Classrooms are full of sound, whether from the outside (street traffic, airplanes, or activity in the corridor or on the playground) or from the inside (ventilation systems, babble and chairs scrapping the floor). During a school day, children are exposed to sound levels that average 72 decibels (dB), fluctuating between 35dB (a quiet library) and 90dB (a noisy restaurant).
Most educational instruction is done aurally: Children must listen to their teachers and remember what is said in order to grasp key concepts and understand instructions and explanations. However, background sounds can cause tremendous communication difficulties.
For speech to be intelligible, a signal-to-noise ratio of 15dB is recommended, which means the teacher’s voice (signal) must be 15dB louder than any irrelevant background sounds (noise). Now, imagine that children are engaged in some individual work and are moving around the classroom. They could generate a sound level of 72dB. To be heard properly, the teacher then would have to speak at a level of 87dB—or to shout continuously.
Unsurprisingly, teachers are particularly at risk of developing voice problems compared with the general population. Anecdotally, some teachers report speaking very loudly when they come home for the evening, until they adjust to the new situation.
For children as well, a bad signal-to-noise ratio can pose difficulties. When speech is masked by background noise, some phonological and/or semantic information can be lost. Children must reconstruct the meaning of a sentence, using their existing knowledge of grammar and the world around them to provide missing or ambiguous information.
“In acoustically difficult surroundings, children may struggle to understand a math problem and have fewer cognitive resources and energy to solve it.”
This process is especially difficult for children with hearing impairment, special educational needs or for whom the language of instruction is not their first language. Noise interference is therefore particularly challenging for inclusive and multicultural environments. In England, for example, 21% of the primary school pupils have English as an additional language.
Overall, the ability to reconstruct degraded phonological input develops until adulthood, and young children, whose classes tend to be the noisiest, might struggle the most. Even if children manage to understand speech within background noise, they must expend cognitive resources to do so—resources that are then unavailable to process, store and act on instructional content. In other words, in acoustically difficult surroundings, children may struggle to understand a math problem and have fewer cognitive resources and energy to solve it.
So what can we do about this? Physical solutions to noise are usually the first to come to mind. Isolating material, absorbent panels, carpets, or changing the tone of the school bell and so on can be a good start to reduce reverberation in the classroom and outside noise.
“The impact of sound levels on learning environments is easily overlooked. With greater attention, some simple adjustments could make big differences in children’s ability to learn.”
However, these solutions can be expensive and may require multiple stakeholders to be involved (e.g. funding institutions, regional boards). Furthermore, they can have side effects. For example, carpets collect dust and thereby reduce air quality. Most importantly, although physical changes in the classroom can reduce sound levels, they do not impact the signal-to-noise ratio because both the background noise and the teacher’s voice are lowered.
How then to optimise the signal-to-noise ratio? Use of microphones to amplify the teacher’s voice may be an obvious answer, but this solution could create an escalade of noise levels that could be particularly stressful.
Another idea is to involve students in monitoring and lowering the internal background noise that they create with their own activities and movements. Interactive tools to visualise noise levels seem promising, although more research is needed on their effectiveness.
The perfect solution has yet to be found. In the meantime, simple concrete solutions can help to reduce stressful noise, such as placing pads (or tennis balls) on chairs’ feet or felt strips on doors that tend to slam.
The impact of sound levels on learning environments is easily overlooked. Yet, with greater attention, some simple adjustments could make big differences in children’s ability to learn.