Some crucial factors to consider that enhance and improve the acoustic environment of classrooms include:
Controlling external noise
Classrooms situated away from busy areas of a school – such as the playground and reception areas – will be less impacted by external noise. In some cases, external noise interference can be controlled by using areas such as corridors, toilets and storage rooms as buffer zones.
Ideally, schools should be sited away from busy roads. However, if the school is located on or near a busy road, traffic noise can be mitigated by placing classrooms as far away from the road as possible on the school site, facing them away from the road, and introducing slopes and embankments covered with plants as buffers. The challenge then becomes controlling noise without sacrificing too much daylight, ventilation and a view of the outside.
A favoured solution to this challenge is the use of automatically controlled skylights, which open during breaks, thereby ensuring proper ventilation and temperature control without letting in traffic noise during class.
Windows with a pane construction of 2 layers with different glass thickness (e.g. 4mm and 6 mm) will achieve a better sound insulation than a window with a standard glazing unit. Panes with 3-layer glass units with different distances between glass, and glass thickness, also perform better than the standard solution. Using a different gas filling will also have an effect – krypton gives better sound insulation. And finally, laminations are another way to achieve higher sound insulation of the glazing unit.
Internal noise
In principle, sound generated inside a building can be separated into two sources of transmission – airborne sound and sound transmitted through the building itself. Airborne sound, from human activities in adjacent classrooms or from mechanical noise, travels through air, walls, floors and ceilings. Inside the classroom, unwanted noise can be reduced by using a false ceiling with acoustic tiles, tables and chairs with rubber feet, and the addition of acoustic panels if necessary. Porous materials can also be used to absorb sound, while curtains can improve the acoustics by dampening echoes and reverberation.
Room shape
Seating arrangements within the classroom should ensure that teachers can be readily heard by students, so the closer they are, the better. A rectangular room with a higher length to width ratio most easily allows for this type of seating set-up.
This is not to say that room shape alone can replace proper acoustics. As we discuss in chapters 5 and 6 of the e-book "Building Better Schools: 6 ways to help our children learn", flexibility is one of several factors which are very important to classroom design.
A good acoustic environment in classrooms allows teachers to be heard clearly and reduces distraction from external noise. It also allows students to work effectively together in groups when required, while permitting the concentration necessary for solo project work, or when sitting exams.
Sources
- DEIC Basic Book: Acoustics: Noise or sound
- Crandell and Smaldino: Classroom Acoustics for Children With Normal Hearing and With Hearing Impairment, 2000
- Picard and Bradley: Revisiting speech interference in classrooms. 2001
- Clever Classrooms, Summary report of the HEAD project, University of Salford, Manchester (2015)