The Secrets of Synchronized Swimming

Speaker of the Pool

What do synchronized swimmers and potential terrorists have in common? It’s not the glitter. To synchronize reverse scoops and barrels beneath the water, swimmers rely on some rather impressive speaker technology. But, when not providing Olympic audio inspiration, that same equipment serves as a first line of defense against potential underwater terrorists.

O. E. Enterprise/Oceanears has provided speaker technology to every level of synchronized swimming. From the 1996 Olympics in Atlanta to the current US national team, its piezoelectric speakers have kept swimmers from every country in the world in rhythm. But, when company owner Ed Harper isn’t posing for photos with attractive blondes, he’s speaking with the military about how to notify swimmers that they’ve entered restricted space and, if necessary, stop them dead in the water.

Try talking to someone below the water and you’ll understand the difficulty of underwater sound. The impedance of water is 3,600 times that of air. What little sound is transmitted beneath the water relies more on bone conduction through the middle and inner ear than the traditional route through the eardrum. There’s a 62-decibel offset between sound in the air and that in water. Normal talking is approximately 60 db, meaning communicating at that same relative intensity requires 122 db in the pool. Doesn’t sound that bad till you realize 120 db is somewhere between the noise level created by a jet airliner and that of the threshold for human pain.

But swimmers can’t perform flamingos and cranes in unison if the music is only audible above the water. So, Oceanears technology provides a method for getting the sound out without breaking the bank. Most air based audio speakers rely on a moving coil design that requires a large displacement of air molecules to create noise. According to Harper, moving water that long distance causes problems. Instead, Oceanears speakers rely on piezoelectric technology similar to smaller, above-water tweeters. Voltage applied to ceramic causes much smaller vibrations that are nearly invisible to the naked eye. With water molecules much more tightly packed than those in air, the small displacements can put out much bigger sounds under the water than on ground.