If you have a quiet group, it can be hard to imagine. But yes, on some teams, everyone wants to speak up at the same time! What’s a facilitator to do?
Use a Talking Stick
Pick a distinctive object to be your Talking Stick (I’ve used sticks, bean bags, balls, and many other things). Set a ground rule that only the person holding the talking stick is permitted to speak. If someone else in the group has something to say, instruct them to simply raise their hand and be patient. When the person with the Talking Stick is finished speaking, have them hand the Talking Stick to someone else who has their hand raised.
Maintain a Speaking Stack
The problem with the Talking Stick approach is that it can be frustrating if you’ve had your hand raised for a long time but no one is handing you the Talking Stick. That’s why I recommend complementing the Talking Stick with a Speaking Stack.
To maintain a Speaking Stack, simply assign a number to everyone who has their hand raised. Louise, you’re up first. Jane, you’re next. Mark, you’re third. When Louise finishes speaking, have her hand the Talking Stick to Jane and move Mark up from third to next in line. Add anyone else to the Speaking Stack who raises their hand. And so on.
By maintaining a Speaking Stack, people will feel less inclined to interrupt others in the retrospective.
(“A Talking Stick” flickr photo by Ind3rjeetKaur https://flickr.com/photos/maisometimes2/4334154780 shared under a Creative Commons (BY-SA) license)