Hard truth time on writing disabilities:
Unless you have first hand experience, assume everything you know is false.
Unless you have first hand experience, assume everything you know is false.
So much of the common knowledge out there is not based on facts, and many come from a very ableist perspective. In order to do things correctly you have to assume that what you've been taught is false, so that you can uncover the truth.
And you cannot simply go to medical sources. Medical sources often view disability as a negative, as a thing to be fixed, and in many cases this differs drastically from the individual experiences of living with said disability.
You also need to check yourself. Instead of comparing your world filled with sound to one without it and oh, how sad, consider never knowing sound in the first place, never having it hold any sort of special meaning. In other words: you can't look at things through ableist eyes.
That's just one example, insert any disability into the equation. And take into account onset of disability, childhood and upbringing, all of this have a huge effect on the character and how they view themselves and their world.
This is not easy, but it is vital for accurate representation. And it should be the basic simple first step taken.