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How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight

How hummingbirds hum is not fully understood, but its biophysical origin is encoded in the acoustic nearfield. Hence, we studied six freely hovering Anna’s hummingbirds, performing acoustic nearfield holography using a 2176 microphone array in vivo, while also directly measuring the 3D aerodynamic f...

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Autores principales: Hightower, Ben J, Wijnings, Patrick WA, Scholte, Rick, Ingersoll, Rivers, Chin, Diana D, Nguyen, Jade, Shorr, Daniel, Lentink, David
Formato: Online Artículo Texto
Lenguaje:English
Publicado: eLife Sciences Publications, Ltd 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8055270/
https://www.ncbi.nlm.nih.gov/pubmed/33724182
http://dx.doi.org/10.7554/eLife.63107
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author Hightower, Ben J
Wijnings, Patrick WA
Scholte, Rick
Ingersoll, Rivers
Chin, Diana D
Nguyen, Jade
Shorr, Daniel
Lentink, David
author_facet Hightower, Ben J
Wijnings, Patrick WA
Scholte, Rick
Ingersoll, Rivers
Chin, Diana D
Nguyen, Jade
Shorr, Daniel
Lentink, David
author_sort Hightower, Ben J
collection PubMed
description How hummingbirds hum is not fully understood, but its biophysical origin is encoded in the acoustic nearfield. Hence, we studied six freely hovering Anna’s hummingbirds, performing acoustic nearfield holography using a 2176 microphone array in vivo, while also directly measuring the 3D aerodynamic forces using a new aerodynamic force platform. We corroborate the acoustic measurements by developing an idealized acoustic model that integrates the aerodynamic forces with wing kinematics, which shows how the timbre of the hummingbird’s hum arises from the oscillating lift and drag forces on each wing. Comparing birds and insects, we find that the characteristic humming timbre and radiated power of their flapping wings originates from the higher harmonics in the aerodynamic forces that support their bodyweight. Our model analysis across insects and birds shows that allometric deviation makes larger birds quieter and elongated flies louder, while also clarifying complex bioacoustic behavior.
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spelling pubmed-80552702021-04-22 How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight Hightower, Ben J Wijnings, Patrick WA Scholte, Rick Ingersoll, Rivers Chin, Diana D Nguyen, Jade Shorr, Daniel Lentink, David eLife Evolutionary Biology How hummingbirds hum is not fully understood, but its biophysical origin is encoded in the acoustic nearfield. Hence, we studied six freely hovering Anna’s hummingbirds, performing acoustic nearfield holography using a 2176 microphone array in vivo, while also directly measuring the 3D aerodynamic forces using a new aerodynamic force platform. We corroborate the acoustic measurements by developing an idealized acoustic model that integrates the aerodynamic forces with wing kinematics, which shows how the timbre of the hummingbird’s hum arises from the oscillating lift and drag forces on each wing. Comparing birds and insects, we find that the characteristic humming timbre and radiated power of their flapping wings originates from the higher harmonics in the aerodynamic forces that support their bodyweight. Our model analysis across insects and birds shows that allometric deviation makes larger birds quieter and elongated flies louder, while also clarifying complex bioacoustic behavior. eLife Sciences Publications, Ltd 2021-03-16 /pmc/articles/PMC8055270/ /pubmed/33724182 http://dx.doi.org/10.7554/eLife.63107 Text en © 2021, Hightower et al https://creativecommons.org/licenses/by/4.0/This article is distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use and redistribution provided that the original author and source are credited.
spellingShingle Evolutionary Biology
Hightower, Ben J
Wijnings, Patrick WA
Scholte, Rick
Ingersoll, Rivers
Chin, Diana D
Nguyen, Jade
Shorr, Daniel
Lentink, David
How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight
title How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight
title_full How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight
title_fullStr How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight
title_full_unstemmed How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight
title_short How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight
title_sort how oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight
topic Evolutionary Biology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8055270/
https://www.ncbi.nlm.nih.gov/pubmed/33724182
http://dx.doi.org/10.7554/eLife.63107
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