What happened when the doctor turned on August hearing aids?

From the text:

How can I describe what I heard when the doctor turned on my hearing aids? Or what I didn't hear? It's too hard to think of words. The ocean just wasn't living inside my head anymore. It was gone. I could hear sounds like shiny lights in my brain. It was like when you're in a room where one of the lightbulbs on the ceiling isn't working, but you don't realize how dark it is until someone changes the lightbulb and then you're like, whoa, it's so bright in here! I don't know if there's a word that means the same as "bright" in terms of hearing, but I wish I knew one, because my ears were hearing brightly now.