In one experiment, a group of people were assigned a task and told to get on with it in total silence. Then they were asked to complete a task while they also heard two other people having a loud conversation. They managed the tasks equally well on both occasions. But when they were played a tape of just half a conversation, their ability to perform the task diminished rapidly. I Can’t Believe You Just Said That: The truth about why people are SO rude by Danny Wallace
Makes complete sense to me, my brain automatically starts filling in the other side of the conversation. he worst part is if you cant hear the end of the conversation - it’s like turning off a movie off without finding out how it ends.