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Putting the Hum in Hummingbird
Uncovering physics of that iconic, musical hum.
© Mark Moschell
To figure out the source of a hummingbird’s hum, scientists built a special rig to measure air pressure, twelve high-speed cameras, and over 2,000 microphones to observe hummingbirds fluttering in place at an artificial flower. 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.
BirdNote is supported by The Cornell Lab of Ornithology, dedicated to conserving Earth’s biodiversity through education and science.
BirdNote®
Putting the Hum in Hummingbird
Written by Bob Sundstrom
This is BirdNote.
[Ruby-throated Hummingbird wing hum]
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]
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]
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.
BirdNote is supported by The Cornell Lab of Ornithology, dedicated to conserving Earth’s biodiversity through education and science. More at allaboutbirds.org.
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Senior Producer: Mark Bramhill
Producer: Sam Johnson
Managing Producer: Jazzi Johnson
Managing Producer: Ariana Remmel
Content Director: Jonese Franklin
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 & November 2026
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-hummingbirds-hum
https://elifesciences.org/articles/63107
Bob Sundstrom
Writer
Ariana Remmel
NarratorSights & Sounds
