Roberts Jane Wood, age 10, of Tucson, Arms., for her question:

Why do you hear the sea in a seashell?

The truth is you do not hear the sea in a seashell. But do not let this spoil the fun for you. Put the mouth of a largo shell to your ear and listen for the soft whispering Swop‑nosh, Swop‑nosh. Let it remind you of the whispering waves on your favorite beach.

Actually this is a trick with acoustics ‑the science of sounds. Your outer ear is a sound chamber, designed to gather and concentrate sound waves. The seashell is an echo chamber. It can bounce sounds from wall to wall and echo them to and fro.

The seashell echo chamber mothers a sound from your ear. Of all things, it gathers and magnifies the sound of your pulse. Your ear gets this sound back from the shell. So, what you hear in a seashell is not the distant surf. It is the soft sound of your own bland pulsing through your own body.