Can confirm ^. Even as someone who grew up with hearing aids, playing music and using the phone, my cochlear implant being turned on for first time sounded like being in a warehouse full of R2D2 droids all beebooping the 90s modem dial-up sound at the same time. The brain is unable to comprehend these new signals right away, so it took a few hours before those beebooping sounds started to morph into something discernible, like someone speaking in 8-bit quality. Those softy heart-filling videos of babies smiling or people going into tears / being proposed to is not a true representation of what C.I. is like when being activated for the first time.

As weeks go on following activation, the brain's had more time to study the signals and figure out what to do with them, and eventually people's voices start to make sense. It wasn't until six months in when I was able to make my first phone call, and close to a year when music began sounding very nice. This is why it is absolutely critical that cochlear implant users wear it all day, every day, so that the brain is able to work on sounds full time.