Whether you've tuned it out or it drives you nuts, it surrounds you constantly-the noise, noise, NOISE! Especially in the age of cubicle farms and low-wall offices, we're bombarded by noise-the loud talker at the next desk, the roar of the air conditioning or heating systems, the clattering of keyboards, the chatter of our co-workers working the phones. It can drive you to distraction.
The acoustics of an office are often overlooked when a space is designed. However, acoustical design is a valuable way to study how sound moves through a space and to create an office environment with fewer distractions that allows employees to be more productive. Creating a quiet office requires an integrated design approach with a design professional or acoustical engineer working with the client to create a space that is both optimal for concentration, and visually attractive. That relationship should be established early in the schematic design phase to identify acoustical problems.
Among the acoustical problems a business may want to address are: many phone calls happening at once; reverberation (echoes and sound reflection) in large rooms; conversational privacy; foot traffic; mechanical and electrical equipment; and exterior ambient sound.
There are numerous ways to mitigate ambient sound (see sidebar for more), including incorporating materials with appropriate STC (sound transfer coefficient, for reflecting sound) ratings and NRC (noise reduction coefficients, for absorbing sound) ratings, and separation between spaces. With planning, businesses can help make spaces quieter and employees more productive.
Reducing Noise From Within
Walls: Design walls with a sound transfer coefficient rating of 50 or more within offices and smaller conference rooms where conversations are generally more confidential (higher ratings indicate higher wall density). Less sound is transmitted through a denser material with more sound reflected back into the room, thus keeping conversations private.
Wall Material: The best solution is building two walls separated by an air space or filled with fiberglass batt insulation. If cost is an issue, simply stagger the framing studs and fill the cavity with batt insulation. Partitions work best when installed in uninterrupted sections from the floor to the underside of the ceiling. All joints in the wallboard should be taped and air gaps sealed.
Reducing Reverberation: Reverberation can be a major issue in larger conference rooms and caf spaces. Use fabric wall panels and soft furniture to absorb sound.
Ceilings and Floors: The ideal ceiling and floor material will have a noise reduction coefficient of .75 or better. Most acoustical ceiling tiles are effective against reverberation. The fraction of sound not reflected or absorbed into the tile will transmit through the tile and into the ceiling cavity. For this reason, a ceiling made of acoustical ceiling tiles should not be used alone to ensure conversational privacy.
HVAC: HVAC (heating, ventilation and air conditioning) ductwork can carry sound from one room to another. Run main branch ductwork outside of private offices and meeting rooms, avoid putting them through wall penetrations connecting multiple rooms, and duct all return air. Sound dampers can be installed in ductwork to reduce sound transmission when ductwork goes between walls.
Carpeting: A carpet's main advantage is reducing noise from foot traffic and reducing sound transmission to and from the floor below. Thicker carpets are more efficient at sound absorption but may wear faster compared to thinner, more durable blends with potentially lower life cycle costs.
Doors: Choose pivoting doors instead of sliding doors where you desire less sound transmission, as pivoting doors sit on their frames more firmly and seal better against sound.
Glass Wall Systems: Glass walls are terrible insulators of sound, but where they are aesthetically desired, put a frame between the glass system and the carpet (not onto the concrete beneath) to provide a better sound barrier.
Cubicle Dividers: Fabric panels further reduce sound transmission between employee workstations. Some companies choose to keep their dividing partitions lower than the recommended 60-inch height to encourage team building, but this decision should be based on specific work needs. For example, a call center may want higher cubical partitions for noise reduction.
Location, Location, Location: Locate mechanical rooms, copy rooms and restrooms away from private offices and conference rooms to significantly lessen unwanted sounds.
White Noise: Instead of blocking noise, white noise technology installed in ceilings evenly distributes low frequency sound-white noise-throughout an area, similar to the sound of air movement. The occupants can adjust the level of white noise.
Reducing Outside Noise
Avoid locating a business close to congested areas near airports, highways, railways and factories that generate high ambient sound levels that make their way into a building through windows and doors, typically the weakest rated material for noise reduction.
Create a sound barrier between the windows on a ground floor office and the open office space to limit sound from coming from outside. For example, in a lobby, you may want a low partition behind the reception desk to limit outside sounds coming into the main office area.
Research planned development of the surrounding area to limit the possibility of future infrastructure disrupting employee comfort. Consider a wooded office park zoned for business development only.
Consider the use of sound barriers, such as an earth berm, located close to the building or close to the source of the sound. Avoid locating a sound barrier midway between the source and the receivers.
Avoid operable windows. Most commercial HVAC systems operate best with fixed windows to maintain adequate climate control throughout the year.
Install interior drapery to block sound.
Design exterior walls with a high sound transfer coefficient (STC), such as brick or concrete, and face them toward the sound's source. (A higher STC-rated wall reflects more sound away from the building.)
Jason Bailey is a project manager at TMS Architects in Portsmouth and also teaches Introduction to Architecture at the University of NH as an adjunct instructor. He can be reached at 603-436-4274 or JasonB@tms-architects.com.
Current Issue - May 2024