Why has the voice in my head perished?

No it sounds like you have a talent that needs to be nurtured before it will bloom. I'd set my sites on college and a degree that will tap that talent. All of the greats only became great when they had had the time to nurture and hone their talent. You're only 17. Between now and 30, I recommend that you focus on learning as much as you can about your field of interest. Then practice, practice, practice because practice makes perfect. (or close to it anyway)