That climbed to 99.6 percent for 10 clicks and 99.9 percent for 20 clicks. Dougherty also refined a side benefit to the process. He can acoustically measure the size of a whale. The big, blocky head that is the sperm whale's trademark feature contains a large cavity filled with about 500 gallons of oil. When a click is produced, the sound echoes within that chamber.
Researchers can measure the echo time and deduce the speed at which sound travels through the oil.
That allows them to figure out how large the cavity is. From there, it's a simple matter to calculate the size of the whale. Dougherty plans to return to Norway soon to gather more data. He wants to test his process on a larger group of animals and some questions still need to be answered, such as how the whales' signals change during the duration of their dives. He's also constructing and testing acoustic buoys, which could listen for sperm whales and send data to land-based labs, making monitoring easier and less costly.