When I play jazz/pop, I struggle to get the musical thoughts I "hear" in my head out onto my instrument. I can tell that what I've played isn't what I wanted to play, but I don't know how to correct it (other than by trial and error) to what I want it to be.
I've tried singing, and it helps: I've found that if I can sing it accurately usually I can get it out accurately. However, this has two problems: 1. my singing itself is not that accurate and sometimes I have to try several times before I get it right (I'm not a trained vocalist), 2. when I'm performing I can't stop to sing.
I've done ear training and can reliably identity single notes over a key center and do two-part dictation.
Are there ways to work around this? Is it just spending more time singing and learning how to translate my inner hearing into physical movement?