Call Centers

Because today’s modern call centers are typically laid out in an open plan environment, background noise can be a real issue. Not only is background noise distractive and stressful for employees, noise can transmit through the phone to the customer making communication difficult. The two most obvious solutions are to reduce employee density, and to treat the area as a quiet room, limiting access to essential personnel only, and requiring visitors to limit their conservations and to speak softly.

The next step is to address the acoustics of the center which is a two part process: Isolating the call center from outside noise, and improving the room’s acoustic properties.


If possible, isolating a call center from outside noise interference should be addressed in the planning and construction phase, but the same principles apply when retrofitting an existing space.

Mechanical Equipment Noise
  • Locate mechanical rooftop equipment away from critical listening areas such as call centers.
  • Reduce mechanical vibrations of HVAC equipment, conduit, and ductwork through the use of vibration isolators, vibration pads, and spring isolators.
  • Select air handlers with low sound level ratings.
  • Install acoustic duct silencers in noise critical areas.
  • Specify duct sizes large enough to prevent high air velocities, and select diffusers with Noise Criterion, (NC), ratings of 20 to 25.
  • Use longer duct runs to eliminate crosstalk between rooms and lower mechanical noise.
Interior Noise Transmission

Noise from adjacent rooms can be disruptive in call centers. Over the years the need to reduce construction costs has led to the use of thinner lightweight wall materials which do little to block sound transmission. The sound blocking properties of common walls can be greatly increased by adding mass through the installation of a vinyl noise barrier, and decoupling the partition with resilient isolation clips. This reduces both airborne and structure borne noise transmission. Interior doors leading to hallways and busy areas as well as exterior windows are another noise source. Doors should either be acoustically rated, or at the minimum solid core construction with acoustical door seal kits installed. Exterior windows need to double paned and acoustically rated also.

Unwanted noise can also flank over top of dropped ceiling tiles and into the adjacent space if the common walls are not constructed to the top of the existing ceiling or plenum. If increasing the wall height is not an option, replacing the existing ceiling tile with a barrier ceiling tile, or adding a fire rated barrier material over the existing tile, will greatly reduce noise transmission. During the planning stages, noisy areas such as mechanical rooms, cafeterias, and elevator lobbies, can be isolated from call centers by using buffer zones such as hallways and storage rooms.


The hard surfaces of the walls, floors, and ceilings will cause sound waves to be reflected back and forth producing a reverberant space, which increases sound levels and greatly reduces speech intelligibility. By adding acoustical absorption products such as acoustic wall panels and ceiling absorbers to these hard parallel surfaces, the sound energy is absorbed preventing it from reflecting to the opposite surface. Think of what an empty room in your house sounds likes before and after you add things like carpet, drapery, and furniture which all have absorption properties.

Installing a sound masking system, (sometimes referred to as white noise), is highly recommended to provide a higher level of speech privacy between operators. Sound masking works by producing a unique, digital broadband sound spectrum complimentary to the speech spectrum that effectively covers speech levels. A good sound masking system such as the Lencore Spectre and iNet Systems System fills the ceiling plenum area with a carefully tuned digital sound that filters down into the office space below. Unobtrusively raising the background sound actually masks unwanted office noise, makes surrounding speech unintelligible, creates privacy, and results in call center environments that are acoustically comfortable to work in.