Noise Control for Teleconferencing, Distance Classrooms and Webcasting

  • The teleconference room, an important part of the audio circuit, demands adequate acoustical treatment of all room surfaces.

  • The slightest echo can undermine speech intelligibility.

  • Reverberation reduction may require significant sound absorption material.

  • Most offices and conference rooms are too noisy and too reveberant to serve as teleconferencing rooms.

  • The teleconferencing room should be designed as a package with the aid of a professional acoustical consultant, especially when an upscale interior design is required.

Teleconferencing rooms, webcasting rooms and distance classrooms all require the same considerations for noise as traditional broadcasting rooms. Acoustically there are two main areas for consideration. First is noise coming in the room from the outside. Second is to keep the reverberation of the sound inside the room down to a level where the microphone doesn't "hear" reflections causing a hollow or echoic sound that limits speech intelligibility.

Noise Criteria of 20 decibels (NC-20) should exist in the broadcasting room. This means when the room is empty and quiet the sound pressure level in the room is 20 decibels or less. The existing conditions in most cases make achieving this level a challenge. Common noises that create problems are heating & air conditioning systems, telephones ringing or people talking in the next room, office equipment, and traffic noise coming from the street.

Speech Intelligibility in broadcasting requires a Reverberation Time of .75 to 1 second. Reverberation Time (RT60) is the time it takes for noise to reduce in volume by 60 decibels.

Untreated rooms have a variety of reverberation times depending on the size and shape along with the absorptive qualities of the surfaces in the room. Generally, you can expect your room to require additional absorptive materials on the walls, ceilings, floors and/or other reflective surfaces, such as tabletops and file cabinets. Existing reverberation times can be calculated. The amount of absorptive material needed to reduce that time to the recommended RT60 can also be calculated. Once this criteria is established acoustical materials and location can then be specified.

If you are considering installation of a teleconferencing room, webcasting room or distance learning classroom, you should consult with a qualified acoustical designer, as early as possible, to assure your room selection is the optimal location to avoid existing problems. If the location of your room has already been established, your acoustical designer can assist in determining the layout and orientation of monitors, speakers and microphones, as well as other acoustical considerations that will assure the best possible design.

In most applications, Acoustical Treatments are more effective and less expensive when a qualified acoustical designer is consulted early in the process of developing your plan.