Due to the reflective quality of walls and floors, indoor waterfeatures may present loudness problems. Make sure you err on the quiet side and be careful designing in smaller spaces — especially if the water will fall near offices or other fixed areas where people must work or talk.
“Whatever you think will be adequate is probably still going to be too loud,” says Tom Mallonee, president of CMS Collaborative, based in Santa Cruz, Calif.
Some waterfeatures are innately quiet. For example, low-flow varieties are generally a shoo-in. Smooth water walls, with the fluid oozing down the face, can be built as high as 25 feet and still run almost silent, Mallonee says. A little flow reduction also goes a long way audibly. “Say you turn it down from 35 gallons per minute to 28,” he says. “It won’t change the appearance much, but it will quiet the sound by one-third or even half.”
Laminar sheets up to approximately 3 feet can be crafted to cut cleanly into the catch pool, making a quiet entry. “It’s more of a hissing sound with a little bit of low-frequency thrown in,” Mallonee says. Try not to spill more than 20 gallons per minute per foot. This should work indoors, where you don’t have to worry about winds breaking up the sheet.
Spouts lend a similar tone, but hold together longer than continuous sheets. That’s why on some projects, Mallonee will break a long weir wall into several uniform notches that create 3- to 12-inch-wide spouts.
When working inside, try to avoid waterfeatures that make slapping sounds. “I don’t find uneven slapping to be pleasant in an interior space,” Mallonee says. “I prefer a more constant, continuous sound.” Rain curtains, for instance, fit the bill.
If you find that the waterfeature is too loud after construction, try adding absorptive materials to the space. Acoustic experts sometimes use “banners,” which are fiberglass cores wrapped in vinyl, to sop up sound, explains Lily Wang, a professor of architectural engineering at the University of Nebraska-Lincoln, and chairwoman of the Acoustical Society of America’s Technical Committee.
Special wall panels and ceiling tiles also absorb sound. Even carpet and bunched-up drapes can do the trick — the thicker, the better, Wang says.