There is an opinion that if you put the shell to your ear, you can hear the sound of the sea from which it was brought. However, experts say that the reason for these sounds lies elsewhere.
Perhaps only children really believe that the sounds that can be heard by putting a shell to the ear are the sound of the sea. However, adults often misinterpret the causes of these sounds.
For a long time, one of the main explanations for the "noise of the sea" in the shell was the assumption that the person who applied it to the ear actually hears the amplified sounds that his own blood makes as it flows through the vessels. However, then a simple experiment was carried out, which served as a convincing refutation of this explanation. So, it is known that blood flow in the body increases significantly after intense physical exertion: everyone can experience the validity of this postulate, for example, simply jumping energetically on the spot for a few minutes. At the same time, if, after such exercises, you put the shell to your ear, the “noise of the sea” will not become louder or stronger.
Another explanation, which also had its adherents, was the assertion that the sounds emitted are a consequence of the movement of air masses through the interior spaces of the shell. However, this assumption is easy enough to refute by going into a room with good sound insulation: despite the fact that the air masses in such a room also move, the shell will be silent.
Obviously, the occurrence of such a phenomenon is associated with the action of some other factors. According to experts in the field of physics, the real reason that the shell brought to the ear "emits" sounds similar to the sound of the sea is that the sounds surrounding the listener at this moment, reflecting from the walls of the shell, are distorted and create a characteristic hum. This is due to the fact that the cavity of the shell in this case acts as a resonator, which changes and amplifies the sound of extraneous noise.
By and large, any cavity attached to the ear, for example, a glass or other container, can act as such a "shell". And the different shape that different shells have, determines the fact that their sound will be different. However, each of us, putting a shell brought from a distant journey to our ear, most likely does not think about the causes of this physical phenomenon, but recalls long walks along the sea coast. In this sense, such a shell really is for its owner the source of the sounds of the surf …