I think every author would benefit by reading their story aloud, preferably in front of someone else. The best reason is to improve dialogue. Sometimes, as I write dialogue, I hear it in my head. But when I hear it for real, with my ears, dialogue that sounded true in my head is revealed to be false to my ears. Just last night, I realized "There is no way folks would talk that way, even in 1944."
The reason you should do it to another person is to pick up on their cues, whether physical or if they interrupt you. As I read aloud to my writing group, I can see them marking something on their copy at a certain place. I make a mental note (or a literal one on my own copy) to come back to that place and see what troubled them. When I read to my wife, she interrupts me if something bothers her. It's not always something she can explain. But, if it bothered her, it will bother a reader I don't know. So, I fix it.
Sometimes, as I'm reading aloud, my brain and mouth will actually fill in some gaps with words not on the printed page. I pay special attention to those times and actually mark my copy with the words I just spoke. If I say something that feels natural in my mouth, then I should have my characters speak that way, too.
This one may sound corny but it comes from my long association with audiobooks: change your voice. Not every author has a voice good enough to read his/her own work as an audiobook. But when it's just you and a small group or a spouse, go ahead and change your voice. Sure, men will sound funny trying to make their female characters talk but changing your voice will get you into those characters better. If you're making an effort to make, say, a Texas character sound like a Texan, give him an accent. Then, as you write the Texan's later scenes, you'll be able to 'hear' how he sounds and write truer dialogue. I do, at least. And then, after you've established that the Texan sounds a certain way, give some clues in your prose to the way the character sounds. That is, have one character comment/think about how the Texan sounds. It'll liven up the voice in a reader's head.
Lastly, if you don't have anyone to read to, record yourself. You may cringe at your own voice but you will be able to hear your story from a source that is not your own brain. It helps. I've done it.
- Read aloud to improve dialogue
- Read to someone and pick up on their reactions
- Record yourself reading your story and study how your voice flows over passages
- Make notes on your draft if you find yourself filling in words that are not on the printed page
- Change your voice to match the characters