in noise etc.
At first everyone sounded like Elmer Fudd. I was so astonished to be able to understand them that it didn’t bother me - did make me laugh sometimes in those early days. I worked with lots of different people of varying registers of voice, speaking styles, accents… so that my CI hearing was always challenged. My grandson did FaceTime with me and his kid voice saying words off a list was really a challenge.
You see, I couldn’t understand speech at all. I was a stellar face and speech reader so I “got by.” My CI gave me speech understanding - I can go to movies, listen to music, understand my grandkids, understand guys with deep voices and mumbly diction… I was willing to work my non-existent fanny off for any improvement while at the same time being happy to understand at all.