Fred Cummins is a cognitive scientist from UC Dublin who among other things works on joint speech.

"Joint Speech is speech produced when one or more people say the same thing at the same time. This kind of speaking is commonly found in practices of prayer, in protest, and on the terraces of football matches. It is found in classrooms and courtrooms. To those who take part, it is a very important kind of activity. Yet it has hardly been studied from a scientific or empirical point of view at all."