WASHINGTON (AFP) - Deep in the Amazon, a white-plumed suitor weighing no more than half a pound turns to face his paramour before belting out a deafening, klaxon-like call, reaching decibel levels equal to a pile driver.

Meet the white bellbird, which has just beaten out its rainforest neighbour, the screaming piha, for the title of the world's loudest bird, according to a paper published in the journal Current Biology on Monday (Oct 21).

Biologist Jeff Podos at the University of Massachusetts Amherst and Mario Cohn-Haft of the Instituto Nacional de Pesquisas da Amazonia, Brazil wrote that its calls are so loud, they wondered how white bellbird females listen at close range without damaging their hearing.

The feat is all the more impressive given the species' diminutive size: they're about as big as doves, and the males are distinguished by a fleshy black wattle adorned with white specks that falls from the beak.

Podos said he was lucky enough to witness females join males on their perches as they sang.

"In these cases, we saw that the males sing only their loudest songs," he said.

"Not only that, they swivel dramatically during these songs, so as to blast the song's final note directly at the females."

It's not clear why the females voluntarily expose themselves to the noise at such proximity, which reaches peak levels of 113 decibels - above the human pain threshold and equivalent to a loud rock concert or a turbo-prop plane 200 feet (60m) away achieving liftoff power.

"Maybe they are trying to assess males up close, though at the risk of some damage to their hearing systems," Podos added.

The pair used high-quality sound recorders and high-speed video to slow the action enough to study how the bird uses its anatomy to achieve such high levels of noise.

"We don't know how small animals manage to get so loud. We are truly at the early stages of understanding this biodiversity," he said.