Im a big science geek, reading pop-sci books from all fields. One thing I came across is some work on human happiness. Apparently humans have a default state of

Im a big science geek, reading pop-sci books from all fields. One thing I came across is some work on human happiness. Apparently humans have a default state of happiness, which is, 'I'm ok but I could be doing a bit better'. All humans, from millionaires to poverty stricken, are almost always in this state, a relative gain or loss will temporarily make you more or less happy but you will quickly return to this default. As an evolutionary trait it makes sense, a successful species wont be totally depressed and suicidal, or be totally blissed out, not bothering to compete for resources and mates. Also on a physiological level your body will produce a certain amount of dopamine and serotonin and other mood chemicals. The upshot of all this is that unless you are clinically depressed or have some serotonin production deficiency or some-such, then other ailments, hearing and vision impairment wont really affect your overall happiness. They will initially but then you will get used to that state and your happiness will return to its status quo level.