RPG Diffusor Systems

Classroom

The primary acoustic goal for a classroom is high speech intelligibility without long-term strain on the teacher’s voice. High speech intelligibility results from a high signal to noise ratio. The signal is the teacher’s voice (or student’s voice). Noise is any extraneous sound produced in the classroom by other students, in adjacent spaces or the exterior. Other contributors to noise include the building’s mechanical, plumbing, conveying, and electrical systems. A high signal to noise ratio can be achieved architecturally by placing sound reflecting and diffusing wall and ceiling surfaces in the front of the room around the teacher and sound absorbing and diffsorbing (mid frequency absorption & high frequency diffusion) surfaces around the student seating area.

Classroom Acoustic Treatment (view from above through ceiling)

Floor

Carpet under students (rear 2/3 of room)
VCT under teacher (front 1/3 of room)

Walls

Front – Reflective (painted CMU/GWB)
Sides – Diffsortive (RPG BAD Panels above 6’)
Rear - Diffsortive (RPG BAD Panels above 6’)

Classroom Acoustic Treatment (view from rear of classroom)

Ceiling

Center / Front 25%
RPG Omniffusors (or RPG Formedffusors) & painted GWB tiles

Walls

Front – Reflective (painted CMU/GWB)
Sides – Diffsortive (RPG BAD Panels above 6’)
Rear - Diffsortive (BAD Panels above 6’)

Ceiling	The ceiling in a classroom is typically a standard 15/16” T-bar suspended system with ACT lay-in tiles. This approach provides too much absorption, especially over the teacher. Instead, 25% of the ceiling area centered over the front part of the room over the teacher should be sound reflective and diffusive. Ideally, this entire area should be RPG Omniffusors or Formedffusors, but a more economical approach is to create a checkerboard pattern of Omniffusors (or Formedffusors) and flat, painted gypsum board (Gyptone) tiles. The remaining 75% of the ceiling along the side walls and in the rear of the room over the students should be high NRC acoustic ceiling tile (ACT) with a Noise Reduction Coefficient of NRC-0.75 or higher.
Walls	The lower walls (below 6’) are often required for book shelves, coat racks, posters, dry marker or chalk boards, artwork display, etc. Acoustic treatment is simply not practical. However, the upper walls (between 6’ above the finish floor and the ceiling) are often available for acoustic treatment. Treat 75% of the upper portion of the side and rear Classroom walls with RPG BAD Panels (2” thick). These panels will provide the required mid-frequency absorption to meet standards on reverberation time while reflecting and diffusing the high frequency sound that is so important for speech intelligibility.
Floor	The floor under the front third of the Classroom should be sound reflective concrete, VCT, wood, etc. The floor under the student desk/seating area should be sound absorptive carpet.
*Warning*	Adding sound absorption alone, such as Acoustic Ceiling Tile and fabric wrapped fiberglass panels will not produce high speech intelligibility. These treatments absorb excessive amounts of sound, especially high frequency sound that is critical for speech intelligibility. Absorption raises and lowers reverberation time and loudness, but does not change the signal to noise ratio. As a result of adding absorption alone, teachers must strain over the course of the day and week to produce enough sound power to keep the students’ attention.

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