Many people believe that the noise in the seashells is the roar of the surf and the rustle of the waves. However, it is not clear how the noise of the reservoir can be heard through the sink. There is a logical and scientific explanation for this.
In fact, the shell is a resonator, like any other closed air cavity. Therefore, "sea noise" can be heard not only in the sink, but also in a simple mug, cup, glass, and even in a palm folded in the form of a shell. In any such cavity, external sounds are concentrated. The world around us is not in absolute silence; noises of varying volume are always present. It is these sounds that are reflected by the walls of the shell. The volume and type of "sea song" depends on several factors. If you move the shell away or vice versa closer to the ear, the noise will change. It also depends on the size and shape of the shell itself. This kind of resonator amplifies all sounds inaccessible to the human ear. If the shell is tightly pressed to the head, a person hears not external noises, but blood circulating in the head. When nothing is applied to the ear, a person hears various external sounds. If something prevents the ear from picking up noise, the eardrum begins to perceive internal sounds, i.e. circulating blood, which acts on the ear membrane from the inside. If the human brain was arranged differently, we could hear much more sounds, and the shell would not be our helper in this. Best of all, you can hear the "splash of waves" in large spiral shells. If you hold the shell not close to your ear, but somewhat distant from it, the sound will be louder. The noise will also be more intense if there are many different sounds outside. In any case, the splash that is heard in the shell has nothing to do with the sea. There are many theories related to the nature of these noises, but the most reliable and proven theory is that external sounds are reflected by the shell walls. This theory is easy to verify. If you hold the shell close to your ear in a soundproof room, there will be no noise in the sink. Even despite the fact that blood continues to circulate in the head, and there are air currents in the room.