WHALES have a cunning way of filtering the sound of their own 鈥渧oice鈥� out of their echolocation systems, to help them navigate and locate prey.
The 鈥渃licks鈥� that whales produce for echolocation are loud, while the echoes that bounce back are faint. Alexander Supin of the Russian Academy of Sciences in Moscow wondered how they hear the echoes above the noise of their outgoing clicks. To find out, his team placed a suction-cup electrode near the blowhole of a false killer whale (Pseudorca crassidens). This eavesdropped on electrical signals in the whale鈥檚 brain stem. The team found that the original click and the echo evoked the same strength of brain-stem response (The Journal of the Acoustical Society of America, vol 113, p 2408). So they say whales鈥� brains may suppress the sound of an outgoing click to make the echo easier to detect.