CONTROLLING NOISE IN CLASSROOMS

Poor acoustics is a problem in classroom environments around the country. A student’s ability to learn is greatly reduced in a noisy classroom. Reverberation and background noise can make it difficult to hear and understand the instructor, reducing concentration and attention span. The problem is even more serious for students with hearing problems, learning disabilities, or language barriers.

The United States is going through its largest phase of school construction and renovation in history. Although the need for good classroom acoustics has been known for decades, until fairly recently this information was not made readily available to architects and school planners.

In addition to room reverberation, HVAC system noise can be an issue, especially in buildings with older HVAC systems. When designing an HVAC system in new schools there are some basic guidelines that will eliminate most mechanical noise issues:

• Locate mechanical rooftop equipment away from critical listening areas such as classrooms.
• 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.