QUESTION: My critique partners say most of my characters sound alike in dialogue. Help!
Cast all your characters with actors you are very familiar with so you can hear their voices when you write dialogue. Unless you have a tin ear for speech, you will rarely have two characters sound alike.
When you pick your actor, consider what part of the country or country of origin your character is from. Make sure their voices reflect that. You don’t want an actor from DOWNTON ABBEY to play a cop from Philly.
Writing dialogue as what it sounds like rather than the proper spelling is frowned upon these day unless used very sparingly so don’t go overboard with phonetic spelling ("Yo' ole father doan' know yit what he's a-gwyne to do. Sometimes he spec he'll go 'way, en den agin he spec he'll stay.”--from HUCKLEBERRY FINN) or apostrophes to show words that are slurred together. (“If’n you think, I’s stupid. You be wrong!”)
If you aren’t that familiar with a region’s speech, be very careful how you write it because it’s easy to stereotype or get it wrong. For example, most of us in the Southern US don’t use “y’all” that often, and when we do in very informal speech, it’s plural meaning more than one “you.” (Jennifer turned to her cousins and smiled sweetly, “Y’all come home with me and have some supper.” Her voice turned frosty as she glared at her brother. “You don’t come, period.”)
You should also consider social class and education. Someone with a college education and an upper middle class background won’t sound the same as someone who never finished high school whose parents never finished high school.
Read your dialogue aloud or in your head to see if you’ve got different voices, or ask a few friends or family to read your dialogue like a play to see how it sounds.
Another good test is one line of dialogue that isn’t attributed to who is saying it. If a reader can tell who is saying it by how and what is said, then you’ve succeeded at your task.