Beluga Whales

Beluga whales live in the world's cold northern seas, where they endure months of [perpetual:permanent] darkness. "So they have to use sound, rather than sight, in order to find their way around." That's Aran Mooney, a marine [biologist:scientist] at Woods Hole Oceanographic Institution, in Massachusetts. He says belugas have really fast hearing, too: "Sound underwater travels five times faster than it does in air. And so those guys have to basically [perceive:discover] and utilize sound five times faster than we do."He and his colleagues traveled to Bristol Bay, Alaska, to test belugas' hearing in the wild. They [captured:taken] seven belugas for routine physicals. And played them a series of frequencies, while measuring the whales' brain activity with electrodes. Turns out the whales' hearing was sharp, and similar to that of captive belugas. Which means they could [appreciate:congratulate] sound ranging from about 4 kilohertz to 150 - a frequency nearly eight times higher than the upper limit of our ears.