Help finding resources about frequencies or similar

Hello, I’d like to know where I can find resources to learn about frequencies, EQ, speech and similar for fitting purposes

I’m using phonak naida Paradise p90 I bought from ebay and programmed myself with phonak target and noahlink wireless using a discreet photo of costco audiogram because didn’t want to share If I don’t buy there so I took a picture.

Thanks for your replies

Maybe taking some educational opportunities here would help?