Why do Hummingbirds Hum?

Finally, scientists unlock the secret and take the “hmm?” out of hummingbirds.

Hummingbirds might be instantly recognisable from their eponymous sound, but the cause of the characteristic has long been a mystery. Now researchers say they have cracked the conundrum, finally taking the “hmm?” out of hummingbirds.

David Lentink, the assistant professor of mechanical engineering at Stanford University and a co-author of the research, says that while the hum was known to be linked to the movement of the wings, it was previously unclear what exactly was behind the sound. Pressure changes generated by the flapping, vortices in the air flow, and whistling sounds from the feathers themselves were all among the possibilities.

Now, thanks to 3D sound mapping, it seems the answer predominately lies in the aerodynamic forces, and hence pressure changes, produced as the wings move.

“This alone is enough to really understand what the main source of the hum is,” said Lentink.

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