Quote from Meredith Sue Willis, on her Resources for Writers page:
Grace Paley once said in an interview, “I’m an ear believer–I think the ear is smarter than the eye. The experience of reading your work aloud in a class carries you back to that original impulse, ‘I want to tell you something.’ ‘What did you want to tell me? Tell me.’ When you tell a story, it’s your voice telling a story. You really can hear what’s wrong with it. People think you can just sort of smear over it, but that’s not true. What I’m trying to do is to remind students they have two ears. One is the ear that listens to their own ordinary life, their family and the street they live on, and the other is the tradition of English literature.”
I find reading your writing out loud makes a difference too. You can hear things with your ear that you don’t pick up by just proofreading with your eyes alone.