"A good reader has a mind’s ear."
The first chapter of Ursula K. Le Guin’s Steering the Craft is about the sound of writing. I very much liked this quote:
A good reader has a mind’s ear. Though we read most of our narratives in silence, a keen inner ear does hear them. Dull, choppy, droning, jerky, feeble: these are faults in the sound of prose, though we may not know we hear them as we read. Lively, well-paced, flowing, strong, beautiful: these are all qualities of the sound of prose, and we rejoice in them as we read. And so good writers train their mind’s ear to listen to their prose–to hear as they write.