In romantic terms, the conch is the phonograph of the sea, The representative wants to keep the good.

Scientific explanation is that the inside of the shells is curved shape, inside filling up the air, so when you are in the surrounding environment is very noisy place, the vibration noise makes the air in the shells, as a result, you stick conch into the ear can hear the sound of the tides. When you are in a special quiet room, the sound that came from the surrounding is very few, and the volume is very small, cannot make the air vibration in the shells, so you put the shells on the ear, won't hear the sound of the tides.