Putting the Hum in Hummingbird

BirdNote^®

Putting the Hum in Hummingbird

Written by Bob Sundstrom

This is BirdNote.

[Ruby-throated Hummingbird wing hum, 0:04-0:09] 

Just what puts the hum in a hummingbird’s wings? And why don’t other birds' wings hum in flight?

To figure it out, scientists used a specially-built rig to measure air pressure, twelve high-speed cameras, and over 2000 microphones to observe hummingbirds fluttering in place at an artificial flower. This allowed them to make 3D visualizations of the sound of a hummingbird’s wingbeats.

[Ruby-throated Hummingbird wing hum, 0:04-0:09] 

When hummingbirds flap, they create lift both on the downstroke and the upstroke—so twice per wingbeat. The researchers found that the hum derives from the difference in air pressure between the top and bottom of the wings, which alternates forty times a second as the hummingbird flaps. 

The rapidly shifting air pressure produces a harmonic set of sounds, from low to high, creating that iconic, musical hum.

[Ruby-throated Hummingbird wing hum, 0:04-0:09] 

Other birds flap with power on the downstroke only, so there’s no rapidly-changing pressure difference when they fly, making them much quieter. Their wings might whoosh, but only a hummingbird’s hum.

For BirdNote, I’m Ariana Remmel.

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Senior Producer: John Kessler
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Managing Producer: Conor Gearin
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York.
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2022 BirdNote   September 2022    October 2024
Narrator: Ariana Remmel

ID# sound-30-2022-09-15        sound-30

References:
https://www.tue.nl/en/news-and-events/news-overview/15-03-2021-how-humm…
https://elifesciences.org/articles/63107