Let’s consider the normal classroom. We have a room that is approximately 24 feet by 38 feet or 912 square feet, (84.73 square meters). This room is a rectangle that has flat walls, a flat ceiling. The walls, doors, windows and ceiling are not soundproof so outside sounds can filter through the walls and windows. There are no sound baffles on the walls to absorb and disburse noise so every sound in this room reverberates from one wall to another until it loses momentum and disperses.
Now let’s add a little outside noise to this classroom. A lawn mower outside. A truck driving by. A car horn honking. All of these sounds enter the classroom from the outside facing wall and windows and then reverberate around the room. Now let’s add an interactive whiteboard, an overhead projector, a ventilation system and a few computers to the room. Now the noise level has increased a bit more. Now let’s put about 20 desks, 20 chairs, a teacher’s desk and chair and a couple of tables in this room. Then bring in 20 students and a teacher. All breathing, talking, whispering, shuffling their feet, walking, moving chairs, desks, papers, pens and pencils. Then let’s throw in some noise in the hallway outside the classroom; footsteps, talking, yelling, laughing, rolling carts, etc. Well you get the idea. A very loud environment.
Signal to Noise Ratio for Classrooms and Hearing
typical classroom noise levels range from 41 to 51 dB, (Bess, Sinclair, & Riggs, 1984; Crandell & Smaldino, 1994), there is obviously a problem that needs to be addressed. Consider also that this research is old and before the proliferation of overhead projectors and personal computers in schools. To achieve a suitable SNR for children, teachers need to speak approximately 15 (dB) louder than the background noise in the classroom according to recommendations from the American Speech-Language-Hearing Association, (ASHA, 1995).
What to do
One option is to soundproof the classroom. At the current time it would cost approximately $4000 – $6000 per classroom to do this. For most school districts this is not possible. Another option is to get students in the classroom and everyone walking by in the hallways to be really, really quiet all day. Also, not very practical. The third option is to provide professional quality voice and sound reinforcement systems in every classroom or to provide high quality portable systems. This would cost approximately $800 – $2,500 per classroom to accomplish depending upon the systems purchased and the costs for installation.
Obviously the only practical solution to this serious problem is that school systems install voice and sound reinforcement systems in every classroom. Yes, the cost for this for a large school system is still significant but consider the cost for communities and the country for every student who does not get a proper education because he or she could not hear what the teacher was saying in most of their classes. If 20 parents were asked if it was worth $50 for their child to hear properly in class and to improve their comprehension and test scores by 10% -20%, (McCarty, CEFPI Paper Presentation, 2003, and BYU Department of Human Development study, 2003, Bernier, Odyssey Middle School, Orange County Public Schools, Florida, 2003), would they invest the $50? Of course they would.
Voice and sound reinforcement systems are already becoming a standard in US and Canadian schools. These classrooms are called ‘enhanced classrooms’. US federal law mandates that any classroom that has at least one hard of hearing student must have a voice and sound reinforcement system of some kind installed.
If your school does not install voice and sound reinforcement systems in all their classrooms, speak with them about this. Pass along some of the research from this blog and the resources we provide. This issue is too important to millions of students all over the world and the societies they live in.