Noise negatively affects the cognitive development of children

It is not without reason that noise can sometimes be called “noise pollution”. Too much noise can disrupt concentration and even, according to a recent study, affect the results of cognitive tests carried out in children.

A study that lasted two school years

Scientists from the ISGlobal research institute in Barcelona recorded the noise level in 38 schools in Barcelona with sound level meters, in decibels (dB). The recordings were made in the school street, the school yard and inside the classrooms.

These measurements were made two school days a week for a period of 12 months, which encompasses two school years. In parallel with these recordings, the researchers subjected the 2,680 schoolchildren aged 7 to 10 from these establishments to cognitive tests. The objective was to measure performance on attention and working memory.

Noise that disrupts cognitive abilities

The results of this work, published in the journal Plos Medicine, show that cognitive development was slower among students in schools most exposed to traffic noise. For example, in schools where the outside noise level was 5 dB above average:

• Students’ working memory was 11.4% slower than average;
• The same effect was observed for attention span: with 4% above-average inattention;
• For so-called complex working memory tests, in which schoolchildren have to process more information, there was a 23.5% drop from the average.

The most harmful noise peaks

The researchers also compared the levels of noise pollution in schools with those at home and in this case, they did not find a link with the cognitive development of the child. “This could be because noise exposure at school is more harmful as it affects the most important periods for concentration and learning processes.” according to Maria Foraster, lead author of the study.

On the other hand, noise peaks, such as a horn for example, could be even more negative than continuous loud noises. “This finding suggests that noise peaks inside the classroom may be more disruptive to neurodevelopment than the average number of decibels.“, she explains.

First study of its kind

Dr Maria Foraster recalls that this is “the first study to assess the impact of noise on children’s cognition, measured both in the classroom and outside of school“. The average sound levels recorded were 63.6 dB in the school street, 53.5 dB in the courtyard and 38.6 dB in the classrooms. As a reminder, the WHO recommends that the levels traffic noise”must not exceed 53 dB in a day“.