I used to try this with my manager when he would interrupt me. Sometimes we would go on talking over each other for a full 10 ish seconds. That's a really really long time for two people to talk over each other and not stop. So uncomfortable, but I found it so rude for him to talk over me and he did it so frequently that in the end I just refused to stop talking. I'm naturally shy and soft spoken, so it's not that I was going on too long! He never seemed to get the message, so I left. But I burned out at that company and have never been able to care about my job since. Now I hate everything about my job and can barely be bothered to touch the keyboard, that's what it has been like for the last 4 years.