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Sounds hum-mazing!

I'm Mo with The Discovery Files, from NSF -- the U.S. National Science Foundation.

How exactly does a hummingbird create its distinctive sound? Ever wondered where the hum comes from? Unlike humans who can create noise with their mouths, a hummingbird creates its hum with a flap of its wings.

A team of engineers from Stanford University, Sorama and Eindhoven University of Technology measured for the first time, the precise origin of the sound generated by the hummingbird. Using a unique suite of instruments, including twelve high speed cameras and over two thousand microphones! They discovered, the hum originates from the changes in position and pressure magnitude on the topside and the underside of the wings.

Unlike other birds that generate a whoosh sound once on their downward wing stroke, a hummingbird generates a strong upward aerodynamic force during both the upward and downward wing stroke, generating two strong hum tones per flap.

After digging a little deeper, it turns out, both the downward and upward stroke contribute strongly to the hum, giving the hummingbird its distinct namesake hum.

These new insights could help engineers craft devices to help make drone rotors and everyday appliances like laptop and vacuum cleaner fans quieter.

Discover how the U.S. government's National Science Foundation is advancing research at nsf.gov.

"The discovery files" covers projects funded by the government's National Science Foundation. Federally sponsored research -- brought to you, by you! Learn more at nsf.gov or on our podcast.

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