London, Nov.7 : Thousands of hours of humpback whale sounds have been recorded off the coast of Queensland and analysed to reveal a secret and ancient language of the deep sea.

Over three years, researchers have identified at least 34 recurring sounds - some lasting less than a second and others stretching for more than 10 - that can be linked to specific, different social settings.

"I've found that they have this massive repertoire. I think their communication system is a lot more complicated than we gave them credit for," the Daily Mail quoted University of Queensland researcher Dr Rebecca Dunlop, as saying.

From high-pitched squeaks, shrieks and cries to purrs, groans and low yaps, Dr. Dunlop mapped the repeated sounds for a paper published this month in the Journal of the Acoustical Society of America.

Some noises represent aggression and competition, others affection and concern.

The "wop", for example, is common in mother and calf pods. "It's one of the most common that you'll hear," she said. "It's probably a mum-calf contact call."

Other, higher-frequency signals are used when males are competing for the affections of a female.

"These high-frequency cries and screams (are also heard) when they're having a bit of a row," she said.

Dr Dunlop describes the male "purring" sound as a "C'mon baby" call to females, used as a mating signal.

"The lower the sound, the bigger you are," she said.

The sounds were recorded using an antenna attached to a buoy about a kilometre offshore.

Dr Dunlop's paper, co-authored with the UQ's Michael Noad, catalogues the vocalisations of migrating east Australian humpback whales using 660 sounds recorded from 61 groups of the ocean giants. (ANI)