Q: How to prescribe the gain of a hearing aid ?

[xiaoxianbo]

According to audiogram, we prescribe the gain at several key
frequency, that is the base of our frequency fitting. So how to do
that?

I have heard some words like 'gain between one-third and one-half of
hearing loss', and some methods like, Berger, NAL, POGO, Libby,
Keller. are those the formulae implimented in practice? how to do ?
what is the detail?

Hope to get your help.