Good vibrations: underwater sound systems and speakers are creating a pulse in residential pool construction. Here's what you need to know about this emerging trend

Pool & Spa News, Feb 27, 2004 by Shabnam Mogharabi

Still, Phillips remains ambivalent about the promise of underwater sound. In fact, a client whom he felt sure would want an underwater sound system decided not to opt for the feature, even though she was a former Olympic silver medalist in synchronized swimming.

"Most of our clients are looking for visual elements," Phillips says. "Clients want their pools to be structurally sound, hydraulically superior and visually appealing, but they're not utilitarian users. It depends on the client."

Tips of the trade

It's important to ask the right questions about underwater sound systems. Most manufacturers recommend keeping the following tips in mind when researching and installing underwater speakers:

* Determine how many and which type of speaker--whether moving coil or piezoelectric--best fulfills the needs of the client.

* Talk to the manufacturer about how many speakers he or she recommends installing. Residential pools typically need one or two speakers at most.

* Ask for a frequency response plot and sound pressure level (SPL) plot. Keep in mind, a wide-level response is needed for pleasant sound, and frequencies below 200 Hz can cause swimmer disorientation.

* Speaker placement should be at a depth of approximately 6 feet for proper acoustical performance.

* Use corrosion-resistant metal, such as brass or stainless steel, to construct the speaker's forming shell.

* Hire a licensed electrician to install and wire the system, following the bonding and grounding rules in NEC Article 680.

* Amplifiers must be UL-listed and attached by power cord to a circuit breaker, aka GFCI. Keep in mind, a dedicated isolation transformer is necessary for each piezoelectric speaker installed.

* Use a calibrated hydrophone, which is basically an underwater microphone, to measure sound quality and quantity, if necessary.--S.M.