sea-shells?

[sunnycrest]

why can you hear the "sea" when you hold a shell to you ear?

[Clanad]

Ummm... Another web site says the following:

The common explanation for the "sound of the sea" effect is that the shell amplifies the sound of your blood coursing through your head. Not so, says Verovnik Ivo and Mathelitsch Leopold, in a scientific paper delivered in Udine, Italy. The seashell merely acts as a resonator, amplifying certain frequencies of the noise one finds in any environment.

The New York Times Science Q and A column concurs. When outside noises excite the air inside the shell (which resonates at a characteristic frequency, i.e., "sea-sounding"), those swooshy sounds are created. And there are always outside noises, otherwise known as ambient noises. Close your eyes right now and listen. Hear them?

The fine folks at HowStuffWorks go on to mention that the spiral tips of conch shells were used as early hearing aids. Using the same resonator principle, you can increase your hearing by five to ten decibels by placing your hand behind your ear. 

Who's to know?