When most of us listen to music, we hear more or less the same thing. But not everyone. There are people who have extra-sensory abilities to hear what other cannot, and they're others who either can't, or can, but simply don't enjoy it.
Cochlear implants can improve not just hearing, but cognitive function, in older patients. They have also helped toddlers with impaired or absent hearing to learn to speak normally, if utilized at an appropriate age, between 12 and 18 months.