How to Evaluate a Class Room for Acoustical Renovation

Background noises and reverberations in classrooms distract children, with or without hearing problems. The unwanted noise disrupts the learning process. Each classroom must be evaluated on the following in order to meet ANSI Acoustic standards. These steps are however subject to revision. This is an open project and there is more than one way to renovate a classroom for acoustic improvements based on many factors, like availability of material, installer of the material, cost, classroom dimension etc.


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    To guide the classroom evaluation process, here is a list of background noise sources. Background noise can emanate from: noise traveling through walls from adjacent classrooms, over the ceiling from adjacent classrooms, through doors, around the door frame and under the door, through ventilators or louvers above door units, through HVAC ductwork from adjacent rooms, HVAC noise from ceiling diffusers, through the light fixtures, from outside, through exterior walls and windows, and from the floor above.
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    Ceiling level; the higher the ceiling level the more the room tends to a 'live' acoustic response, which can be detrimental to speech intelligibility and to attention spans in the learning environment. The ceilings (and the floor) are usually the largest single areas in a classroom, and so provide convenient surfaces to accommodate cost-effective areas of acoustic absorbing materials and products. However, if the ceiling is less than 6m high (and even for higher ceilings up to 10m or so), it also provides a useful reflection of the teacher's voice that arrives early enough at the students' ears so as to reinforce the direct sound and enhance speech intelligibility. It is important to be able to control reverberation using acoustic tiles or some kind of sound absorbing material like glass fibre, while also retaining the useful reflective quality of at least the central 50% area of the ceiling. Upgrading strategically located areas of ceiling tiles, combined with additional areas on the walls as required, to acoustically absorbing tiles and finishes will dramatically reduce the reverberation and improve speech intelligibility, and hence attention span.
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    Air handling systems; heaters, air-conditioners, etc. produce a lot of noise especially if ill maintained. Noise can be reduced by lowering the air-flow velocity, installing absorptive fiberglass duct liners or creating noise diffusers or sound traps in the equipment/machinery space. Regular maintenance of the equipment is also helpful.
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    Lighting; lighting can reflect noise if installed improperly. For instance, luminary lights are very bright and reflect as much light as they do noise. This can be improved by installing lights that don't shine directly onto the students. Another thing to note with lighting is that fluorescent lights continuously give off a noticeable buzzing noise which increases reverberation time.
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    Flooring; flooring should have material that improves acoustics. For example, carpeting absorbs air-borne sound, helps block sound transmission to rooms below and reduces surface noise better compared to tile or wood flooring.


  • 1.Another characteristic of ceiling tiles to consider is their articulation class (AC). This measures a tile's ability to absorb speech frequencies that strike the ceiling at angles of 25 degrees, a typical level inside a school classroom. An AC rating up to 200 is recommended.
  • 2.When considering lights, carefully select and place them to minimize noise reflection. Also, keep in mind that dimmers on any type of lighting can actually increase noise levels. Therefore, test these with caution.
  • 3.When choosing carpet, insist on ample padding. Thick carpet with an integrated polyurethane cushion cuts noise levels by absorbing sound and reducing its transmission between floors
  • 4.Speakers should be installed that transmit a steady level of ambiguous noise into the environment. This will drown out distracting noises, such as conversational speech, from being overheard or understood.
  • 5.Equipment such as computer printers should be separated from the students learning area. This will eliminate the line of sight between the machine and the student.
  • 6.Acoustic wall panels can be placed between a reflective surface, such as windows, and the work area in the classroom. If not, noise from the work area can bounce off the window and into the common area.
  • 7.Leaks should be plugged between door and the door jam. Even the smallest openings can allow sound to escape.


  • All of the above, though somewhat costly due to the renovation of the class room which would be required, and are the best known measures according to the set Acoustic standards measures that can be taken in order to provide a better leaning environment for younger children with or without hearing disabilities. The best way to start this approach is by introducing the recommendation (above) as an initial non-costly step while funding for the bigger project of classroom renovation is underway.

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