Whales produce upcalls, sometimes called contact calls, when they are alone or in the process of joining with other whales. An upcall begins low and rises in pitch. It is the most frequent call produced by right whales.
Parks and her colleagues, Mark Johnson and Peter L. Tyack, Woods Hole Oceanographic Institution and Douglas Nowacek, Duke University, looked at short-term modifications of calling behaviour of individual North Atlantic right whales in varying environmental noise situations. They report their results in Biology Letters.