If you can't play it, you can't hear it. I have a student, and incredible singer, but can't play anything. All is done by hear, quite incredibly. The best proof to what you are hearing, is to be able to play it. If you don't have the physical correctly ingrained in the mind, nothing can be proven correct. It's backward logic or deconstructive logic. An example, if you are a beginning mechanical dart player and can't add, you're in trouble. One must know how to throw, first. Next, one needs to be able to add three or four fold to win or keep your bets. Two different skills and two different learning skills.

It's certainly OK, to say "play what you hear.", but it's entirely another to prove it. I've read many items on this forum the bear me truthful. Music is a listening art with many and more asundries. The bulwark of our art as guitar players, is listening and then the physical. Most of us, are not singers. Singing your scales and bass cycles (chord progressions), is "life" for a productive and prosperous living. My student came to me with the admission of finally understanding my point. "Lightbulb moment." To prove what you hear is true, be able to play it. To prove "you" are not in error, play it.

I cannot stress enough, horrible singer or not, sing everything!! you attempt.