If you ever took a trip to the beach as a kid, you may have been encouraged to put a seashell to your ear so you can “hear” the sea. But why can you hear sounds resembling the sea in a shell? Are we somehow hearing sounds from the shell’s past, or is it something easier to explain?
“It’s not the sound of the sea,” Trevor Cox, a professor of acoustics engineering at the University of Salford in the UK, told Live Science in an email. “But since you’re holding a conch to yours Earit makes sense that people would think it could be.”
So if you can’t hear the sound of the sea, what is?
“You hear ambient or background sounds that have been increased in amplitude by the physical properties of the shell,” said Andrew King, director of the University of Oxford’s Center for Integrative Neuroscience and leader of the Oxford Auditory Neuroscience Group.
King explained that the “hard, curved surfaces” inside the shells reflect sound waves, causing the waves to “bounce around” inside the shell. As a result, “the conch acts as a resonator, amplifying certain frequencies of sound so they’re louder than without the conch next to your ear,” King told Live Science in an email.
The frequencies you hear depend on the size and shape of the shell. If the conch has an irregular shape, it’s likely to resonate at multiple frequencies, King said.
“The conch is like a wind instrument,” said Cox. “It has a range of resonant frequencies where the air in the shell vibrates more. Hold the shell to your ear and it’s those frequencies in the surrounding noise that are boosted. Because the sound changes, yours Brain take care.”
According to Cox and King, you don’t actually need a seashell to hear a sound that mimics that of the ocean; You can get a similar experience at home just by using a cup or bowl.
“The same effect is created by placing other objects – or even, to a small extent, your cupped hand – next to your ear,” King said. “In turn, what you will hear is determined by the size and shape of the object.”
However, King noted that “background noise must be present” for anything to be heard. “You won’t hear anything in a completely soundproof room,” King said.
“If I go into Salford University’s anechoic room, which is a completely silent room, I wouldn’t hear anything because there’s no ambient noise,” Cox said.
An anechoic room is a room specifically designed to achieve total silence by preventing “the reflection of sound from the room boundaries”. the University of Southampton (opens in new tab). these rooms, according to a 2018 CNN report (opens in new tab)are so quiet that a resident could hear them after a short time Heartbeat and also their bones creaked or creaked and would eventually lose their balance “because the absolute lack of reverberation sabotages your spatial awareness”.
So it’s important for background noise to be present in order to hear sounds in shells, but this raises a question: given that the noise you hear when listening to a shell is simply amplified background noise when you listening to a shell by the sea, do you actually hear the sound of the sea?
“If you use a shell on a beach, the ambient sound that is altered by the shell is the sound of the sea. So I’m guessing you’re hearing the sea indirectly,” Cox said.
Originally published on Live Science on February 16, 2011 and rewritten on July 22, 2022.
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