Whales are singing a lower shade of bass

Blue whales are sounding a bit different than a couple decades ago.

A study published recently in the journal Endangered Species Research found call of the blue whale has dropped by more than half an octave.

Researchers discovered the change when they kept having to rewrite a computer program that identified the blue whales' call. They kept having to change the program to find the call at a lower frequency. Scientists then compared the current blue whale call with tapes recorded by the Navy forty years ago and noticed the blue whales' sound had gradually changed.

John Hildebrand, an oceanographer at the Scripps Institution of Oceanography in San Diego and co-author of the recent study, says the change in sound may have something to do with an increase in the population of the whales. The population has increased in the past several decades with the end of commercial whaling. Hildebrand also notes that only male blue whales make the sounds, so the sound may also be a way for male whales to impress females.

(Audio: KPCC's Alex Cohen spoke with John Hildebrand, an oceanographer at the Scripps Institution of Oceanography).