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Why Do Seashells Sound Like the Ocean?

seashell by ocean
Hold this to your ear for the sound of the ocean. (Image credit: MAR007/Shutterstock)

When you hold a seashell up to your ear, you hear the quiet roar of waves crashing on a distant beach, as if sounds from the shell's past environment are still echoing within it.

As lovely as that concept might be, though, it's only a metaphor: When you listen to a shell, you're not really hearing the sound of the ocean. The shape of seashells just happens to make them great amplifiers of ambient noise.

Any air that makes its way into a shell's cavity gets bounced around by its hard, curved inner surfaces. The resonating air produces sound.

The pitch of the sound depends on the size of the shell. Air takes longer to bounce back and forth in a bigger shell than it does in a smaller one, so you'll perceive the pitch of sound emerging from a bigger shell as being lower than that from a smaller one. Whether high or low in pitch, almost all shells sound pleasantly ocean-like.

Original article on Live Science.

Natalie Wolchover was a staff writer for Live Science from 2010 to 2012 and is currently a senior physics writer and editor for Quanta Magazine. She holds a bachelor's degree in physics from Tufts University and has studied physics at the University of California, Berkeley. Along with the staff of Quanta, Wolchover won the 2022 Pulitzer Prize for explanatory writing for her work on the building of the James Webb Space Telescope. Her work has also appeared in the The Best American Science and Nature Writing and The Best Writing on Mathematics, Nature, The New Yorker and Popular Science. She was the 2016 winner of the  Evert Clark/Seth Payne Award, an annual prize for young science journalists, as well as the winner of the 2017 Science Communication Award for the American Institute of Physics.