Why do seashells sound like the ocean?

It's possible that when you were a child, you were told to hold a shell to your ear so you could listen to the ocean. Why is it possible to hear sounds similar to the sea? Is it possible that we're listening to noises from the past, or is it simpler to explain?

It isn't the sound of the sea according to a professor. It makes sense that people would think it's a sea shell.

If it's not the sound of the sea, what is it?

Andrew King is the director of the University of Oxford's Centre for Integrated Neuroscience and head of the Oxford Auditory Neuroscience Group.

There are a lot of giants in the sea.

Waves bounce around inside the shell due to the hard, curved surfaces inside. King told Live Science that the shell acts as a resonator, boosting certain sound frequencies so that they are louder than they would be without it.

Depending on the shape and size of the seashell, the frequencies you hear will be different. King said that if the seashell has an irregular shape, it will hit multiple frequencies.

Cox likened the seashell to a wind instrument. The air inside the shell will vibrate more strongly. You can amplify the frequencies in the ambient sound by holding the shell to your ears. Your brain pays attention to the sound.

Cox and King say that you don't need a seashell to hear a sound similar to the ocean at home.

Placing your cupped hand next to your ear produces the same effect. The size and shape of the object will determine what you hear.

Background noise must be present for anything to be heard. King said that you wouldn't hear anything in a soundproofed room.

Cox said yes.

Cox said he wouldn't hear anything if he went into the anechoic chamber at the university.

In order to achieve complete silence, an anechoic chamber is a room specifically designed to prevent the reflection of sound from the room boundaries. The CNN report states that these rooms are so quiet that after a short period of time, an inhabitant would be able to hear their heartbeat and their bones creaking, and would eventually lose their balance.

So, it is essential for background noise to be present to hear sounds within seashells, but this does raise a question: Given that the sound you hear when listening to a seashell is simply amplified background noise, when listening to a shell while beside the sea, are you actually hearing the sound of the sea?

"If you use a seashell at a beach, the ambient sound being altered by the shell is the sound of the sea. So, I guess you are listening to the sea indirectly," Cox said.

The original article was published on Live Science in 2011.