- The Washington Times - Tuesday, May 10, 2005

A child banging on the drums, a washing machine rattling and rumbling, and the big-screen television blaring the latest blockbuster are sounds that in the typical household become unwanted noise.

“Instead of isolating the loud room, we are isolating the quiet rooms and trying to soundproof those rooms,” says Catherine Armour, chairwoman of design at Corcoran College of Art and Design, part of the Corcoran Gallery of Art in Northwest.

Soundproofing, controlling the level of noise entering and escaping a room, can be achieved by adding a second layer of drywall; using specialized products for the floor, walls and ceiling; or using fabric instead of wood in room design, as suggested by metro-area interior designers. At the same time, using quiet appliances helps prevent the creation of excess noise, they say.

Sound is a wave in the air that displaces air molecules and travels as the air is compressed and expanded, says Eugenie Mielczarek, emeritus professor of physics at George Mason University in Fairfax.

“If there was no air, we wouldn’t hear sound,” says Ms. Mielczarek, who holds a doctorate in physics.

The most effective soundproofing method is using curtains, especially if the material is mounted with a ripple to reflect the sound in different directions, says William Parke, professor of physics and acting chairman of the department of physics at George Washington University in Northwest.

“Curtains have fibers that respond to the sound by vibrating and take energy away from the sound by vibrating,” says Mr. Parke, who holds a doctorate in physics.

Soft surfaces, such as curtains, upholstered furniture, rugs and carpeting, tend to absorb sound. Wood and other hard surfaces, which consist of tightly bound molecules, reflect the sound’s energy, Mr. Parke says.

Using surfaces with textures is another way to absorb sound and reduce sound transmission. Acoustical tiles, for example, have small holes for that purpose.

“The sound goes in the hole, scatters in the hole, and loses energy every time it reflects and scatters,” Mr. Parke says.

Interior designer Skip Sroka recommends installing two layers of drywall instead of one on the ceiling, walls and floor to reduce sound.

One layer of drywall or insulation is not thick enough to stop sound travel, he says.

Sound can travel from one floor to another and from one room to the next through the drywall and any openings, such as vents and utility outlets and boxes.

“If you want sound insulation, don’t use recessed lighting because it transmits the sound from cutting a hole in the ceiling,” says Mr. Sroka, owner of Sroka Design Inc. in Bethesda.

Mr. Sroka suggests using neoprene, a synthetic rubber, around wall sconces and any lighting fixtures to prevent sound travel, particularly in a theater room, where loud volume can cause vibrations. The neoprene is placed where glass comes in contact with metal to stop the glass from vibrating, he says.

For walls, Mr. Sroka recommends using sound-absorbing panels or panels made of homosote, a type of porous board, and wrapped in fabric. The walls can be angled so they aren’t exactly parallel, improving acoustics and helping keep sound from bouncing back and forth, he says.

Mounting wall brackets at different angles with surfaces that are covered with a soft inelastic material, which helps absorb sound, provides the same effect, Mr. Parke says. The sound will reflect off the different surfaces instead of bouncing back and forth and forming a standing wave, he says.

Floors can be soundproofed with a layer of cork, a textured and dense material, underneath carpet padding or another floor material, Mr. Sroka says.

Acoustic floor mats also can be used to soundproof for footfall noise, says Portia Ash, business manager for residential noise control at Owens Corning, a manufacturer of building materials based in Toledo, Ohio. The floor is floated off the joist with plywood or cement, and the floor mat and finished floor are laid on top, she says.

“The purpose is to isolate sound and to break up vibrations and to keep footfall noise transfers from one floor to the next,” Ms. Ash says.

In addition, caulking the corners of a room, the area located between the drywall and floor, and any other openings before carpeting is laid helps seal a room and prevent sound from escaping, says LeRoy Froom, professor of radio production at Montgomery College in Rockville.

“If you have any exposed walls [or] flat portions of a wall, that’s where the sound is going to bounce around,” Mr. Froom says.

The use of quiet appliances, such as dishwashers, washers and dryers, is another way to control sound levels.

“As laundry moves out of the basement and becomes part of the main household, that noise level is extremely important to consumers to not interrupt their daily lives,” says Casey Tubman, product development manager for Kenmore laundry appliances.

Sound-absorption material is placed around the sides and the top of Kenmore laundry appliances along with sound-deadening materials on the steel parts to change the sound’s acoustical nature, Mr. Tubman says.

Tuned absorbers also are used in Kenmore washers, as with Maytag’s units. The tuned absorbers are pieces of metal that vibrate to help cancel out sound and vibration during the spin cycle.

The motor in the Maytag Neptune front-load washer uses magnets instead of belts and brushes to move the tub, says Brett Oleson, manager of sales training at Maytag Appliances.

“By eliminating those two pieces, you’ve eliminated a lot of noise coming from the washing and spinning cycles,” Mr. Oleson says.

Six sound-dampening strips in the Maytag Neptune dryer help absorb sound caused by buttons or metal pieces on clothing clinking against each other or the dryer, Mr. Oleson says. The strips are made of asphalt, with a bumpy surface, he says.

Asphalt is also used inside the door of Maytag’s Jetclean II Dishwasher. A layer of polypropylene insulation is placed on the tops and sides of the unit and sandwiched between the outer door and inside liner to help absorb sound, Mr. Oleson says.

“When homes are not treated for noise, every member of the family isn’t able to fully enjoy activities in the home,” Ms. Ash says. “Someone is sacrificing while someone else is doing the activity.”

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