Everyone one of those CI recipients (or their parents) knew there were no guarantees on how the implantation will turn out. They understood this from their audiologists, surgeons, and doctors. No one was told that getting a CI they will find themselves suddenly able to hear and understand the spoken language right away. the CI recipients (and/or parents) knew it would entail work and adjustment to sound over time. That's dependent on a few things such as using a hearing aid while growing up or were once a hearing person but became deaf later on in life. Another factor is what age did the implantation take place, the earlier the implantation the greater chance of success (provided they get supportive therapy along the way). One of these factors help ensure the successful use of CI. This is so true in getting a CI at a critical period during their brain development to take advantage of the auditory cortex to make sense of any auditory input. Any delay, say a hearing child who completely loses his hearing at age 3 and doesn't get CI until age 5 or 6, will likely not see a successful use of their CI and may discard it later on in life. In one case, there were two children in Australia who received the world's first multi-channel CI. Both were hearing until age 3 when they lost all hearing due to meningitis. One didn't get a CI until age 5 and the other one didn't get the implant until age 10. Both ended up not using the CI fulltime because the delay (2 years and 7 years) caused them to lose all auditory skills, phonological knowledge, and receptive and expressive language skills. The implantation occurred beyond the optimum critical period of their brain development and auditory cortex. They eventually rejected fulltime use of CI during adolescence. This was during the middle 1980s when it happened (the implantation).
Those who received their CI and later on don't use it took a few years to several years or more before making the decision to stop wearing it for whatever reasons. The percentage of partial or non-use of cochlear implant ranges between 1 to 10% of the total CI population depending on the age.
(The Oxford Handbook of Deaf Studies, Language, and Education. Volume 2. 2010).
