When I'm reviewing stories, I try to make sure I listen to my characters, that the words I've given them I can actually "hear" them saying, that nothing is inappropriate or out of kilter for them. I do speak work out loud, especially dialogue. Sometimes I record myself and play it back. Ignoring the fact I tend to sound posh on any kind of recording device, I find playing dialogue back is the sure way to pick up any thing that does not ring quite true or if what looks right written down is actually tricky to say out loud. I try to stick to the Keep It Simple, Stupid principle for writing dialogue. It works.
I listen to the story as a whole too as part of my editing process. The story has to ring true on all levels and "hearing it" helps this.