Who has not ever tried to listen to the sound of the sea through a shell? It seems like a matter of magic or a white lie to surprise the little ones, but the fact is that when you gently place your ear against the opening of a shell, you can hear an amplified sound of what seems like the soft rumor of the sea.
For decades this unique phenomenon has attracted the attention of children and adults, who in their eagerness to seek an explanation for this fact They often believe that these shells emit the sounds of the place they want to return to: the ocean.
Without wanting to detract from this beautiful metaphor, science has tried to find a more logical and reality-based theory. The first explanation scientists came up with was so plausible that it spread like wildfire. It was thought that the sounds that could be heard through the conch were nothing more than the amplification of the flow of one’s own blood.. She made sense. Not surprisingly, when one rests his head on a pillow he can hear the blood beating through his head. This theory was widely accepted, and among others, it was supported by the famous scientific popularizer Carl Sagan, who ratified in 1973 that the melody that emanated from the shell was nothing more than “the highly amplified sound of our own blood circulating.”
However, it was an easy theory to disprove. If what the conch amplified was the sound of blood, it must have varied or been more intense when performing physical exercise, since sport causes an increase in blood pressure and pulse. However, when they compared the sound that was heard in the shell while the person was at rest and after exercising, they realized that the shell continued to emit the same sound, without any variation.
The scientists insisted that, even so, it must be an internal liquid that was generating such a sound. And what other part of the body has fluids? Precisely the ear. The inner ear is constantly overflowing with endolymph and perilymph fluids.. They are essential liquids that allow us to stay balanced. It could then make sense that, by holding a shell on the outside of this organ, what would be amplified was the noise of the swaying of those liquids.
However, another simple experiment throws this theory off balance as well. The fluid in the inner ear moves every time the head is shaken. That means, therefore, that when moving the angle and direction of our head, so should the sound of the conch. But tilting the head to one side does not produce the expected mini auditory tidal wave. The answer remained a mystery.
The answer is not inside, but outside
Then came the latest theory. What if the answer is not inside the listener but outside? Scientists began to believe that what was heard in the conch was air flowing through the shell, creating a hissing and flowing sound. To confirm this, the researchers they tried to listen to a conch shell in a soundproof room. But, under such circumstances, the conch simply fell completely silent.. “For it to be heard, there must be background noise,” says Andrew King, director of the Center for Integrative Neuroscience at Oxford University and head of the Oxford Auditory Neuroscience Group.
King had found the key. LThe sounds that are heard through the shells and that seem to come from inside them, are not inside it, but from around it. The shell ‘captures’ ambient noise, amplifies it and transforms it into the sounds that end up in our ears. “The conch acts like a resonator, increasing certain sound frequencies, making them louder than they would be without the seashell placed next to the ear,” King details.
The frequency of the sound depends on the shape of the shell, although the sounds they usually pick up are those that are lower in frequency, deeper and more booming. Just like the ones in the ocean.
But seashells are not the only ones capable of evoking a marine environment. Actually, just about any convex surface will do. You can try holding a teacup or bowl to your ears, or using your own cupped hands to achieve the same effect, albeit to a lesser degree. Of course, if you try this experiment in the kitchen, do not expect to find the sound of the sea. Rather, you will hear the hum of the refrigerator or the pipes overflowing with water. You will have to get closer to the sea to really hear the sound of the ocean.
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