露脊鯨
Until recently it was thought that the most common call used by North Pacific right whales was the "upcall". This call is relatively stereotypic among all right whale individuals and populations. The next most common call has been labeled the "downcall" and this is also fairly stereotypic. Right whales also make a variety of other frequency-variable calls of different durations. However, these are so varied, they have not been categorized by researchers.