I should clarify - I've also had some pretty remarkable results (although, speech on the second day? Wow!). I did notice significant improvement quickly after activation, and my hearing is already much better than it was with hearing aids before the surgery. But I also know that it's not as good as it was several years ago (say, 5 years, just for the sake of pinning a number to it). That's not such a big deal; but it does suggest that 5 years ago (or for someone without a progressive loss who has heaering like I had back then), a CI would not have been appropriate, because I got equal or better benefits with hearing aids Obviously, I haven't hit the limit on assimilating the CI into my sense of hearing, so this is more of a thought exercise, but ... yeah.
